CA2114938A1

CA2114938A1 - Temperature control apparatus and a central unit for temperature control apparatus

Info

Publication number: CA2114938A1
Application number: CA002114938A
Authority: CA
Inventors: James G. Tangney
Original assignee: James G. Tangney; Cassowary Limited
Current assignee: CASSOWARY Ltd
Priority date: 1991-08-06
Filing date: 1992-08-05
Publication date: 1993-02-18
Also published as: ATE136356T1; WO1993003311A1; DE69209652D1; EP0599889B1; AU2401892A; EP0599889A1

Abstract

2114938 9303311 PCTABS00019 Temperature control apparatus (1) for controlling temperature in a building comprises a central unit (2) for supplying a heat transfer medium, namely, water to a remote unit (3) through a circulating circuit (4). The central unit comprises a reversible refrigeration circuit (8) comprising a main heat exchanger (11) which exchanges heat between the refrigerant medium and the heat transfer medium. A return temperature sensor (32) monitors the return temperature of the heat transfer medium to the main heat exchanger (11), and a differentiating circuit (34) determines the rate of exchange of change of the return temperature with respect to time.
A microprocessor (26) controls a compressor (12) of the refrigeration circuit (8) for varying the energy output of the refrigeration circuit (8) in response to the rate of change of the return air temperature.

Description

wo 93/03311 pcr/lEg2/oooo4 3 3 ~

'ITemperature control appara$us and a central unit for temperature control apparatus"

Field of the invention The present invent;on relates to mult;-~one temp~ture control 5 apparatus, and in particular, though not lim;ted to multi-zone space temperature control apparatus for cooling and/or heating respective zones of a bu;lding or the like independently of each other. The invention also relates to a central un;t for supplying B heat transfer medium to at least one remote unit of 10 temperature control apparatus. Further, the invention relates to a remote unit for rece;ving a heat t~ansfer medium from a central unit for controllin~ temperature. The invention also relates to ~emperatur* control apparatus which comprises at least one central unit and one remote unit. The inYention also relat~s to a method for controlling the energy output of the central unit.

~b~
Temperature control apparatus for space heating andlor cooling for controlling the temperature in one or more ~ones of a building is known~ One type of temperature control apparatus comprises a central unit which comprises a refrigeration circuit, which may be reversible and operated in a chilling mode and a heat pump ~ode for delivering cooling and/or heating to one or more remote units mounted in the zones of a building for controlling tt)e temperature of one or more zones of the building.
However, in generall such apparatus are restricted to e;ther supplying cooling or heating at any given time. In other words, the remote units would normally all be deliYering heating or cooling at the same time. It is not possible, in general, to provide a plurality of remote units connected to a single central ~0 un;t where the remote units can simultaneously, independently of each other supply heating and cooling to control the temperature of respective zones.

A further problem with such apparatus for heating and/or cool;ng WO 93~03311 P(~/IE92~00004 't~ .Ll~ '8 a bu;lding which compr;ses a central unit for supplyin~ heating and/or sooling to ~ remote uni$ or units is that such apparatus tend to be relatively inefficient in use. A particular problem with sush apparatus is that, in general, the central ~nit gener~tes heating or cooling at a rate which is,largely independent of the rate at which the remote unit or units is or are demanding hea~ing or oooling. This it w;ll be apprec;ated leads to eonsiderable loss and wastage of heat or cooling energy whioh is undesirable~

There is therefore a need for multi-zone ~emperature control appa~atus for co~trolling the temperature in one or more zones.
There is also a need for temperature con~rol apparatus for eontrolling the temperature of a single zone. Further, there is a need for a central unit for supplying a heat transfer medium to one or more remote units of such apparatus, and there is also a need for a remote unit for such apparatus. There is also a need for a ~ethod for controlling the energy output of the central unit.

The present ;nvent;on is directed towards proYiding such a multi~
zone temperature eontrol apparatus, such temperature control ~pparatus, such a central unit and a re~ote unit and a method.

Throughout th;s specificat;on, where reference is made to heat being transferred between a central unit and a remote unlt, it is to be understood that the heat may be transferred both ways or one way only between the central unit and remote unit. For example, heat is transferred to a remote unit when a central unit is supplying heating energy to the remo~e unit, and hea~ is transferred from the remote unit to the central unit when the central unit is supplying cooling energy to the remote unit~ In other words, when a central unit is operating in a chilling mode, cooling energy is supplied to a remote un;t, and accordingly, heat is being transferred from the remote unit to the central unit. On the other hand, when a central unit is operating in a ... , . . . . . ~ ~ ... . . . .

WO 93/03311 PCI'/IE92/0000'1 ~ 9 ~3 ~

heating mode for supplying heating to the remote unit, heat is being transferred from the central unit to the remote unit. The oentral unit may be prov;ded to operate in a ch;lling mode only, or in a heating mode only, or both. Further, reference to a refrigeration eircuit is to be understood ~o me~'~ eference ~o any such circu;t which may operate in a chilling mode for providing coolin~ or in a heating mode for providing heating or in both modes.

~h~
One object of the invention is to provide multi-zone temperature control apparatus which permits independent control of the temperature of different zones, and further, permits heating of one ~one while at the same time another zone is being cooled. It is also an object of the invention to provide suoh multi-zone heat oontrol apparatus which operates relatively effieientlyO and which can be installed at relatively low cost and with minimum inconven;ence.

Another object of the invention is to provide temperature control apparatus for controlling the temperature of at least one 20ne 20 whioh operates relatively efficiently, and which may be installed at relatively low cost with minimum inconvenience.
.
- - A further object of the invention is to provide a central unit for sueh tempe~ature eontrol apparatus or multi-zone kemperature control apparatus which operates relatively effic;ently, and whieh can be installed at a~relatively low cost and with minimum inconvenience. It is also an object of the invention to provide such a eentral unit ;n which the energy output de7ivered by the central unit can be matched to the demand for energy by a remote or remote unitO A further object of the invention is to provide a remote unit for such temperature control apparatus or multi-zone temperature control apparatus which operates relatively efficiently, and wh;ch can be installed at relatively low cost and with minimum inconvenience.

W0 93/03311 P(~r/lE92/00004 Another object of the invention ;s to provide a method for controlling the energy output of a oentral unit of temperature control apparatus so ~hat the energy output can be matched ~o the demand for energy from a remote or remote un;ts of the temperature control appara~us. ,' -Su~m3¢y_sf_the inventionAceording to the invention there 7s provided a central unit for supplying a heat transfer medium to at least one remote unit of temperature control apparatus for transferring heat between the central unit ~nd the remote uni~, the oentral unit comprising a refrigeration circuit having a refrigerant medium therein, the retrigeration c;rcu;t compr;sing a master heat exchanger for -:exc:hanging heat with the refrigerant medium, and a main heat ext:hanger for exchanging heat betwleen the refri~erant me!dium and th! heat transfer medium, a compressor means for compressins the refrigerant medium, and an expansion means for expanding the refrigerant medium, return tempera~ure monitoring ~eans for monitor;ng the return te~perature of the heat transfer n~edium returning to the main heat exchan~er, differentlating m~ans for 20 determiniflg the rate of change of the return temperature of the heat transfer Ined;um with respect to timel first control means responsive to the differlentiating means for controlling the energy OUtpllt of the refrlgeration circuit ln response to ~he rate of change of the return temperature of the heat transfer 25 medium with respect to time.

By proYidlng a control means which ;s responsive to the differentiating means for controlling the energy output of the refrigeratioll circuit in response to the rate of change of thé
return temperature of the heat transfer medillm with resp~ect to 30 time, the energy output of the cen~ral unit can be substlantially mat:ched to the demand for energy being placed on the central un;t, by one or more remote units. This leads to a relatively eff icient device and minimises energy wastageO

W O ~3/033ll PCTJIE92/000~4 Preferably, the f;rst control means varies the energy output of the refrigeration circuit; in response to a change in the rate of change of the return temperature of the heat ~ransfer medium with reslpects to t;me. Th;s perm;ts relatively accurate matching of 5 the energy output of the central unit to the d ~ -d for energy.

Adv,antageously, the f;rst control means is responsive to the rate of ehange of the return tempera~ure of the heat transfer medium witlh respect to time moving from one predetermined range of rates of change o~ return temperature to another range. By haYing the first control means responsive to th~ rate of ehange of the return temperature moving from one predetermined range to another, an apparatus which operates relative7y effic;ently is provided and frequent variations in the operation of the central unit are avoided.

In one embodiment of the invention the first control means is respons;Ye to the rate of change of the return temperature of the heat transfer ~ed;u~ with respect to time reaching a predetermined value. ~y having the first control means responsive to the rate of change of the return temperature of the heat transfer medium with respect to time reaehing a preldeter~ined value, particularly advantageous form of t:he ;nvention is prov;ded. The central unit according to the invention operates~particularly efficîently-and frequent variations in the ope~ation of the central unit are avo~ided.

In one embodiment of the ;nvention the f~rst control means comprises compressor cont~ol means for controllin~ the c:ompressor means ~or varying the energy output of the refr;geratiorl circuit.
By controlling the compressor means of the refri~eration circuit relatively effeGtive control of the central unit is pro~ided and matching of the energy output of the central to demand is relatively eff;ciently obtained.

Preferably, the compressor control means comprises mean!i for WO 93/0331 I c " PCI`/11E~2/00~0'1 controlling the m~rk/space ratio of a power supply beins delivered to the compressor means. By oontrolling the mark/space ratio of the power supply being del;vered to the co~pressor controller relatively eff;c;ent and effective control of the refrigeration circuit is achieved. ,~ _ Advantayeously, the coMpressor control means varies the mark~space ratio of the power supply to the compressor means inversely to the rate of ehange of the return temperature with respect to time. This provides relatively efficient and accurate means of controlling the oentral unit.

In one embodiment of the invention a circulating pump means f~r ciroulating the heat transfer medium ~hrough the main heat exchanger is provided, the first control means comprising pump control means for controlling the ~elivery of the pump means, the pump control means being responsive to the differentiating means for contrclling the delivery of the pump means in respon!se to the rate of changs of the return temperature of the heat transfer mediu~ to the ~ain heat exchanger with respect to time.
Controlling the pump means further facilitates eontrol of the 20 central unit for matching the energy sutput of the central un;t to the demand..

1n one embodiment of the invent;on the pump control means varies the delivery of the pump means inversely to the rate of change of the return temperature w;th respect to t;me. This provides relatively effieient means of controlling the circulat;on of the heat transfer medium which in turn facilitates ma~ching the energy output from the cental uni~ to the demand.

In one embodiment of the invention the first control means is responsive to the return temperature of the heat transfer medium~
By h~ving the first control means also responsive to the return temperature of the heat transfer medium, matching of the energy output of the central to the demand from the remote unit or units WO g3/03311 ~ 9 3 8 pcr/IE92/ol) is further facili~ated.

In one embodlment of the ;nvent;on the first control means is responsive to the return temperature of the heat transfer medium moving from one predetermined r~nge o~ return t~eratures to S another range. This provides a relatively effic;ent means of controlling the pump meanst and frequent variations in the operation of the central unit are avoided.

In one embodiment of the invention the compressor control means varies the mark/space ratio of the power supply to the compressor means proportionately to the t~mperature difference between the return temperature of the heat transfer medium and the flow temperature o~ the heat transfer medium flowing from the main heat exchan~er. This fur~her facilitates matching of the energy output of the central ~o ~he demand by the remote unit or uni~s.
,~
In a further embodiment of the in~ention the pump eontrol means varies the delivery of the pump me~ans proportionately to ~he d;fference between the re~urn temperature of the heat transfer medium and the flow temperature of the heat transfer medium flowing from the main heat exchanger. This provides a relatively efficient control means for the pump means.

Xn one embodiment o~ the i mention the-refrige~ation circuit is reversible and is operable in a chilling ~ode and a heat pump mode, and means for reversing operation of the refrigeration circuit bet~een the two modes is provided. The advantage of providing a reversible circuit is that a single central unit may be operated in a chilling mode for providing cooling to the remote unit and in a heat pump mode for pnoviding heat;ng to the remote unit.

Advantageously, the compressor means is a scroll compressor. It has been found that a scroll compressor is a relatively efficient compressor and is particularly suitable for control for varying wo s3/033~ 3 ~ P~ s2/00~04 the energy output of the ~cfrigeration circuit.

Preferably, the heat transfer medium is water. Where the heat transfer medium is water a relatively low cost and ef~icient apparatus is provided, and ~urthermore, the app~r~atus is environmentally friendly and does not provide a health hazard.

Additionally, the invention proYides a remote unit for receiving a heat transfer medium from a cen~ral uni~ of temperature control apparatus for transfernirlg heat between the central unit and the remote unit, the remot2 unit compris;ng a sec~ndary heat exchanger for exchanging heat wi~h the heat transfer medium, a booster heat delivery means, and a heat transfer means for transferring heat to or from the secondary hea~ exchan~er and the booster heat delivery means, air temp~rature monitoring means for ~onitoring the return temperature of air ~o the remote unit, and seeond control means responsive to the air temperature monitoring means for controlling the heat transfer means and for delivering a signal to the first control means for activating the central unit. The remote unit provides a relatively eff;cient apparatus for providing heating and/or cooling to a zone, and by virtue of the fact that a signal is transmitted from the remote unit to the eentral unit, the central unit reacts quicker than if the central unit were reliant solely on the flow and return temperatures of the heat transfer medium.

Further, the invention provides temperature eontrol apparatus comprising a central unit according to the inventi~n and a remote unit al~o according to the invention, the remote unit being connected to the central unit by a circulating eircuit for circulating a heat trans~er medîum between the central unit and the remote unit. The temperature control apparatus aecording to the ;nvention is a particularly efficient apparatus.

Further the invention provides multi-zone temperature control apparatus comprising a plurality of remote units, one remote unit 3 ~' being provided for each zone, a cen~ral unit for supplying a heat transfer medium to the remote units for transferring heat between the central unit and the respective remote units for controlling temperature of the zones, each central unit comprising a main heat exchanger for exchanging heat with the he~t~Eransfer medium, and first control means for controlling the central unit, each remote unit comprising a secondary heat exchanger for exchanging heat with the heat transfer medium, a heat transfer means for transferring heat between the secondary heat exchanger and the zone, air temperature monitoring means for monitoring the temperature o~ air in the zone, and second control means responsive to the air temperature monitoring means for controlling the heat transfer means and for deliYering a signal to the first control means for activating the central unlt in response to a change in temperature of the air, the apparatus further compris;ny a plurality of circulating circuits for communicating the secondary heat exchan~ers of respec~ive remo~e units w;th the main heat exchanger of the central unit for circulating the heat transfer medium between the main hea~
exchanger and the respective secondary heat exchan~ers, circulating means bein~ provided in respective circulating c;rcuits far circulating the heat transfer medium.

Th~ advantage of the multi-zone temperature control apparat~s according to the inv~ntion ~s that it permits the temperature ;n different zones to be controlled at different levels. It also permits independent control of the temperature in the zones relative to each other, and under certain condition, enables some zones to be heated while at the same time others are being cooled.

In one embodiment of the invention each circulating ~eans i5 responsive to the first control means. The advantage of having the circulating means responsive to the first control means is that relatively efficient control of the apparatus is achieved.

w o 93tO3311 pc~r/lEs2/oooo4 In another embodiment o~ the invention the heat transfer medillm is water. This pr~v;des a relatively low cost and eff;c;ent apparatus which is also environmentally friendly and does not present a health hazard, and furthermore may be relatively easily 5 ;nstal led. , ~

In another embodiment of the invent;on the circulatin~ c;rcuits are conneoted to the main heat exchanger independently of each other. This permits opera~ion of the remote units independently o~ each other.

10 In one embodiment of the invention each remote unit comprises a booster heat delivery means, the heat transfer means co-operating with the booster heat delivery means for transferring heat between the boos~er hea~ delivery means and the zoneO This permits some of the remote units to provide heating at the same time others of the remote units are providing cooling. For example, where the c:entr~l unit provides heating or cooling and the booster heat delivery means provides the alternative form of energy, ~he central unit may thus supply the remote units requiring the type of energy being supplied by the 20 central unit, while the other remote units can supply the alternative form of energy by means of the booster heat del;very - means. ~Additionally, the booster heat delivery means may supply additional energy i~ the central unit is unable to meet the demand.

Preferably, the booster heat delivery means is responsive to the second control means. This provides efficient control of the apparatus.

In ansther embodiment of the invention each booster heat del~very ~eans comprises a heat source. This permits th~ remote units to provide additional heat from the boos~er heat delivery means in the event that the central unit is unable to meet the demand for heating by the remote unit, either as a result of lack of . . .

WO 93/03311 pcr/lEg2/oooo4 3 3 ~

capacity, or the central unit bein~ in a chilling mode supplying cooling to another remote unit.

Advantageously, each booster heat delivery means is pnovided by an electrically powered heat source. This provi~es a relatively S efficient and easily installed remote unit.

Preferably, each secondary heat exchanger is provided by a coil heat exchanger. This leads to a relat;vely efficient remote unitO

Advanta~eously, each heat transfer means oomprises a fan. This provides a relatively eff icient remote unit.

P~eferably, the fan is elec~rically power~d. This provides a relat,vely efficient remote unit.

Advantageously, each circulating means comprises a circulating pump. This provides a relatively efficient apparatus.

15 Preferably, each circulating pump is an electrically powered variable speed circulating pump. This proYides a relatively efficient apparatus.

In one embodiment of the invèntion the air temperature monitoring means are mounted in the respective remote units for ~onitoring ZO the ~eturn air temperature of air returning to the respective remote units. Th;s provides a relatively efficient remote uni~
with a relatively quick response time.

In one embodiment of the invention the central unit comprises a refrigeration c;rcu;t having a refr;gerant medium therein and comprising the main heat exchanger for exchanging heat between the refrigerant medium and the heat transfer medium, a master heat exchanger for exchanging heat with the refrigerant medium, a compressor means for compressing the refrigerant medium and an WO 93/03311 P~/IE92~00004 î2 expansion ~eans for expanding the refrigerant mediu~, the refrigeration c;rcuit being responsi~e to the first control means. This provides a relatively efficient construction and operation of apparatus.

, ~
5 In another e~bodiment of the invention the refrigerat;on oircuit is reversible, and means for reversing the refrigeration circuit is proY;ded. The advantage of providing a reversible :~
refrigerat;on c;rcuit is that a single central unit ~ay provide cooling and heating energy.

Preferably, the multi-zone temperature oontrol apparatus comprises a central unit according ~o the invention. The advantage of prov;ding the multi-zone temperature apparatus with such a central unit is tha~ the energy output of the central unit can be matched to the demand of the remote units, and an 15 effioient apparatus is provided"

In one embodiment of the invention flow temperature monitoring means for monitoring the flow temperature of ~he heat transfer medium from the main heat exchanger ;s provided in each circulating oircuit~

In a further embodiment o~ the invention flow measuring means is provided in ~ach circulating circuit, the flow temperature monitorin~ means and flow measuring ~eans being connected to the first control means for enabling computation of the energy delivered to the secondary heat exchangers of the respective remote units. The advantage of providing flow measuring means in the eirculating circuits is that it provides for computation o~
the energy being supplied to the respective remote units.

The inven~ion also provides a method for controlling the energy output of a central unit of temperature control apparatus, wherein the central unit is of the type which supplies a heat transfer medium to at least one remote unit of the temperature WO 93/03311 PCI'/IE92/00004 control apparatus f~r transferring heat between the central unit and the remotc unitl and the central unit comprises a refrigeration circu;t hav;ng a refrigerant med;um therein, the refrigeration circuit comprising a master heat exchanger for S exehanging heat with the refrigerant medium, a~_a main heat :~
exchanger for exchanging heat between the refrigerant medium and the heat transfer medium, a compressor means for compressing the reFrigerant medium, and an expansion means for expanding the refrigerant medium, the method comprising the steps of determining the rate of change of the return temperature of the heat transfer medium returning to the main hea~ exch~nger with re~speet to time, and controlling the energy output of tlle refrigeration circuit irl response to the rate of change of the return temperature of the heat transfer medium. The advantage of the method is that it permits the energy ou~put of the cen~ral unit to be substantially matched to the demand from a remote or remote units.

In one embodiment of the invention ~he method comprises the step of varying the energy output of the refrigeration circuit in response to a ehange in the rate of change of the retur~l temperature of the heat transfer medium with respect ~o time.

In another embodilnent of the imention the energy output of the refrigerat;on circuit is varied ;n response to the rate of chanye of the return temperature of the heat transfer medium with 25 respect to time moving ~From one predetermined range of rates of change of return temperature.to another range.

In one embodiment of the invention the energy output of the -refrigeration circuit is var;ed in response to the rate of change of the return temperature of the heat transfer medium with 30 respect to time reaching a predetermined value.

Preferably, the method comprises the step of controlling the compressor means for varying the energy output of the wo 93Jo331 I PCr/IE92/1)0004 ' 8 refrigeration circuit.

In another e~bodiment of the invention the method oQmprises the step of controlling the mark/space ratio o~ a power supply being -;
delivered to the compressor means. ~ ~

Advantageously, the method colnprises the step of varying the ::
mark/space ratio of the power supply to the compressor means inversely to the r3te of change of the return temp~rature with res ect to time P

Advantageously, the method comprlses the step of varying the energy output of the refrigeration oircuit in response to a change in the return temperature of the heat transfer med;um.

Preferably, the method comprises the step of varying the energy output nf the refrigeration circuit in response to the return temperature of the heat transfer medium moving from one predetermined range of return ternperature to another range.

In one embodiment o~ the invention the method comprises the step of varying the mark/space ratio o~ the power supply to the compressor means proportionately to the temperature d;fference be~een the return telnperature of the he~t transfer medium and the flow temperatllre of the heat transfer medium flowing ~rom the main heat exchanger ~

In a further embodiment of the invention the method further comprises the steps of varyiny the rate of circulat;on of the heat transfer medium through the main heat exchan~er in response to the rate of change of the return temperature of the heat transfer medium to the main heat exehanger with respect to time.

~3~ . .. .
The adYanta~es of the invention are many. A particularly important advantage of the mult;-zone temperature control W O 93/0331l PCT/IE92/000~4 apparatus ;s that it permits independent control of the temperature ~f different ~ones. Furthermore, it permits heating of one or ~ore zones while at the sa~e t~me another or others of the zones are being eooled. Another advantage of the invention is that it permits the energy output of the cen~al unit to be substantially matched to the demand of the remote or remote un;ts. Furthermore, where a control unit is provided in temperature control apparatus with only one remote unit, the energy output of the central unit can be substantially matched t9 the demand of the remote uni~. Further, the invention provides a multi-zone temperature control apparatus which is relatively effi~ient to manufaeture, to install and to use. The apparatus is also relatively inexpensive and robust. Where ~he heat transfer medium is provided by water, a particularly environmentally friendly apparatus is provided, and furthermore, the apparatus does not present a health hazard and addi~ionally, the appa~atus can be readily easily installed in a building or other location. The central unit, the remote unit and the temperature control apparatus are also relatively efficient to manufacture, install and use, and can be provided a~ a relatively low cost4 Installation of the multi-zone temperature control apparatus and the temperature eontrol apparatus as well as the central unit and remote unit can be carried out with minimum inconvenience.

2~ The method according to the invention for controlling the energy output of the central is a particularly effeetive and effic;ent method for controlling such a central unit.

The ;nvention will be more clearly understood from the following description sf some preferred non-limiting embodiments thereof given by way of example only with reference to the accompanying drawings .

Br ef desc~iPtion~of the drawi~gs Fig. 1 is a schematic diagram of temperature control WO 93/03311 pcr/lEs2/oooo4 ? 8 apparatus aecording to the inYen~ion for space heating and/or cooling of a building for controlling the temperature of a zone of the building, Fig. 2 is a schematic diagram of portion o~ the temperature S control apparatus of Fig. 1 illustrated ;n a different mode of operation, Fig. 3 ~a~ and (b) is a f low ehart of a computer progrannne for controlling a remote unit of the apparatus of Fig, 1, Fig. 4 is a flow chart of a computer prograa~ne for controlling a central unit of the apparatus of Fige 1 Fig. ~ is a flow chart of a sub-routine of the computer progran~ne o~ Fig. 4, Fig. 6 is a flow chart of another sub~routine o~ the -~
computer programne of Fig. 4, -Fig. 7 is a schematic diagram of multi-zone temperature control apparatus according to the ;nYention for space heating and/or cooling of a plurality af zones in a :~
buildin~, and ~ ~

F;g. 8 is a perspective schematic diagram olF the apparatus of Fig. 7 installed in a building.

Referning to the drawings and initially to Figs. 1 to 6 there is illustrated temperature eontrol apparatus accord;ng to the invention indicated generally by the reference numeral 1 for 25 spaee heating and/or cooling a single zone in a building. The heat control apparatus 1 comprises a central ~nit 2 also aceording to the invention for supplyiny a heat transfer med;um, namely, water to a remote unit 3, also according to the wo 93/03311 PCT/IE92/000~4

3 8 1~
invention, for mounting in the zone of the building for heating and/or cooling the zone. A oirculating circuit 4 connects the cen~ral unit 2 ~nd ~he remote unit 3 fo~ circulating the heat transfer med;um between the units 2 and 3 as will be described belsw. The central unit 2 comprjses a reversib~_refri~eration circuit 8 which is operable in a chill;ng mode for xupplying cooling energy and in a heat pump mode for supplying heating energy from the central 2 to the remote unit 3~ A refrigerant medium, namely, freon gas is provided in ~he refrigeration eircuit 8~ The refrigeration c;rcuit 8 compr;ses a master heat exchanger 10 which in this case is provided by a fan assisted coil heat exchanger for exehanging heat between the refrigerant medium and the ambient air adjacent the central unit 2. A ~ain heat exchanger 11 in the refrigeration circuit 8 exchanges heat between the refrigerant medium and the heat transfer medium in the eirculatlng circuit 4. The main heat exchanger 11 is provided by a plate heat exchanger. A compressor means, namely, a compressor 12t in this ease a scroll compressor compresses the refrigerant medium. An expans;on means, namely, a pair of expansion valves 14 and 1~ are connected between the master heat exchanger 10 and the main heat exchan~er 11 for expanding the refrigerant medium. A rece;ver 16 between the expansion valve 14 and l5 receives and buff ers t~e expanded refrigerant mediumO
Bypass valves S and 6 connected in parallel with the expansion valves 14 and:15 are alternately opened so that one of the expansion valves 14 and 15 is bypassed and the other i5 operational depending on the mode of operation of the refr;gerat~on eircult 8. In a chill;ng mode the refrigerant medium is expanded through the expansion valve 14, while in a heat pump mode the refrigerant medium is expanded through the~
expansion valve 15. Reversing means for reversing the refrigeration eircuit 8 to operate in a chilling mode and in a heat pump mode comprises a reversing valve 18 which connects the master heat exchanger 10l the main heat exchanger 11 and the eompressor 17. When the refrigeratiQn circ~it 8 is to operate in the chilling mode the revers;ng valve 18 is configured as WO 93/03311 !PCI~/IE92/00004 illustrated in Fig. 1 and the flow of refrigerant medium through the refrigeration circuit 8 is in the di~ection of arrows A. In this configuration the master heat exehanger 10 acts as a condenser, and the main heat exchanger 11 acts as an evaporator, thus remoYing hea~ from the heat ~rans~er mediu~-in ~he main heat exchanger 11 for delivering cooling to the remote unlt 3~ When the refrigeration circuit 8 is operating in the heat pump mode the reversing valve 18 is configured as illustra~ed in FigO 2 and flow o~ the refri~erant medium throu~h the refrigeration circuit B is in the direction of ~he arrows ~. In ~he hea~ pump mode configuration, the master heat exchanger 10 acts as a evaporator and the main heat exchanger 11 acts as a condenser, thus transferring heat into the heat transfer medium circulating through the main heat exchanger 11, thus delivering heating to the remote unit 3. The reversing valYe 18 is opera~ed by a solenoid 13 under the control of a first control ~eans oomprising a first control circuit 25~ The first control circuit 25 compr;ses a microprocessor 26 which controls the soleno;d 13 under the control of a co~puter programme. The control circuit 25 and computer progra~me for controlling the micropr3cessor 2 ar~ described in more detail below. The reversing valve 18 is normally configured as ;llustrated in Fig. 2 with the refrigeration c.ircuit 8 operating in a heat pump mode. The ~icroprocessor 2~ controls the operation of the bypass valves 5 and 6 through solenoids 17 for switching the valves 5 and 6 on the operating mode of the reversing valves 18 being changed.

An electrically powered motor 20 drives the co~pressor 12. Power from a power supply unit 28 is delivered to the compressor motor 20 thro~gh a compressor control means, namely, a compressor 30 controller 29 for controlling the operation of the compressor 12 - ~:~
for enablin~ the heating and/or cooling energy output of the refrigeration circuit 8 to be varied to match the demand of the remote un;t 3. The compr2ssor controller 29 operates under the control of the microprocessor 26 as will be described below. The compressor controller 29 comprises means for varying the w o 93/03311 P ~ llEg2~00004 ~ark/space ratio of the power supply being delivered to the compressor motor 20 under the control of the microprocessor 26 for varyiny the energy output of the refrigeration circuit 8. In this case, the minimum mark/spaee cycle time is two ~inutes. The mini~um mark t;me ;s one minute and the minimum s~ce time is one minute. In other words, where the mark/space ratio is one the power supply is deliYered to the compressor motor 20 for one minute and is o ff for one minute. Needless to say, a cycle may be any length of time, for example, in the case of a mark/space ratio of 1:4 the cycle time would be five minutes, the power supply being delivered to the motor for one m;nute and off for four minutes~ The compressor controller 29 also permits eontinuous delivery of power to the compressor controller 20.

A variable speed electr;cally powered motor 19 driYes a fan 31 of the master heat exchanger 10. Power from the power supply 28 is delivered to the motor 19 through a motor csntroller 27 also under the control of the microprocessor 26. The fan 31 ;s operated at full speed when the refrigeration circuit 8 is operating in a heat pump mode for max;mising the delivery of ai~
through the master heat exchanger :L0 and in turn maximising heat transfer from the air into the refrigerant medium. When the refrigerat;on çircuit 8 is operat;ng in a ch;lling mode, the fan is operated to maintain the temperature of the liquid refrigerant medium leaving th~ master heat exehanger 10 at app~oximately 49C. Suitable temperature sensors (not shswn) connected to the microprocessor 26 are provided for monitoring the tempcrature of the liquid refriger~nt medium, and a suitable computer programme :~
(not shown or described~ is provided for controlling the ~otor controller 27. The control of such fans when a refrigeration-30 circuit is operating in a chilling mode will be well known to `~
those sk;lled in the art.

The circulating circuit 4 comprises a flow line 21 and a return line 22. Circulating means, namely a pump means comprising a variable output circulating pump 23 in the flow line 21 W O 93/03311 P ~ /IE92J00004 21~
circulates the heat transfer medium through the circulating circuit 4 and ;n turn through the main heat exchan~er 11. A
Yar~able speed electr;cally powered motor 24 drives the pump 23.
Power from the power supply Ullit 28 is delivered to the motor 24 5 through a pump control means, namely, a pump con~troller 30 for controlling the operation of the motor 24 and in turn the circulating pump 23 for varying the delivery nate at which the circulating pump 23 delivers the heat transfer medium through the circulat;ng i:irGUit 4. In this way the rate of delivery of 10 heating arld/or cooling energy from ~he eentral uni~ 2 to the remote unit 3 is var;ed to ma~eh the demand of ~he remote unit 3.
The pump controller 30 operates under ~he control of ~he mieroprocessor 26 and controls the motor 24 to operate at four different speeds, namely, speed one to speed four for operating the pump 23 at four different delivery rates. SPeed one is ~he fastest speed while speed four is the slowes~ sp~ed. Speeds two and three are intermediate speeds, speed two being faster than speed three. Accord~n~ly, when the motor 24 is operating at speed one the pump 23 is circulating the heat transfer medium at the highest delivery rate, while at speed four the pump 23 is circulating at the lowest delivery rate.

A return temperature monitor;ng means provided by a return temperature sensor 32 in the return line 22 adjacent the main heat exchanger ll monit~rs the return temperature TR f the heat transfer med;um returning to the main heat exchanger 11. A flow temperature monitoring means provided by a flow temperature sensor 33 in the tlow line ~1 adjacent the main heat exchanger 11 mon;tors the flow temperature of the heat transfer medium flowing from the main heat exchanger 11. The return temperature sensor 32 and f1ow temperature sensor 33 are connected to the mieroprocessor 26 so that the ~icroprocessor 26 can read ~he return and flow temperatures monitored by the sensors 32 and 33, respective1y. Differ@ntiating means comprising a differentiating circuit 34 is conne~ted to the return temperature sensor 32 for determining the rate of change of the return temperature of the ..... ... . .. ...

WO 93/03311 PCT/IE92/000~
3 ~

heat transfer medium w;th respect to time, namely, the ~/dt. The d;fferentiat;ng circu;t 34 is conneeted to the microprocessor 26 for enabling the microproeessor 26 ~o read the rate of change of the return temperature with respest to time.

The microprocessor 26 controls the compressor 12 through the compressor cantroller 29 for varying the energy output of the refrigerat;on circu;t 8 in response to the return temperature of the heat transfer medium monitored by ~he return temperature sensor 32 and the rate of change of the return tempera$~re determined by the differentiating circuit 34. The energy output of ~he refri~eration circuit 8 is varied inversely to the rate of change of the return temperature wi~h respect to time, and proportionately to the temperature d;fference between the return te!mperature monitored by the sensor 32 and ~he flow temperature o1 the heat transfer medium monitored by the flow tempe!rature s~!nsor 33. In other words, as the! temperature di~ference between the return and flow tenlpera~ures reduces, ~ha~ is the return temperature is moving t.owards the flow tempsrature, andl the rate of change of ~he return temperature 1s increasing, the supply of heating or cooling energy from the cen~ral unit exceedsi the deMand, and accordingly, the microprocessor 26 reduces the energy OlltpUt of the-refrigeration circuit 8. This en~bles the energy OlltpUt of the refrigeration circuit 8 to be var~ed to substantially Tnatch th~ de~and for hea~in~ or cooling e~nergy Z5 requ;red by the remote unit 3, thereby minimiz;ng wastage of h~eating or cooling energy. In this embodiment of the invention a~s will be deseribed belowj the energy output of the refrigerat;on c;rcuit 8 ;s varied as the temperature diff erence ble~ween the return and flow temperatures of the heat trans~er mledium moves from one range of temperatures to anotherl and as the rate of change of 1;he return temperature reaches a predeterm;ned value. As the rate of change of the return :~
temperature exceeds the predetermined value the energy output of the refrigeration circuit 8 is reduced, and where the rate o~
chanye o~ the return temperature falls below the predetermined ... . . . . . . . . . . .. . . . . .. .

WO 93/03311 P~/IE92/OB0041 value ~he energy output of the refrigera~ion circuit 8 is increased.

The microprocessor 26 also controls the cireulating pump 23 throu~h the pump controller 30 in response to t~e_return 5 temperature of the heat ~ransfer medium monitored by the return temperature sensor 32 and the rate of chan~e of the return ~emperature determined by ~he differentiating eircuit 34. The delivery rate o~ the pump 23 ;s varied inversely to the rate of ohange of the return temperature with respect to ti~e, and proportionately to the temperature difference between the return temperature monitored by the sensor 32 and the flow temperature monitored by the flow sensor 33 of ~he heat transfer medium. In other words, as the temperature difference betw~en the return and flow tempera~ures reduoes, that is ~he return temperature is ~oYing towards the flow temperature, and the rage of change of the return te~perature is increasing, the supply of heatins or coolins ener~y of the central unit 2 exceeds the demand of the remote unit 3, and accordingly, the microprocessor 26 reduces the delivery rate of the pump 23, thereby reducing the energy output being delivered from the refrigeration circuit &. This fur~her enables the energy output of the central unit 2 to be substantially matched to the demand for heating or cooling energy required by the remote unit 3. Accordingly, wastage of heating or cooling energy from the control unit 2 is further miniloised.
~5 In this embodiment of the invention as will be describ~ed in more detail below, the delivery rate of the circul~ting pump 23 is varied as the returr7 temper~ture of the heat transfer Imedium moves from one range of rPturn temperatures to another, and as the rate of change of the return temperature reaches a 30 predete~mined value, which in this embodiment of ~he invention is different to the predetermined value at which the energy output of the refrigeration circult 8 is varied. Needless to say, in many cases, it is envisa~ed that ~he predetermined value of the rate of change of the return temperature to which the circulating 35 pump 23 is responsive and the refrigeratiorl circuit 8 is WO ~3/03311 PCr/IE92/00~04 responsive may be the same.

When the central unit 2 is supplying cooling to the remote unit 3, in other words, the refrigeration circuit 8 i~s operating ;n a chilling mode, the flow temperature of the heat,tr~nsfer med;um 5 from the main heat exchanger 11 is approximately 4C. When the central unit 2 is supplying heating to the remote unit 3, in other words, the refrigeration circui~ 8 is operating in a heat pump model the flow temperature of the heat transfer medium from the main heat exchanger 11 is approximately 45C. The return 10 temperature of the heat transfer medium to the main heat exchanger 11 depends on the demand for cooling or hea~ing by the remote unit 3. In the case of a high deman~, the temperature difference between the flow and return temperatures is relat;vely high, while in the case of a rela~ively low demand the 15 temperature difference between the flow and return temper~tures of the heat transfer medium is relatively low. In other words, the rcturn temperature approaches the flow temperature.
Addit;onally, where the rate of change of the return ~elnperature is high as it ;s moving towards the value of the flow 20 temperature, the supply sf energy from the central unit 2 is exceeding demand from the remote unit 3 and may be redueed.

Where the central unit ~ is deliYering cooling, and the return temperature of the heat transfer medium is greater than 1ûC~ in other words, 6C above the flow temperature of 4~C, the demand for cooling is high, and the compressor controller 29 sets the mark~spaee rat;o so that the compressor 12 runs continuously.
Where the return temperature of the heat transfer ~ed;um lies in the ran~e between 7C and 10C, ~nd the rate of change of the return temperature is less than the predetermined value of 2C
per minute, the supply of cooling energy considerably exceeds demand, and the compressor controller 29 sets the mark/space ratio so that the compressor 12 runs continuously. On the other hand, where the return temperature sf the heat transfer medium lies between 7C and 10C and the rate of change of the return WO93/03311 s ~ P~/IE92/OOOOql temperature is greater than or equal to the predetermined value of 2C per minute, the demand for cooling is not qu;te so high~
and the compressor controller 29 sets the mark/space ratio at 1:2 so that the compressor runs for one minute and is off for two minutes for each three minute cycle. This thus,providîng a lower cooling output from the centnal unit 2 to match the lower demand for cooling from the remote un;~ 3. Where the return temperature of the heat transfer medium lies in the range between 5C and 7C
and the rate of change of the return temperature is less than 2C
lO per minute, the compressor controller 29 sets the mark/space ratio at 1:2 thus the compressor 12 runs for one ~inute and is off for two minutes. On the other hand, where the return temperature of the heat transfer medium lies in the range between 5C and 7C and the rate of chan~e of the return temperature is 15 greater than or equal to 2~C per minute, thus indicating a lower ~-demand for cooling, the compressor controller sets the mark/space ratio at 1:3. In other words, the compresscr is on for one minute out of every four minutes. Where the return temperature of the heat transfer medium lies in the range between 4C and 5~C
and the rate of change of the return temperature is less than 2C
per nlinute, thus indicating a reasonable demand for cooling, the compressor control~er 29 sets the mark/space ratio 1:2. On the other hand, where the return temperature of the heat transfer medium lies in the range between 4C and 5C and the rate of ~5 change of the retllrn temperature is greater than or equal to 2C
per minutel thus indicating a relat;vely low demand for heat, the compressor contro11er sets the mark/space ratio at 1:4. Thus, the compressor 12 is operated for one minute in every five minutes. Where the return temperature of the heat transfer medium is less than or equal to 4C the compresssr controller 29 ceases to deliver power to the compressor motor 20 $hereby switching off the compressor 12.

Additionally, as mentioned above the delivery rate o~ the circulating pump 23 ;s varied to meet the demand for heating or cooling of th~ remote unit 3. For example, where the central WO g3/0331 I P~ 9~JOOû04 2~
unit 2 is supplyin~ cooling and the return temperature of the heat transfer medium is greater than 10C, thus indicating a hi~h demand for eoolin~, the pump controller 30 operates the pump 23 at speed one, namely, m~ximum speed. Where the return 5 temperature of the heat transfer medium lies inl-~ range between 7~C and 10C and the rate of ehange of the return temperature is less than the predetermined value of 3C per minute, thus ;ndicating a high demand for cooling, the pump controller 30 operates the pump 23 at speed one. Where the return temperature lQ of the heat transfer medium lies in the range between 7C and 10C and the rate of change of the return temperature ;s greater than or equal to the predetermined Yalue of 3~ per minute, thus indicating a lower demand for cool;ng, the pump controller 30 operates the pump 23 at speed two. Where the return temperature 15 of the heat translFer medium lies in the range between 5C and 7C
and the rate o~ change of the return ~emperature ;s less than 3C
per m;nute the pump controller operates ~he pump 23 at speed two.
Where the return temperature of the heat transfer ~edium lies in the range between 5~C and 7C and the rate of change of the return temperature is greater than or equal ~o 3C per minute thus indic~ting a s~îll lower demand for cooling by the remote un;t 3, the pump controller 30 operates the pump 23 at speed 3.
Where the return temperature of the heat transfer medium lies in the range bet~een 4C and 5C thus indicating a relatively l~w demand for cooling from the remote unit 3; the pump controller 30 operates the pump 23 at speed four, namely, the minimum speed.
Where the return temper ture of the heat transfer medium is less than or equ~l to 4C the pump eontroller 30 switches off the pump 23, When the eentral unit 2 is operating to s~pply heating to the remote unit 3, in other words, when the refrigeration circuit 8 is operating in a heat pump mode, similar control of the compressor 12 and pump 23 is exercised. The operation of the compressor 12 and pump 23 when the return temperature of the heat transfer medium is less than 37C, in other words, 8C below the WO 93/03311 P~/IE92/00004 ~L'~L~938 ,,,"~

7~
flow temperature, the compres~or 12 and pump 23 are controlled in similar fashion as when the return temperature is lO~C when the central unit 2 is supplying coolingO When the return temperature of the heat transfer medium lies in the range between 40C and 37C the control of the compressor 12 and pump 2~ is similar to that when the return temperature lies in the range between 7C
and lO~C when the eentral unit 2 is supplying cooling. The re$urn temperature of the heat transfer medium lying in the range between 43C and 40C corresponds to the range of 5C and 79C
when the central unit is supplying cooling. The return ~emperature of the heat transfer mediu~ lying in the range between 45C and 43~C corresponds to the range of 4C and ~C
when the central uni~ is supplying cooling. When the return temperature of heat transfer medium is greater than or equal to 45C the compressor 12 and pump 23 are shut off. The operation of the microprocessor 26 under the control nf the comp~ter programme controlling the compressor 12 and c;rculat;ng pump 23 is deseribed in more detail below with reference to the flow charts of FigsO 4, 5 and 6.

The refrigeration oircuit 8 and the first control cireuit 25 as well as the circulating pump 23 and pump motor 24 are housed in a single housing (not shown), but indicated by the broken line 48 of Fig. 1. - ~
.. . . . . .
: Returning nnw to the remote unit 3, the re~ote unit 3 comprises a secondary heat exchanger 36, in this case a coil heat exchanger which i~ connected to the c~irculating circuit 14 for receiYing the heat transfer medium~ and for exchanging heat between the heat transfer medium and the ambient air in the zone. A booster heat delivery means comprising an electrically powered resistance wire heater 37 in the remote unit 3 delivers heat to the zone in the event that the central unit 2 may be supplying cooling, or the seeondary heat exchanger 36 cannot cope with the demand fon he~t from the zone. A heat transfer means comprising a variable speed electrically powered fan 38 mounted in the remote unit 3 WC~ 93/03311 pcr/lEs2/oooo4 transfers heat between the secondary heat exchanger 36 and the zone, and the heater 37 and the zone.

A second control means, namely, a second control cirouit 39 comprising a microprocessor 40 controls the ope~a~ion of the remote un;t 3 in response to the temperature of the amb;ent air being returned to the remote unit 3, and ac~iva~es the central unit 2 through a eommunicating means, namely, a cable 35 connected between the microprocessors 26 and 40 to supply heating or cooling whichcver is required. The mieroproc~ssor 40 operates lQ under the control of a computer progra~me which is described below with reference to ~he flow chart of Fig. 3. An ambient air temperature monitoring means comprising an air temperature sensor 41 is mounted in the remote unit 3 adjaeent the fan 38 for monitoring the return air tempera~ture of ambient air being returned to the remote un;t 3. The air temperature sensor 41 ;s connected to the microprocessor 40. A power supply unit 42 in the remote unit 3 delive~s electrical power ~o the fan 38 and the ~:
heater 37 through a fan controller 43 and a heater controller 44 which operates under the control of the microprocessor 40. The fan controller 43 under the control of the microprocessor 40 operates the fan 38 at three speeds for varying the output of hcating or coo.l;ng from the remote unit 3 to the zone. The heater c~ntroller 48 under the control of the microprocessor 40 varies the markJspace ratio of power being supplied to the heater 37 from the power supply unit 42 for varying the heat output of the heater 37.

A keypad 45 haviny a visual display 46 i~ connected to the microprocessor 40 ~or enabling a set point te~perature about-which the temperature of the zone is to be controlled to be inpu~ed into the microprocessor 40. The keypad 45 may be mounted or the remote unit 3 or may be provided for mount;ng in the zone at a convenient locationO On the temperature of the ambient air being monitored by the sensor 41 exceed;ng the set point temperature by 1C or dropping below the set point wa, 93/(13311 P~/IE92/lD0004 temperature by 1C, the microproeessor 40 operates the remote unit 3 and delivers a signal to the microprocessor 2S ;n the central unit to act;vate th~ central unit 2 to deliver heat;ng or oooling, whichever is required.

The secondary heat exchanger 36l the heater 37 and fan 38, as well as the control circuit 39 and the air temperature sensor 41 are mounted in a housing which is not shown but is illustrated by the broken line 47.

Referring now to Fig. 3(a~ and 3(b) ~here is illus~rated a flow chart of a computer programme under which the microproeessor 40 operates for controlling the operation of the remo~e unit 3.
Block 300 in Fig. 3(a~ of the flow chart commences operation of the computer programme. Blook 301 reads ~he set point temperature which is stored in the mieroprocessor 40 after being entered through the keypad 45. Block 302 reads the ambient ~emperature from the air temperature sensor ~1. Bloek 303 co~pares the ambien~ temperature read by block 3C2 wi~h the set point temperature read by block 301. If the ambient temperature is greater than or equal to 1C above the set point temperature, cooling is required in the zone, and the computer programme moves to block 304 which will be described shortly. If the ambient temperature is not greater than or equal to 1C above the set point temperature, the eomputer programme moYes to block 305 which cheeks if the ~mbient temperature is greater than or equal 2~ to 1C below the set point temperature. Should block 305 determine that the ambient temperature is greater than or egual to 1C below the set point temperature heating of the zone is required, and the computer programme moves to block 306 wh;ch in turn moves the co~puter programme to block 307 which is described below~ On the other hand, should block 305 determine that the ambient tempera$ure is not greater than or equal to 1C below the set point temp~rature the computer programme is returned to block 3~1.

WO 93/033111 p~cr/IE9~/oooo4 3 ~ :

Returning now to blook 304, block 3M trans~its a reque~st from the microprocessor 40 to the microprocessor 26 of the ol ntral unit 2 requesting cooling. The computer programne then moves to bloek 308 which causes the microprocessor 40 to eontroll the fan 5 controller 43 to operate the fan 38 at its low~d~ The computer pro~ramme then moves to block 3û9 which checksi if the ambient temperature monito~ed by the air temperature sensor 41 is less than or equal to 2C above the set point temperature~ If the ambient temperature is less than or equal to 2C above the set point temperature the computer progra~ne moves to b10ck 310 which causes the microprocessor 40 to operate the fan c:ontroller 43 to run the fan 38 a1; the medium speed and the comput;er programme is moved to block 311 which is described below~ On the other hand, should block 309 determine that the ambient 1~ temperature is greater than 2C above the set point temlperature, the computer programme is moved ~o block 31Z which caus,es the microprocessor 4 to operate ~he fan controller 43 to run the fan 38 at ;ts high speed. The computer programme then moves to block 3~ lock 311 again reads the an1bient temperature and moves ~o block 313 which checks if the ambient temperature is less than or elqual to 1C above the set point temperature. If block 313 determines that the ambient temperature is less than or equal to l~DC aboYe the set point temperature, the computer progra~e moves to block 314 which causes the microprocessor 40 to operate the ` 2~ f~n controller 43 to run the fan 38 at its low speed and the computer programme moves to black 315. Block 315 chechs if the ambient temperature read by block 311 is less than or equal to tlle set point tempera~ure, and if so, the computer pro!aramme moves to block 316 which causes the m;croprocessor 40 to transmit a request to the microprocessor 26 of the central unit 2 cancelling the request for cooling. The computer programme then returns to block 301. On the other hand should bloek 313 have determined that the ambient temperature is not less than or equal to 1C above the set point temperature, the computer programme is returned to block 309. I~ block 315 determines that the ambient temperature is greater than the set point temperature, the Wo 93/0331l pcr/IE92/oooo4 computer programme moves to block 311.

Referring now to Fig. 3~b) the part of the co~puter programme o~
the microprocessor 40 which oontrols the remote unit 3 in the event of a requirement for heating of the zone w~Jl now be described. Block 307 transmits a request from the ~icroprocessor 40 to the microprocessor 26 of the eentral unit 2 for heating.
The computer programme then moves to block 317 which causes the microprocessor 40 to operate the fan controller 43 to run the fan 38 at its 1GW speed. The computer programme then moves to block 318 which checks if the ambient temperature read by blook 302 ;s less than or equal to 2C below the set point temperature. If the ambient temperature is less than or equal to 2~C below the set point temperature the computer programme moves tQ block 219 which causes the microprocessor 40 to operate the fan controller ~5 43 to run the ~an 38 at the medium speed. On the other handl if the ambient temperature is determined by block 318 to k~e ~reater than 2C below the set point temp*rature the computer programme moves to block 320 which causes the microprocessor 40 to operate the fan controller 43 to run the fan 38 at high speed. A~ter passiny to block 319 or block 320 the computer progranmle ~hen moves to block 321 which reads the ambient temperature ~rom the air temperature senscr 41 and the computer programme moves to block 3Z. Block 322 chscks if the a~bient temperature is greater than 2C below the set point temperature, and if so ~he computer programme moves to block 3230 If block 3 Z de!tgrmines ~hat the ambient temperature is less than or e~ual to 2'C below ~he set point te~perature the computer programme moves to block 324 which will be deseribed below. Block 323 checks if the ambient temperature is less ~han or equal to 2.5C below the set point temperature. If so, the computer programme moves to block 325 which eauses the micr~processor 40 to control the hleater controller 44 to run the electrically powered heater 37' at a mark/space ratio of 40%. Should block 323 determine thlat the ambient temperature is greater than 2.5C below the set po;nt temperature the computer programme moves to block 326 which WO 93/03311 P~/IE92/001104 q 3 ~

checks if the ambient temperature is greater than or equal to 5~C
below the set point temperature. If so, the computer progra~me moves to block 327 which causes the microprocessor 40 to operate the heater controller 44 to run the heater 37 continuously.
Should bloek 326 determine that the ambient te~pe~ature is less than 5~ below the set point temperature, the computer progra~me is moved to block 32B which causes the microprocessor 40 to control the heater con~roller 44 a~ a mark/space ratio between 40% and continuous running whieh is proportional to the amount by which th~ ambient temperature is below ghe set point temperature between to 2.5C and 5C. The computer programme after pass;ng throu~h blocks 325, 327 or 328 then returns to block 321.

Returning now to block 324, shoulcl block 324 determine that the ambient temperature is less than or e~ual to 1~C below the set point temperature, the eomputer progral.~e is moved to block 329 which causes the fan controller 43 to run the fan 38 at its low ~:
speed. The computer programme then moves to block 330 which checks if the ambient temperature is greater than or equal to the set point temperature. If so, the eompu~er programme moves to block 331 which causes the microprocessor 40 to transmlt a-request to the microprocessor 26 of the central unit to cancel the request for heating ~nd the co~puter programme then moves to block 332 which returns the programme to block 301~ In the event ~hat block 324 determines that the ~mbi~nt te~pera~ure is greater - 25 than 1~C b~low the set point temperature the computer programme moves to bloek 3331 which returns the csmputer progra~me to block 303. In the event that bluck 330 determines that the ambient temperature is less than the set po;nt temperature, the computer pro~ramme is returned to block 321.

Referring now to Fig. 4 a flow chart of the main computer progra~me which controls the operation of the microprocessor 26 of the central unit 2 for controlling the central unit 2 is illustrated. Block 400 of the flow chart starts the computer programme. The computer programme then moves to block 401 which WO 93/03311 P~/IE92/OOOlM
9 ~3 8 j- l .
3~
checks if there i5 a request from the microprocessor 40 of the remote unit 3 ~or heating or oooling. If no request has been reeeived the oamputer progra~ane moves to block 402 which puts the microprocessor-~6 to sleep to await an interrupt which returns the computer programne to block 401. On block ,4~L determining that there has been a request for heating or cooling from the remote unit 3 the computer progranune moves the block 403 which causes the microprocessor 26 to operate the pump controller 30 to operate the circulating pump 23 at speed number one, namely, its highest speed for cireulating heat transfer medium throuyh the circulating circuit 4 to the remote unit 3. The computer prograTr~ne then moves to block 404 which checks if the request from the rem~te unit 3 is for cooling. If so the computer progrannne moves to block 405. Whi le on the other hand, if the request is for heating the ~omputer progranune moves to block 406.
Block 406 will be dealt with belowO Returning to block 405, block 405 times a tilne delay of onf~ m;nute and then t~e computer programme moYes to blocl( 407 which activates the reversing valve 18 for operating the refrigeration circuit 8 in a chillin~ mode and thc computer programne moves to block 408. Block 408 times a further delay of thirty seconds and moves the computer progranDe onto block 4û9 which causes the microprocessor 26 to operate the colnpressor controller 29 to switch on the compressor 12 to run continuously. The computer programme then moves to block 410 which checks i~ the request for cooling from the remote u~;t 3 has been cancelled.- If so the computer programme moves to block 411 whi~h switches off the compressor 12 and in turn moves to block 412 whieh returns the computer program~e to the st2rt block 400. Should the block 410 determine that the request for cooling from the remote unit has not been cancelled the computer programme moves to block 413 which reads the return temperature of the heat transfer medium in the return line 22 from the return temperature sensor 32 and the computer programme moves to block 430 which reads the numerical value of dT/dt from the differentiating circuit 34. The computer pro~ramme moves to block 414 which calls up sub-routine 1 which will be described WO 93/03311 PCI'/IE92/00004 3 ~

below with reference to Fig. 5. Sub-routine 1 controls the operation of the compressor 12 and the pump 23 in response to the return temperature of the heat transfer medium to the main heat exchanger 11 and the rate of cha~ge of the return temperature with respects to time as will be described below~

Returning now to block 406. Block 406 times a time delay of one m;nute and moves the computer programme to block 415. Block 415 operates the reversing valve 18 so that the refrigeration circuit 8 operates in a heat pump mode for delivering heat to the remote un;t 3~ The computer programme then moves to block 416 which times a further thirty second delay and moves the computer programme onto block 417 which swi~ches on the compressor in the same fashion as block 499. The computer programme ~hen moves to block 418 which ohecks if the request for heating by the remote unit 3 has been cancelled. If 50, ~he computer programme moves to block 411 and in turn to block 41? both of which have already been described. In the event that the request for heating in the remnte unit 3 has no~ been cancelled the computer programme moves to block 419 which reads the return temperature of the heat transfer medium from the return temperature sensor 32 and then proceeds to block 431. Block 431 reads the numerical value of dT/dt from the~d;fferentia~ing circui~ 34. The computer progr~mme then moves to block 420 which calls up sub-rout;ne number 2 which is illustrated in Fig. 6. ~u~-routine number 2 controls the 2~ operation of the compressor 12 and the pump 23 in response to t~e return temperature of the heat trans~er medium and the rate of ehange of the return temperature with respect to time, as will be descr;bed below.

Referring now to Fig. 5 sub-routine 1 of the computer programme will now be described. Block 500 starts sub-routine 1 and the computer programme moves to block 501. Block 501 checks if the return temperature of the heat transfer medium read by block 413 is greater than 10C. I~ so, the computer programme moves to block 502 which causes the microprocessor 26 to operate the WO ~3/03311 PCr/lE92/000~

compressor controller 29 to run the compressor motor 20 continuously thereby operating the compressor 12 con~inuously.
The computer progran~ne then moves to block 503 which causes the microprocessor 26 to operate the pump controller 30 to run the pump motor 24 a~ speed one, namely, i~s maximum~peed thereby running the pump 23 at its maximum speed for maximum delivery of the heat transf~r medium through the circulating circu;t 4. The computer programme ~hen moves to block 504 which returns control of the microprocessor 26 to block 413 of the main computer progra~me of Fi~. 3. Should block 501 de~ermine that the return temp~rature read by the return temperature sensor 32 is greater than 7C but less ~han or equal to 10C the computer programme moves to block 506. Block 506 checks if the numerical value of ~/dt read by block 430 is yreater than or e~ual to 2C per minute. If so, the computer programme moves to blook 507 which causes the mîcroprocessor 26 to control the compress~r controller 29 to deliver power to the eompressor motor 20 with a mark/space ratio 1:2~ The computer programme then moves to block 508 which checks if the numerical value of ~tdt is greater than or equal to 3~C per minute. If so, the computer programme moves to block 509 which causes the ~icroprocessor 26 to operate the pump controller 30 for operating the pump motor 23 and in turn the pump 23 at speed number two. The oomputer programme then moves to block 504. In the event that block ~06 determines that the numerical value o~ tT/dt is less than 2C per minute, the computer programme moves to block ~10 which operates the compressor controller 30 to run the compressor motor 20 continuously, and in turn the compressor 12 continuously. The computer programme moves to block 51~ which causes the m;croprocessor 26 to operate the pump controller 30 to run the pump motor 24 at speed one and in turn the pump 23 ;s operated at the max;mum delivery rate~ The computer programme then moves to block 504 which has already been described. Should block 508 determine that the numer;cal value of dT/dt is less than 3C per minute~ the computer programme moves to block 511 which has just been described.

WO 93/03311 PCll~/IE92/00004 In the event that block 505 determines that the return temperature does not lie between 7C and 10C the computer programme moves to blo~k 512. Blook 512 ohecks ;f the return temperature is greater than 5C and less than or equal to 7~C.
If so, the computer programme moves to block 5~_which cheeks if the numerical v~lue f ~/dt iS greater than or equal to 2C per minute. If so, the computer programme moves to block ~14 which causes the microprocessor 26 ~o control the compressor eontroller ~9 to deliver power to the compressor motor 20 at a mark/space ratio 1:3. The computer programme then moves to block 515 which checks if the numerical value of dT/dt is greater than or equal to 3C per minute. If so, the computer programme moves to block 516 which causes the microprocessor ~6 to operate the pump controller 30 to run the pump motor 24 at speed three and in turn the 1~ c;rculating pump 23 is operated at speed three. The computer pro~ramme then moves to block 504 which has already been desoribed. Should block 513 determine that the value f ~/dt iS
less than 2~C per minute, the computer programme moves to block 517 whieh eauses the microprocess~Dr 26 ~o oontrol the eompressor controller 29 for delivering power to the compressor motor 20 with a mark/space ratio of 1:2. The computer programme then moves to block 518 which causes the microprocessor 26 to operate the pump cont~oller 30 for running the pump motsr 24 at speed two and ;n turn the c;rculating pu~p 23 at speed two. The computer programme then ~o~es-to block 504. Should block 515 determine that the numerical value of ~/dt iS less than 3C pcr minutel the computer pro~ramme moves to block 518 which has just been described.

In the event that bloek 512 determines that the return temp rature does not lie between ~C and 7C the computer programme moves to block 519 which cheeks if the return ~emperature is greater than 4C and less than or equal to 5C.
If so, the computer programme moves to block 520 which checks if the numerical value of ~Jdt is greater than or equal to 2C per minute~ If so the computer programme moves to block 521 which W O 93/0331l pc~r/lEs2/oooo4 ~ ~ :L ~ ~ 3 8 3~
causes the microprocessor 2h to opera~e the compressor controller 29 to deliver power to the compressor motor 20 with a mark/space ratio 1:4. The computer programme then moves to block 527 whi~h causes the microprocessor 26 to operate the pump controller 30 ~or running the pump motor 24 at speed four, n~eLy, the minimum speed and ;n turn run the circulating pump 23 a~ its minimum delivery rate. The computer pr3gramme then moves to block 504 which has already been described. 5hould block 520 determine that the numerical value of dT/dt is less than 2C per minute, the computer programme moves to block 523 which causes the microproeessor 26 to operate the compressor controller 29 for delivering power to ~he compressor mo~or 20 with a mark/space ratio of 1:2 thereby op~rating ~he eompressor 12 with a mark/space ratio of 1:2. The computer programme then moves to block 522 which has just been described.

In the event that block 519 determines that the return temperature of the heat transfer mediu~ does not lie between 4C
and 5C, the eomputer programme ~aves to block 524. Block 524 checks if the temperature is less than or equal to 4C~ If block 524 determines that the return temperature is less than or equal to 4C the computer programme moves to block 5?5 which ca~ses the microprocessor.26 to operate the comprcssor controller 29 to swltch off the compressor ~otor 20 and in turn the compressor 12.
` The computer programme then moves to block 526 whi~h causes the microprocessor 26 to operate the pump controller 30 for runniny the pump motor 24 at speed 4. The computer programme then moves to block 5Z7 which returns the control of the microprocessor 26 to the main computer pro~ramme of Fig. 4 by returning to the start block 400. If block 524 determinss that the return temperature is greater than 4C the computer programme moves to block 530. Block 530 causes the microproeessor 26 to operate the compressor controller 29 to deliver power to the compressor motor 20 with a mark/space ratio of 1:4. Block 530 also causes the microprocessor 26 to operate the pump controller 30 to run the pump motor 24 at speed four. The computer programme then moves wo 93~0331 ~ L~l ~ 3 8 ~Cr/lEs2/o~oo~

to block 531 which reads the return temperature of the heat trallsfer med;um and returns the computer progrannne to block 5~4.

Referring now to Fig~ 6 the flow ehart of sub-routine number 2 of the main computer programllle is illustrated. The ~low chart of the sub-routine number two is subs~an~ially similar ~o lEhe flow chart of the sub-routine number 1 and ~imilar blocks are identified by the same reference numerals. ~ub rout;ne number 2 is called up by block 420 of the main flow chart of Fig. 1 when ~he! remote unit 3 ;s calling for heating from the central unit 2.
Thuls, the only blocks which are different in sub-rout;ne nurnber 2 to those in sub-routine number 1 are blocks 50l, 504, 505, ~02, 519 and 524. Accordingly, only the equivalent to these blocks in sub-routine number 2 will be desoribed. Block 600 starts sub- :
rolltine number 2. Block 601 checks if the return temperature of th~ heat transfer medium read by block 419 from the retlurn :-terlperature sensor 32 is less th~n 37C. If the return tefllperature is less than 37C the com,nuter progrannne ~oves to bll~ck 502. On the other hand, the computer programme movas to block 605 which checks if the return temperature is less than 40'~C and greater than or equal to 37C. If so, the computer ~;
programne moves to block 506. On the other hand, the computer progran~ne mov~s to block 612 which checks if the return telnperature is less than 42C and greater than 40C. If so, the colnputer programme moves to.block 513. On the other hand, the ~:
2~ col~puter progra~ne In~ves to block 619 which checks if the return temperature is less than 45C and greater than or equal to 43C., If so, the computer progranane moves to block 520~ If rot, the computer progranane moves to block 624 which checks if the return temperature is grea~er than or equal to 45C. If so, t.he :~
computer progrannne moves to block 525. If not, the computer progranDne moves to block 530. On the sub-routine movirlg to block ~:
604 which is equivalent to block 504 of sub-routine 1, the sub-rout;ne 2 ;s returned to block 419 of Fig. 4. In the c:ase of blocks 506, 513, 520, 508, 515 and 522 these blocks che!ck the value olF dTIdt read by block 431.

WO 93~03311 PCME92/00004 In use, the apparatus 1 is mounted ifl a building, in gen~eral, with the central unit 2 mounted exteriorly of the buildingt generally, ;n a covered location, but with sufficient ventilation to permit the passage of air e~ficien~ly over the m~er heat exchanger 10 for efficient running of the refri~e~t;on circuit 8 whether running in a chilling mode or in a heat pump modeO The remofe unit 3 is mounted in a sui~able lacation in the zone for heating or cool;ng the zone. The remote un;t 3 may be ~ounted on :-a wall, eeiling, or the like or may be free standing on a floor, The keypad 45 may be mounted on the remote uni~ 3 or may be mounted in any other suitable or desir~ble location in the zone :~for easy access by an occupant. The power supply units :'8 and 42 are connected to a suitable mains electricity power supply.
,..
An occupan~ of the zone enters the desired set point temperature through the keypad 45 at which the ambient ~emperatu~e olF the zone is to be mainta;ned~ The entered set point is displayed on ~:the visual display 46 for verification. The microprocessor 40 of the remote unit 3 under the control of the computer prog7Oamme described with referenGe to Fi~. 3 monitors the ambient temperature by reading the air temperature sensor 41~ On the air temperature exceed;ng the set point temperature by 1C 01' falling bel~Dw the set ~oint temperature by 1C the microprocessor 40 under the control of the computer programme of Fig. 3 operat~s the remote unit 3 as already described and transmits a s-ignal to 2~ the central unit 2 requesting heating or cooling. The central unit 2 on receiving the request for heating ar cooling as the cas~ may be operates und~r ~he control of the computer programme and sub-routines 1 and 2 of Figs. 4 to 6 for delivering cooling or heating to the remote unit 3.

Referring now to Figs~ 7 and 8 there is illustrated multi-zone heat control apparatus ac:cording to the inYention indicated generally by the reference numeral 50 for eontrolling thle temperature in a pluralit;y of ~ones 51 in a building 52. In Fig.
8 f/~ur zones 51 are illustrated. The apparatus 50 comprises one wo 93/03311 Pclr/lE92/00004 9 r) ~

central uni~ 2 substantially of the type descn;bed with reference to Figs. 1 to 6 and a plurality of remote units 3, namely, four realote units 3a to 3do one in each zone 51. The remote units 3a to 3d are similar to those described with reference to l igs. 1 to 5 6, and may be either wall mounted, s:eiling mounted or otherwise.
The secondary heat exchangers 36 of the respective remolte units 3a to 3d are independently connected ~o the main heat exchanger 11 of the central unit 2 by four independent c;rculat;ng c;rcuits

4. Circulating pumps 23a to 23d driven by a pump motor 24a ~o 24d are proYided in the flow lines 21a to 21d of the re~spective circulating circuit 4 adjacent the ma;n heat exchanger :11 for independently circula~ing the heat transfer medium to tlhe remote units 3a to 3d. The pump motors 24a to 24d ~re controlled by the m;croprocessor 26 ~hrough pump controllers 30a to 30d, respectively, for delivering heat transfer medium ~hrough the circulating circui~s 4 to the re~s~te units 3a to 3d indlependently of each other. A flow manifold 56 and a return manifold 57 connect the circulating circuits 4 directly ~o the main heat exchanger 11 of the cen~ral unit 2~ Return temperature sensors 32a to 32d and flow temperature sensors 33a to 33d for monitoring the return and ~low temperatures of the heat ~ransfer mediu~ are provided in the return lines 22a to 22d and the flow lines 21a to 21d, respecti~ely.

Flow meters 5Ba to 58d are prov;ded ;n the respective circulating 2~ circuits 4 for determining the quantlty of heat t~ansfer medium flowing in each circulating circuit 4 for determinin~ in eombination with the return and flow temperature sensors 32a to 32d and 33a t:o 33d, the quantity of heat delivered to tlhe secondary heat exchanger 36 of each remote unit 3.

The microprocessor 26 of the central uni~ 2 operates under the control of a computer programme and sub-routines subs~antially similar to those described with reference Figs~ 4 to 6~ The microprocessors 40 of the remote units 3 operate under respective computer programmes substantially similar to that described with WO 93/U3311 PCr/IEs2J00004 38 ~ ~

referenee to Fig. 3. Should the m;croprocessor 40 of any of the remote units 3 determine that the ~;empera~ure sensed by the air temperature sensor 41 of that remote unit 3 is greater than or equal to 1C abo~/e the set point temperature of the remote unit 3 or greater than or equal to 1C below the set poi~n~- temperature of the remote unit 3, the microprocessor 40 under the control of the computer programme operates the remote unit 3 as described with reference to Fig. 3. A request for heating or cooling as the case may be is delivered to the central unit 2 with the 10 identity of the remote unit 3. Should the request be for cooling and the central unit 2 is inaotive, ~hen the microprocessor 26 under the control of the computer programne of F;gs. 4 to 6 operates the central unit 2 as alrcady described with reference to Figs. 4 to 6. The refrigeration circui~ 8 is operated in a 15 ehilling mode. The circulating pump 23 of the circulating circuit 4 ccrresponding to the remote unit 3 reques~ing cooling is operated by the microprocessor 26 under the control of the computer programme and the sub routine 1, and delivers cooling to the remote unit 3. The microprocessor 26 reads the return and 20 flow temperature sensors 32 and 33, respectively, corresponding to the remote unit 3 requesting cooling and the eorresponding differentiating cireuit 34, and controls the eentral unit 2 and the cooling energy output of the refrigeration circuit 8 and the delivery rate of the circulating pump 23 corresponding to the 25 remote unit 3 in response $o the return temperature and the rate of change of return temperature of the heat transfer medium returning from that remote unit 3. Where a remote unit 3 requests heating from the central unit, and the central unit 2 is inactive, the central unit 2 operates under the control of the 30 computer prograllnne of Figs. 4 and 6 and delivers heating to the remote unit in response to the rehlrn temperature and the rate o~
chan~e oF the return temperature of the heat transfer med;um returning from that remote unit 3. Where two ~r more remote units 3 are being supplied w1th cooling or heating from the 35 central unit 2, the cooling or heating energy output of the refrigeration circuit 8 is matched to the sum of the demands of WC) 93/03311 PCr/IE92/00004 ~ i ~ ~ 9 3 8 the remote un;ts 3. Th;s is achieved by operating the compressor 12 of the refrigeration circuit 8 in response to the return temperature and the rate of ehange of the return temperature read from the return temperature sensor 32 and the different;ating circuit 34 which indieates the greatest demand,~ energy. The circulating pumps corresponding to the ~emote units 3 are controlled in response to the return temperature and the rate of change of the return temperature of the heat transfer medium being returned from the corresponding remote un;t 3.

~0 Should the central unit 2 on receiving a request for heating from the remote unit 3 be in the process o~ satisfying a request for cooling from another remote unit 3, the central unit 2 continues to supply the cooling request of that remote unit 3 unt;l the request 1or cooling has been satisfied. The central uni~ 2 then 1~ reverses the refr;geration cireuit 8 to operate ;n a heat pump mode and supplies heating to the remote unit 3 re~uestlng heating. However, in the intervening period before the central unit 2 comanences to supply heating to the remote unit 3 requesting heating if the return temperature monitored by ~he air temperature sensor 41 is determined to fall within the compar;sons of bloeks 323 and 326 of the ~low chart of Fig. 2, the electrical.ly powered heater 37 i5 operated in aecordanee with ~lock 325 and 327. In the event that the central unit 2 is delivering heating to the remote unit 3 and the comparisons of blocks 323 and 326 are found to apply the heater 37 of the remote unit 3 is also operated under the control of block 325 and 327.

If the central unit 2 is operating in a heat pump mode delivering heat to a remote unit 3 and anothe~ remote unit 3 demands~ -cooling, the computer programme controlling the microprocessor 26 of the central unit 2 ~oes to block 405 and in turn reYerses the refrigeration circuit 8 to operate in a chilling ~ode and commences to proceed to block 408 onwards. In which case, if the demand for heating by the remote unit 3 which had been receiving heating from the ccntral unit 2 has not been satisfied, and the WO 93/03311 lPCME92/00004 ,t~ 8 compar;sons of blooks 323 and 326 of the computer progran~ne of ~ig. 3 apply, then the electrically powered Iheater 37 of that remote unit 3 is operated under the control of blocks 325 or 3270 In use, the occupants of the respee~ive zones 5~ nter the

5 desired set point temperature at which the ambient air in the zones is to be maintained into the microprocessors 40 of the respective remote units 3 thrsugh the appropriate keypads 45.
This operation is similar to tha~ described witlh relFerence to the appara~us of Figs. 1 to 6. The remote units 3 then operate under 10 the oontrol of l~he computer progranmes described with reference to Fig. 3, and the central unit 2 operates under the control of the colnpllter progran~ne and sub-routines described with reference to ~igs. 4 to 6~ Where a request for cooling by a remote unit 3 is made to the central unit 2, the central unit 2 is operated to 15 supply eooling through the heat tra~nsfer mediunl t~ the remote unit 3 as already described. Where a request for heating is made by remote unit 3, the demand for heating is supplied by the central unit 2 provided that the central unit is not already supplying eooling to another remote unit 3. In which case, the 20 eentral U11it eontinues tn supply cool;ng to that remote unit 3 until its demand has been satisfied. The eentral unit 2 then, should the demand still remain from the remote unit 3 for heating, reverses to operate in a heat pump mode and supplie~
heating to the remote unit 3 requiring heating. Where heating is not beirg supplied to a remote un;t 3 demanding heating by the central unit 2, the microprocessor 40 under the control of the computer programme operates the electrically powered heater 37 of that remote unit 3 until the demand for heatins has been satisfiedl or the cen~ral unit 2 can supply sufficient heating that the electrically powered heater 37 ;s no longer required.
At which stage the heater 37 is deactivated by the microprocessor 40 of the remote unit 3 under the control of the computer programme.

It is envisaged that Yarious other controls may be incorporated WO 93/03311 P~/lE92/oolDo4 2 ~ 3 8 in the computer programmes of the microprocessors 26 and 40O For example, it is envisaged that a sub-routine may be prov1ded for permitting disabling of some or more of the remote un;ts and ;n certain cases the central unit during predetermined periods of a twenty-four cycle, particularly, for example, a~ ght from midnight to six a.m~ It is also envisaged that maximum values of set point temperatures which may be selected by occupiers in remote units may be controlled from the central un;t, for example, it is ~nvisa~ed that the maximum set point temperature which may be selected during the morning might be set a maximum limit over which an occupier could not exceed and such maximum l;mit ~ay be lowen during the morning of a twenty-four hour period than in the evening, when, in general, a higher ambient temperature would be required, particularly, in a residential zone.

It is also envisaged that a number of remo~e units may be connected to one remote unit. In such cases, it is envisaged that one of the remote units would act as a master remote unit and the others would act as slave remote units under the control of the master remote unit. In which case, the master and its corresponding slave remote units would be connected to the :~
central unit through a single circulat;ng cirouit which would -:
include a s;ngle circulating pump. Signals reguesting heating or cooling from the central !unit would be trans~itted from the master remote un;t to the central unit.

While the multi-zone heat control apparatus of Figs. 7 and 8 has been described for controlling the temperature of four zones of a building, it will readily be apparent that the apparatus may be used for controll;ng the temperature of any number of zones from two upwards. In which case, a remote unit would be provided for each zone and the remote units for each zone would be connected independently of each other to the central unit 2. :`

it is envisaged that separate fans may be provided for WO 93/03311 PCr/lE9~/0~004 ". .. ~ , 3 ~;

transfe~ring heat ~rom the secondary heat exchanger and the electrically powered heater of each remote un;t. Needless to say, any suitable booster heat delivery means besides an electrically powered heater may be provided.
, --_ S While the secondary heat exchangers have been described as coil heat exchangers, any other suitable heat exchangers may be prov;ded. Needless to say, wh;le the main heat exchan~er has been described as being a plate heat exchanger any other suitable heat exehan~er may be used. It will also be appreciated that any other suitable heat exchanger may be used besides a fan assisted coil heat exchan~er for the master heat exchanger.

While the refrigerant med;um has been described as being freon, any other ~uitable refrigerant medium may be used.

Additionally, while i~ is preferable that the heat transfer lS ~edium should be water, any other suitable heat transfer mediums may be used. In practice, i~ is envis~ged that the h~at transfer medium w;ll be ~ liquid medium.

While the apparatus of Figs. 1 to 6 has been described for both heating and cooling~ in certain cases, it is envisaged that the apparatus may bc provided for space eooling only. In whieh case, the refrigeration circuit would not be reversible.
Alternatively, it is envisaged that ~he refrigeratlcn circuit of the appara~us of Figs. 1 to 5 may be constructed to aet as a heat pump only, in which case, the apparatus of FigsO 1 to 6 w~uld only provide space heating.

It is also envisaged that the temperature control apparatus of Fig. 1 could include a number of remote uni~s which would be ~:
supplied by the same central unit either in para~lel or in serles with each other.

30 While the di~ferentiating means for determining the rate o~ :

w o 93/0331l PC~/IE92/00004 chan!ye of temperature of the heat transfer medium returning to the icentral uni~ has been descr;bed as being provided by a diff~erentiating circuit, any other suitable differentiating means may be provided. Indeed, in many cases, it is envisaged that the 5 differentiating means m~y be prov;ded in the mi~processor 26 and could be implem~nted by a suitable computer programmlD.

While the co~munieatin~ means for cammunicating the microprocessors 40 of the remote units 3 wi~h ~he microprocessor 26 of the central unit 2 have been d~scribed as being cables, any other su;tahle communicating means may be used, for example, rad;io transmission communication means or the like.

While specif;c ran~es of return temperatures of the heat transfer medium, and specific predetermined values of the ra~e of change of lthe return temperature of the heat transfer medium have been desoribed at which the output of the refrigeration cireuit and the circulating pump are changed, it will be readily apparent to tho~se skilled in the art, that other ran~es of return temperature or temperature differences between return and flow tempe!ratures and predetermined rates of change of return temperature may be use,d. Indeedl in certain cases, it is envisaged that the energy outlput of the refrigeration circuit and the delivery ra~e of the eirculating pump may be responsive to relatively small increments or decrements of change of return temperature or temperature difference and to relatively small increments or decrements of rate of change of return temperature.

Claims

CLAIMS:

1. A central unit (2) for supplying a heat transfer medium to at least one remote unit (3) of temperature control apparatus (1,50) for transferring heat between the central unit (1) and the remote unit (3), the central unit (1) being of the type comprising a refrigeration circuit (8) having a refrigerant medium therein, the refrigeration circuit (8) comprising a master heat exchanger (10) for exchanging heat with the refrigerant medium, and a main heat exchanger (11) for exchanging heat between the refrigerant medium and the heat transfer medium, a compressor means (12) for compressing the refrigerant medium, and an expansion means (18) for expanding the refrigerant medium, characterised in that, return temperature monitoring means (32) for monitoring the return temperature of the heat transfer medium returning to the main heat exchanger (11) is provided, differentiating means (34) for determining the rate of change of the return temperature of the heat transfer medium with respect to time is provided, and first control means (25) responsive to the differentiating means (34) is provided for controlling the energy output of the refrigeration circuit (8) in response to the rate of change of the return temperature of the heat transfer medium with respect to time.

2. A central unit as claimed in Claim 1 characterised in that the first control means (25) varies the energy output of the refrigeration circuit (8) in response to a change in the rate of change of the return temperature of the heat transfer medium with respects to time.

3. A central unit as claimed in Claim 1 or 2 characterised in that the first control means (25) is responsive to the rate of change of the return temperature of the heat transfer medium with respect to time moving from one predetermined range of rates of change of return temperature to another range.

4. A central unit as claimed in any preceding claim characterised in that the first control means (25) is responsive to the rate of change of the return temperature of the heat transfer medium with respect to time reaching a predetermined value.

5. A control unit as claimed in any preceding claim characterised in that the first control means (25) comprises compressor control means (29) for controlling the compressor means (12) for varying the energy output of the refrigeration circuit (8).

6. A central unit as claimed in Claim 5 characterised in that the compressor control means (29) comprises means for controlling the mark/space ratio of a power supply (28) being delivered to the compressor means (12).

7. A central unit as claimed in Claim 6 characterised in that the compressor control means (29) varies the mark/space ratio of the power supply to the compressor means (12) inversely to the rate of change of the return temperature with respect to time.

8. A central unit as claimed in any preceding claim characterised in that a pump means (23) for circulating the heat transfer medium through the main heat exchanger (11) is provided, the first control means (25) comprising pump control means (30) for controlling the delivery of the pump means (23), the pump control means (30) being responsive to the differentiating means for controlling the delivery of the pump means (23) in response to the rate of change of the return temperature of the heat transfer medium to the main heat exchanger (11) with respect to time.

9. A central unit as claimed in Claim 8 characterised in that the pump control means (30) varies the delivery of the pump means (23) inversely to the rate of change of the return temperature with respect to time.

10. A central unit as claimed in any preceding claim characterised in that the first control means (25) is responsive to the return temperature of the heat transfer medium.

11. A central unit as claimed in Claim 10 characterised in that the first control means (25) is responsive to the return temperature of the heat transfer medium moving from one predetermined range of return temperatures to another range.

12. A central unit as claimed in Claim 10 or 11 when dependent on Claim 6, characterised in that the compressor control means (29) varies the mark/space ratio of the power supply to the compressor means (12) proportionately to the temperature difference between the return temperature of the heat transfer medium and the flow temperature of the heat transfer medium flowing from the main heat exchanger (11).

13. A central unit as claimed in Claim 10 to 12 when dependent on Claim 8 characterised in that the pump control means (30) varies the delivery of the pump means (23) proportionately to the difference between the return temperature of the heat transfer medium and the flow temperature of the heat transfer medium flowing from the main heat exchanger (11).

14. A central unit as claimed in any preceding claim characterised in that the refrigeration circuit (8) is reversible and is operable in a chilling mode and a heat pump mode, and means (18) for reversing operation of the refrigeration circuit between the two modes is provided.

15. A central unit as claimed in any preceding claim characterised in that the compressor means (12) is a scroll compressor.

16. A central unit as claimed in any preceding claim characterised in that the heat transfer medium is water.

17. Temperature control apparatus (1,50) comprising a central unit (2) as claimed in any of Claims 1 to 16 and a remote unit (3), the remote unit (3) being connected to the central unit (2) by a circulating circuit (4) for circulating a heat transfer medium between the central unit (2) and the remote unit (3).

18. Temperature control apparatus as claimed in Claim 17 characterized in that the remote unit comprises a secondary heat exchanger (36) for exchanging heat with the heat transfer medium, a booster heat delivery means (37), and a heat transfer means (38)for transferring heat to or from the secondary heat exchanger (36) and the booster heat delivery means (37), air temperature monitoring means (41) for monitoring the return temperature of air to the remote unit, and second control means (39) responsive to the air temperature monitoring means (41) for controlling the heat transfer means and for delivering a signal to the first control means (25) for activating the central unit (2).

19. Multi-zone temperature control apparatus (50) comprising a plurality of remote units (3), one remote unit (3) being provided for each zone (51), a central unit (2) as claimed in any of Claims 1 to 16 for supplying a heat transfer medium to the remote units (3) for transferring heat between the central unit (2) and the respective remote units (3) for controlling temperature of the zones (51), each remote unit (3) comprising a secondary heat exchanger (36) for exchanging heat with the heat transfer medium, a heat transfer means (38) for transferring heat between the secondary heat exchanger (36) and the zone, air temperature monitoring means (41) for monitoring the temperature of air in the zone, and second control means (39) responsive to the air temperature monitoring means (41) for controlling the heat transfer means (38) and for delivering a signal to the first control means (25) for activating the central unit (2) in response to a change in temperature of the air, the apparatus (50) further comprising a plurality of circulating circuits (4) for communicating the secondary heat exchangers (36) of respective remote units (3) with the main heat exchanger (11) of the central unit (2) for circulating the heat transfer medium between the main heat exchanger (11) and the respective secondary heat exchangers (36), characterised in that, ciculating means (23) are being provided in respective circulating circuits (4) for circulating the heat transfer medium.

20. Multi-zone temperature control apparatus as claimed in Claim 19 characterised in that each circulating means (23) is responsive to the first control means (25).

21. Multi-zone temperature control apparatus as claimed in Claim 19 or 20 characterised in that the heat transfer medium is water.

22. Multi-zone temperature control apparatus as claimed in any of Claims 19 to 21 characterised in that the circulating circuits (4) are connected to the main heat exchanger (11) independently of each other.

23. Multi-zone temperature control apparatus as claimed in any of Claims 19 to 22 characterised in that each remote unit comprises a booster heat delivery means (37), the heat transfer means (38) co-operating with the booster heat delivery means (37) for transferring heat between the booster heat delivery means (37) and the zone (51).

24. Multi-zone temperature control apparatus as claimed in Claim 23 characterised in that the booster heat delivery means (37) is responsive to the second control means (39).

25. Multi-zone temperature control apparatus as claimed in Claim 23 or 24 characterised in that each booster heat delivery means (37) comprises a heat source.

26. Multi-zone temperature control apparatus as claimed in Claim 25 characterised in that each booster heat delivery means (37) is provided by an electrically powered heat source.

27. Multi-zone temperature control apparatus as claimed in any of Claims 19 to 26 characterised in that each secondary heat exchanger (36) is provided by a coil heat exchange.

280 Multi-zone temperature control apparatus as claimed in any of Claims 19 to 27 characterised in that each heat transfer means (38) comprises a fan.

29. Multi-zone temperature control apparatus as claimed in Claim 28 characterised in that the fan (38) is electrically powered.

30. Multi-zone temperature control apparatus as claimed in any of Claims 19 to 29 characterised in that each circulating means (23) comprises a circulating pump.

31. Multi-zone temperature control apparatus as claimed in Claim 30 characterised in that each circulating pump (23) is an electrically powered variable speed circulating pump.

32. Multi-zone temperature control apparatus as claimed in any of Claims 19 to 31 characterised in that the air temperature monitoring means (41) are mounted in the respective remote units (3) for monitoring the return air temperature of air returning to the respective remote units (3).

33. Multi-zone temperature control apparatus as claimed in any of Claims 19 to 32 characterised in that the central unit (2) comprises a refrigeration circuit (8) having a refrigerant medium therein and comprising the main heat exchanger (11) for exchanging heat between the refrigerant medium and the heat transfer medium, a master heat exchanger (10) for exchanging heat with the refrigerant meduum, a compressor means (12) for compressing the refrigerant meduim and an expansion means (14) for expanding the refrigerant medium, the refrigeration circuit (8) being responsive to the first control means (25).

34. Multi-zone temperature control apparatus as claimed in Claim 33 characterised in that the refrigeration circuit (8) is reversible, and means (18) for reversing the refrigeration circuit is provided.

35. Multi-zone temperature control apparatus as claimed in any of Claims 19 to 34 characterised in that flow temperature monitoring means (33) for monitoring the flow temperature of the heat transfer medium from the main heat exchanger (11) is provided in each circulating circuit (4).

36. Multi-zone temperature control apparatus as claimed in Claim 35 characterised in that flow measuring means (58) is provided in each circulating circuit (4), the flow temperature monitoring means (33) and flow measuring means (58) being connected to the first control means (25) for enabling computation of the energy delivered to the secondary heat exchangers (36) of the respective remote units (3).

37. A method for controlling the energy output of a central unit (2) of temperature control apparatus (1,50), wherein the central unit (2) is of the type which supplies a heat transfer medium to at least one remote unit (3) of the temperature control apparatus (1,50) for transferring heat between the central unit (2) and the remote unit (3), and the central unit (2) comprises a refrigeration circuit (8) having a refrigerant medium therein, the refrigeration circuit (8) comprising a master heat exchanger (10) for exchanging heat with the refrigerant medium, and a main heat exchanger (11) for exchanging heat between the refrigerant medium and the heat transfer medium, a compressor means (12) for compressing the refrigerant medium, and an expansion means (14) for expanding the refrigerant medium, the method being characterised in that, the method comprises the steps of determining the rate of change of the return temperature of the heat transfer medium returning to the main heat exchanger (11) with respect to time, and controlling the energy output of the refrigeration circuit (8) in response to the rate of change of the return temperature of the heat transfer medium.

38. A method as claimed in Claim 37 characterised in that the method comprises the step of varying the energy output of the refrigeration circuit (8) in response to a change in the rate of change of the return temperature of the heat transfer medium with respect to time.

39. A method as claimed in Claim 37 or 38 characterised in that the energy output of the refrigeration circuit (8) is varied in response to the rate of change of the return temperature of the heat transfer medium with respect to time moving from one predetermined range of rates of change of return temperature to another range.

40. A method as claimed in any of Claims 37 to 39 characterised in that the energy output of the refrigeration circuit is varied in response to the rate of change of the return temperature of the heat transfer medium with respect to time reaching a predetermined value.

41. A method as claimed in any of Claims 37 to 40 characterised in that the method comprises the step of controlling the compressor means (12) for varying the energy output of the refrigeration circuit (8).

42. A method as claimed in Claim 41 characterised in that the method comprises the step of controlling the mark/space ratio of a power supply being delivered to the compressor means (12).

43. A method as claimed in Claim 42 characterised in that the method comprises the step of varying the mark/space ratio of the power supply to the compressor means (12) inversely to the rate of change of the return temperature with respect to time.

44. A method as claimed in any of Claims 37 to 43 characterised in that the method comprises the step of varying the energy output of the refrigeration circuit (8) in response to a change in the return temperature of the heat transfer medium.

45. A method as claimed in Claim 44 characterised in that the method comprises the step of varying the energy output of the refrigeration circuit (8) in response to the return temperature of the heat transfer medium moving from one predetermined range of return temperature to another range.

46. A method as claimed in any of Claims 42 to 45 characterised in that the method comprises the step of varying the mark/space ratio of the power supply to the compressor means (12) proportionately to the temperature difference between the return temperature of the heat transfer medium and the flow temperature of the heat transfer medium flowing from the main heat exchanger (11).

47. A method as claimed in any of Claims 37 to 46 characterised in that the method further comprises the steps of varying the rate of circulation of the heat transfer medium through the main heat exchanger (11) in response to the rate of change of the return temperature of the heat transfer medium to the main heat exchanger (11) with respect to time.