GB2480009A

GB2480009A - Control unit for use with space heating and cooling systems such as HVAC

Info

Publication number: GB2480009A
Application number: GB1107158A
Authority: GB
Inventors: David Stapleton
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-04-29
Filing date: 2011-04-28
Publication date: 2011-11-02
Also published as: GB201007126D0; GB2479910A; GB201107158D0

Abstract

The control unit 104 comprises an input interface 104-1, 104-2 and output interface 104-3. In use, the input interface receives a first data signal `Cp' from a portable sensor 100 and a second data signal `CT' from a fixed sensor 106. The output interface transmits a control signal `CHU' based upon either of the first or second data signals. The control unit further comprises a means 105 for selectively determining the control signal in preference of the first signal over the second signal. The fixed sensor may be a thermostat controlling a central heating unit 108. The portable sensor may include a temperature sensor 100-2, the portable sensor measuring the temperature in a room and wirelessly transmitting the temperature measurement in first data signal. The control unit may compare the temperature sensed by the portable sensor with a desired temperature set by the thermostat and may send the control signal to the central heating unit based upon the comparison. The portable sensor may include an infrared or radio transmitter 100-3. The invention is advantageous when the portable sensor is located in a different room to the thermostat. A portable sensing unit and computer program are also claimed.

Description

Portable Central Heating Thermostat This invention relates to a HVAC (heating, ventilation and air-conditioning) control unit, a portable sensing unit adapted for use with the HVAC control unit and a HVAC control system comprising the control unit and the portable sensing unit.

This invention is especially relevant to the regulation of temperature by domestic central heating systems.

HVAC (heating, ventilation and air-conditioning) systems as commonly found in domestic buildings generally work according to similar principles. There is typically a single, fixed sensor at one place in the building which measures an environmental variable at that location and activates or de-activates the HVAC system or a local HVAC unit in order to maintain the variable at a pre-set value.

In the case of a domestic heating (or cooling) system, the sensor is a thermostat, typically wall-mounted in a particular room or a hallway of the building, and which activates or de-activates the heating (or cooling) system if the measured temperature deviates from a pre-set value in order to return the measured temperature to that value.

The problem with such a system is that by responding to the temperature measured at the location of the thermostat the HVAC unit may cause the temperature at other locations (without the thermostat) to differ significantly from the pre-set value. This can lead to a particular room becoming uncomfortable for its occupants. It can also lead to unnecessary operation of the HVAC unit which is wasteful of energy.

Typically, the room occupant will resort to manually adjusting the thermostat setting, moving between the particular room and the location of the thermostat and changing the pre-set temperature at the thermostat by trial and error until a suitable temperature is reached in the particular room. However, this is both time consuming and imprecise, as well as being impractical for the elderly, infirm and others with limited mobility.

A possible solution is to have multiple thermostats, preferably one in each room, with the various heating requirements being co-ordinated via a central processor.

However, this is a costly and potentially highly disruptive solution, not least because the modification of the entire (or large parts of the) household heating system and installation of the central processor would likely need to be carried out by a trained professional.

There is therefore a need for a simple and inexpensive way to allow for the regulation of a domestic HVAC system at the level of individual rooms.

Various heating control systems have been proposed previously, including the following: NL1013038 (Sanders) discloses a thermostat device for domestic central heating systems. The ambient temperature in a room is measured and fed into a microprocessor, then integrated using a software program in order to give an accurate reading, before being displayed via an LED display. A push button in the device is used to move the thermostat control temperature up and down the LED display scale.

DE19520143 (Bohn) discloses a temperature regulation system for a central heating system. The heated water from a boiler is supplied through a feed pipe to a radiator and is then returned to the boiler. Two temperature sensors monitor feed and return pipe temperatures and the signals from the sensors are processed to provide values that are multiplied by a variable that is a function of the regulator output. The regulator then compares the modified signals with the reference to generate the error signal applied to adjust the thermostat valve.

DE4221094 (Jakob) discloses a room temperature control system that uses signals generated by a remote controller connected to the regulator of the hot water boiler. The remote controller has a transmitter that outputs program data over the wireless link to signal receivers mounted on the thermostat valves of radiators located in different rooms. Temperature sensors on feed and return lines provide signals for the on-off control of the boiler. Changes in operating point can be provided using the remote controller. The apparatus thereby allows individual room temperature control using remote controllers.

However, none of these heating control systems appear to provide an adequate solution to the problems described above. This invention aims to provide such a solution and to address at least some of the above-mentioned problems.

According to an aspect of the present invention there is provided a control unit for a HVAC (heating, ventilation and air-conditioning) system, the control unit comprising: an input interface for receiving a data signal from a sensor; an output interface for transmitting a control signal to a HVAC unit; and means for selectively determining the output control signal in dependence on an input data signal received from a portable sensor in preference to an input data signal received from a fixed sensor.

Provision of such a control unit may allow for ready modification, for example by retro-fitting, of an existing HVAC control system comprising a fixed sensing unit to facilitate the selective preferential use of data from a portable sensing unit, thereby improving control of the HVAC unit.

According to another aspect of the invention there is provided a portable sensing unit comprising: means for generating a data signal; and means for transmitting the data signal; wherein the portable sensing unit is adapted for use in combination with the HVAC control unit.

According to a further aspect of the invention there is provided a HVAC control system, comprising: a control unit and a portable sensing unit.

Preferably, the control unit is operable i) in a first mode, wherein the control signal is determined from a data signal received from a fixed sensor; and ii) in a second mode, wherein the control signal is determined from a data signal received from a portable sensor.

Preferably the control unit is adapted to switch between the first mode and the second mode in dependence on a data signal received from a portable sensor.

Preferably the control unit further comprises: means for determining a value encoded in the data signal received from the portable sensor; means for comparing the encoded value with a preset value stored by the control unit; and wherein the control unit is adapted to switch between the first mode and the second mode in dependence on the result of the comparison.

Preferably the preset value determines a range of possible values.

Preferably the preset value determines an environmental parameter.

Preferably the preset value determines a temperature.

Preferably the control signal is determined from the result of the comparison.

Preferably the control signal is one of an activation signal or a deactivation signal.

Preferably the control unit further comprises means for manually switching the control unit between first and second modes.

Preferably the input interface is adapted to receive data signals wirelessly from a

portable sensor.

Preferably the input interface is adapted to receive data signals from a portable sensor comprising at least one of: infrared, radio, Bluetooth and/or optical signals.

Preferably the control unit is adapted to receive input signals from a plurality of portable sensing units.

Preferably the control unit is adapted to determine the control signal in dependence on the value encoded in a selected one of the plurality of the

portable sensors.

Preferably the control unit is adapted to determine the selected portable sensor in accordance with the most extreme of the encoded values encoded in the data signals received from the portable sensors.

Preferably the control unit is adapted to determine the selected portable sensor in accordance with the most recently activated of the plurality of the portable sensors.

Preferably the control unit is adapted to determine the selected portable sensor according to the proximity of at least one of the plurality of portable sensors to the control unit.

Preferably the control unit is adapted to determine the proximity of a portable sensor according to the signal strength received at the input interface.

Preferably the control unit is adapted to determine the selected portable sensor according to signal propagation time delay.

Preferably the control unit is adapted to determine the selected portable sensor according to a hierarchical list.

Preferably the control unit is adapted to interoperate with at least one other control unit.

Preferably the control unit is adapted to determine whether it or the at least one other control unit is the nearer to a portable sensor.

Preferably the control unit is adapted to be retro-fitted to an existing HVAC system and comprises means for receiving at the input interface an input signal from an existing fixed sensor and means for transmitting via the output interlace a control signal to an existing HVAC unit.

Preferably the existing fixed sensor is an existing wall-mounted thermostat.

According to another aspect of the invention, there is provided a portable sensing unit comprising: means for generating a data signal; and means for transmitting the data signal; wherein the portable sensing unit is adapted for use as the portable sensor as herein described.

Preferably the portable sensing unit further comprising means for measuring an environmental parameter.

Preferably the environmental parameter is temperature.

Preferably the means for generating a data signal is adapted to generate the data signal in dependence on the environmental parameter.

Preferably the means for generating a data signal is adapted to encode a value determined from the environmental parameter in the generated data signal.

The portable sensing unit preferably further comprises means for manually transmitting a data signal.

Preferably the manually transmitted data signal comprises at least one of: an activation I deactivation signal; a signal requesting a desired environmental parameter; a signal requesting an increase I decrease of a desired environmental parameter.

The portable sensing unit preferably further comprises an electromagnetic signal transmitter adapted to transmit the data signal from the portable sensing unit.

According to a further aspect of the invention, there is provided a HVAC control system, comprising: a control unit as herein described; and a portable sensing unit as herein described.

Further features of the invention are characterised by the dependent claims.

The fixed sensing unit may also be referred to as a (fixed) sensor or thermostat, a wall-mounted or walled thermostat; the portable sensing unit may also be referred to by various terms such as a portable sensor or thermostat, a portable control unit, a portable sensing/control unit, a remote thermostat or a remote unit.

Features described in terms of a heating system comprising heating unit, heating control unit and one or more thermostats may also be understood as referring more generally to a HVAC system with appropriate control unit and sensors.

Further aspects of the invention include: * apparatus for efficiently controlling a heating system in a building comprising a portable unit and a receiving unit * a portable unit comprising a thermostat, transmitter and means for communicating with the receiving unit * a receiving unit comprising a receiver and means of controlling the heating system through the existing thermostat * a portable unit which has an integrated thermometer, which senses the temperature and sends a signal, based on this and a target temperature, to receiving unit * a receiving unit which can be retro-fitted to an existing thermostat and acts to bypass the thermometer and temperature settings of the thermostat, effectively replacing them with the settings from the portable unit * a heating system controlled by the above-mentioned portable unit, enabling the occupied room to be maintained at the desired temperature * apparatus for efficiently controlling a heating system in a building comprising: a wall mounted thermostat comprising a transmitter, a receiver, and means for controlling said heating system; and a portable thermostat comprising a transmitter, a receiver, and means for communicating with said walled thermostat * a portable thermostat adapted to be carried by means of at least one of: a handle, a belt hook, a clip, finger grips, a lanyard * a plurality of wall-mounted thermostats; wherein the portable thermostat communicates with the closest of said wall mounted thermostats * a plurality of portable thermostats, wherein multiple users can control said heating system.

* apparatus for efficiently controlling a heating system in a building, comprising: a wall mounted thermostat and a portable thermostat; the wall mounted thermostat comprising a transmitter, a receiver, and means for controlling said heating system; the portable thermostat comprising a transmitter, a receiver, and means for communicating with said walled thermostat.

* a single thermostat which a user could carry with them from room to room, which would adjust the temperature of the occupied room automatically as the user carries it around.

* a portable thermostat for a central heating system which is adapted to be carried from room to room by a user An advantage of the present invention is that the heating is turned off when the occupied room reaches the desired temperature, reducing the overall fuel consumption compared with a central heating system having a fixed thermostat in, for example, a hallway as is common. A further advantage is that the portable thermostat is adapted to be easy to carry around. A yet further advantage is that multiple users can carry portable thermostats to heat different rooms. A yet further advantage is that individual heating appliances can be controlled by different wall mounted thermostats.

The invention also provides a computer program and a computer program product for carrying out any of the methods described herein and / or for embodying any of the apparatus features described herein, and a computer readable medium having stored thereon a program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.

The invention also provides a signal embodying a computer program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein, a method of transmitting such a signal, and a computer product having an operating system which supports a computer program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.

The invention extends to methods and/or apparatus substantially as herein described with reference to the accompanying drawings.

Any apparatus feature as described herein may also be provided as a method feature, and vice versa. As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure.

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa.

Furthermore, features implemented in hardware may be implemented in software, and vice versa. Any reference to software and hardware features herein should be construed accordingly.

These and other aspects of the present invention will become apparent from the following exemplary embodiments that are described with reference to the following figures in which: Figure 1 is a schematic overview of a heating control system; Figure 2 shows a variant of the heating control system of Figure 1 comprising a plurality of fixed heating control units and a single portable sensing/control unit; Figure 3 shows a further variant of the heating system comprising a plurality of portable sensing/control units; Figure 4 is a further schematic overview of the heating control system; Figure 5 shows a multi-zone system based on the system of Figure 4; Figure 6 is a flow diagram of example control sequences for the heating control system; Figure 7 shows an example of the portable sensing / control unit or thermostat; and Figure 8 shows an example of the heating control unit or wall-mounted thermostat.

Figure 1 is a schematic overview of a heating control system 1 located in a room 2 of a building. Central heating unit 108 -generally a HVAC (or heating / ventilation / air-conditioning) unit -provides heating (or, in alternatives, ventilation and/or air-conditioning) to the room 2 or to some other area of the building in which it is located by means of local heating units 109. Central heating unit 108 may, for example, be a boiler supplying heated water to radiators 109 or an air heater supplying warm air to vents 109. The temperature to which the central heating unit 108 heats the room 2 is usually determined by a user setting a desired temperature at a fixed thermostat 106, which monitors the temperature of the room 2 and controls (for example by activating and de-activating) the central heating unit 108 accordingly, thereby correspondingly affecting the temperature of the local heating units 109 to maintain the user-set desired temperature.

In some examples, central 108 and local 109 heating units may be considered as a single heating unit.

Portable sensing unit 100, when activated by a user, transmits a signal 102 to a heating control unit 104. The signal 102 acts as an override so that a user can control the system I using the portable unit 100. For example, when the local temperature (at the portable sensing unit 100) reaches a user-defined level (set at the portable sensing unit 100) the portable unit 100 transmits an override signal 102 to the heating control unit 104. Heating control unit 104 then transmits a control signal 112 to the central heating unit 108 which via local heating units 109 thereby affects the heating throughout the building.

In some examples, portable sensing unit 100 enables the setting of a range -defined for example by a pair of upper/lower extreme range values or a maximum deviation from a desired value -and transmits signal 102 to a heating control unit 104 when the local temperature (at the portable sensing unit 100) falls outside the allowed' range.

Heating control unit 104 may be a replacement for fixed thermostat 106 or alternatively work in combination with an existing fixed thermostat 106.

Typically, heating control unit 104 is designed to be retro-fitted to or alongside an existing thermostat 106, 50 that when activated by the portable control unit 100 it effectively allows for bypassing of the operation of the thermostat 106.

Alternatively, heating control unit 104 may be fitted directly onto the heating unit 108 or, in a further alternative, fixed thermostat 106 is positioned in-between the heating control unit 104 and the central heating unit 108.

When heating control unit 104 is inactive, it acts merely as a signal relay or conduit, the fixed thermostat 106 operating the system I as previously with the local temperature at the thermostat 106 determining the operation of the central heating unit 108.

The portable sensing unit 100 communicates with the heating control unit 104 wirelessly, for example using infrared, radio, Bluetooth or optical methods.

Alternatively, wired communication methods may be used. The signal is typically electromagnetic in nature, although other forms of signal may also be suitable.

The portable sensing unit 100 optionally has input controls, for example buttons, which the user can use to set a desired temperature (or other environmental parameter). Optionally, there may also be a display, for example an LCD screen, to display this user-set temperature and possibly other information such as the local temperature.

Heating control unit 104 may also comprise a transmitter and the portable sensing unit 100 a receiver so that the two-way communication between heating control unit 104 and portable sensing unit 100 is possible, and say the desired temperature can set on both devices 100, 104 simultaneously.

Heating control unit 104 may also have input controls, for example buttons, to allow for direct operation by a user and a display such as an LCD screen for feed back.

The system described allows for a building in which multiple local heat units 109 are controlled by a single fixed thermostat 106 to be upgraded by the retro-fitting of a single heating control unit 104. Subsequently, as the user carries portable sensing unit 100 from room 2 to another room 2-0 (from position X to Y, for example), portable sensing unit 100 remains in contact with heating control unit 104, first via signal 102 in room 2, then via signal 102-0 in room 2-0; control -12-signal 112 is therefore determined first by the temperature at X in room 2, then by the temperature at Y in room 2-0.

Figure 2 shows a variant of the above-described heating control system comprising a single portable sensing unit 100 and a plurality of fixed heating control units 104. The (fixed) heating control units 104 are located in different rooms 2 or regions of the building and may be connected to different heating units 110, which may for example be independent of each other rather than powered centrally. Fixed thermostats 106 can be set by a user to different temperatures independently, or alternatively, to a common temperature.

A single portable sensing unit 100 is taken by the user when moving about the building, for example as indicated from position A in room 2-1 to position B in room 2-2. If the user activates the portable sensing unit 100, it transmits a signal 102 (either 102-1 or 102-2) to the nearest heating control unit 104 (either 104-1 or 104-2, respectively) which then overrides the appropriate local fixed thermostat 106 (either 106-1 or 106-2, respectively) of the corresponding heating unit 110 (either 110-1 or 110-2, respectively) so that the local temperature is adjusted according to control signal 112-1, 112-2 to the user-defined level.

In some examples, the identity of the heating control unit 104 closest to the portable sensing unit 100 is determined by the heating control units 104 interoperating and determining between themselves which of them is receiving the strongest signal, which would correspond to being the closest to the portable sensing unit 100. This may be achieved, for example, by those heating control units 104 which receive a signal 102 from a portable sensing unit 100 transmitting a signal strength data 114 between each other to determine which is the closest.

Alternatively, the strength of signal 102 from the portable sensing unit 100 may be tailored so that it is most likely that only one heat control unit 104 will receive a signal 102 of sufficient strength at a time.

Another alternative is for the heat control unit 104 to repeat the received signal 102 to the portable sensing unit 100 which could then determine the closest heat control unit 104 by signal propagation time delay or other means. The portable sensing unit 100 could then send a specific signal to the determined nearest heat control unit 104.

Figure 3 shows a further variant of the heating system comprising a plurality of portable sensing units 100. Use of a plurality of portable units 100 allows for several independent users each to take a unit 100 with them as they move around the building.

In this example there is the possibility of having conflicting signals 102 being sent to the heating control unit 104.

One way of resolving such a conflict is to have the heating control unit 104 use the highest (most extreme) of the temperature settings of the received signals 102. For example, if a first user sets the desired room temperature to say 20°C, the heating unit 110 will be on until this room reaches 20°C. If a second user then sets a higher desired temperature, the heating unit 110 will continue to run until the room reaches this higher desired temperature (or until some other overriding signal is received). The heating control unit 104 will not switch off the heating unit until the highest of all the user-defined temperature levels on all portable control units 100 has been met.

Alternatively, in some examples the heating control unit 104 determines the controlling or master' portable control unit 100 according to a pre-set hierarchy or hierarchical list of portable control units 100 which of the conflicting signals to act upon. This hierarchy may be set by the portable control units 100.

In certain examples, the master' portable control unit 100 is the one most recently activated. A user can therefore assume control in a system with multiple portable control units 100 by simply resetting their own portable control unit 100.

In some examples, the signals 102 from the different portable sensing units 100 need to be distinguishable by the heating control unit 104. This could be done, for example, by each portable sensing unit 100 having a defined operating signal frequency or frequency range. The hierarchy could be set by changing the frequency of signal 102 for a particular portable sensing unit 100, or changing the -14-hierarchy of frequencies on the heating control unit 104, or both. This could be implemented automatically by software embedded in either the portable sensing unit 100 or in the heating control unit 104.

Alternative examples make use of combinations of these arrangements.

Figure 4 is a further schematic overview of the heating control system. In a typical prior art configuration, fixed thermostat 106 is in direct communication with the radiator 109 and/or with central heating unit 108 which supplies heat to radiator 109 in dependence on the temperature TT measured by thermostat 106.

Typically, thermostat 106 is set by the user to a desired temperature T0 and depending on whether the measured temperature TT at the thermostat 106 is higher or lower than T0 a control signal CR is sent to the radiator 109 and/or a control signal CHU is sent to the central heating unit 108 to request a corresponding decrease or increase in the amount of heat supplied.

Here, heating system I has a heating control unit 104 placed so as to selectively intercept the communication link between thermostat 106 and the radiator 109 and/or central heating unit 108 so that the control signals CR and/or CHU previously determined from signal CT provided by thermostat 106 can be determined instead from control signal Cp provided by portable sensing unit 100.

Heating control unit 104 comprises processor circuitry 105 which operates to switch the heating control unit 104 between a normal mode N' and an override or remote mode R' in dependence on a switching signal S received either from portable sensing unit 100 via radio interface 104-2 or from a user directly via by an input So at manual override button 104-4.

* In normal mode N', heating control unit 104 receives data such as a control signal CT from thermostat 106 at input 104-1 and forwards this via output interface 104-3 as control signal CR to radiator 109 and/or control signal CHU to heating unit 108.

* In remote mode R', when heating control unit 104 receives data such as control signal C from remote unit 100 over radio interface 104-2, this signal C is forwarded via output interface 104-3 as control signal CR to radiator 109 and/or control signal CHU to heating unit 108; signals CT received from thermostat 106 at input 104-1 are ignored.

Portable control unit 100 comprises circuitry 100-1 which is adapted to allow a user to set a desired temperature Treq, to read the temperature T from an integrated on-board thermometer 100-2 and -when the unit 100 is active -to relay a control signal Cp(Treq, Tp) by means of a radio signal into which the data is encoded and sent via radio interface 100-3 to radio interface 104-2 of heating control unit 104. A manual override 100-4 (such as a button) is provided to allow the unit 100 to be switched between active and inactive modes by an input So (such as a button press) provided by the user. An optional video display 100-5 may also be provided to display the user-set desired temperature Treq, temperature reading T and other pertinent information to the user.

The control signals CT, C, CR and CHU may take various forms, for example comprising encodings of direct temperature readings T and TT, temperature differences (TT -To) and (Tp -Treq) or other functions thereof such as a simple on/off signal for example when the temperature reading TT or TrGq exceeds the corresponding pre-set value lo or Treq.

Figure 5 shows a multi-zone system based on the system of Figure 4, comprising zones A and B each with corresponding fixed thermostats 106 controlling the heat supplied by heating unit 108 to radiators 109. As a user carrying portable control unit 100 passes from zone A to zone B, the portable control unit 100 communicates in turn first with heating control unit A when in zone A and subsequently with heating control unit B when in zone B, in each case sending to the corresponding heating control unit 104 a switching signal S and the corresponding control signals CPA or CPB which results in corresponding control signals C, CRB to respective radiators A, B 109 and/or respective control signals CHUA, CHUB to heating unit 108.

Figure 6 is a flow diagram of example control sequences for the heating control system, specifically for the portable sensing/control unit 100 and heating control unit 104. In the following, the usual convention of Y'I'N' to indicate Yes'I'No' outcomes at decision points applies.

The control sequence for the portable sensing/control unit 100 operates according to the following steps or stages: SI -Start.

* S2 -Default Treq &L1 (Ii T2) -When the portable unit 100 is first activated, default values of required temperature' (Treq) and allowed temperature range or deviation (Li) are set. Alternatively, the range may be set by temperature upper, lower limits T1 and T2, which may be defined by Li (as shown at 400).

* S3 -User input? -The user may change the default settings: o Y -If the user changes these values, the new values are set at S4, and the process continues; o N -Otherwise, the process continues * S5 -Measure T -The local temperature T is measured and may be stored by in local memory.

* S6 -T <T1? -The local temperature T is compared with the lowest allowed temperature, T1.

o Y -The local temperature T is too low; a signal C (e.g. a binary I') is sent at S7 to the heating control unit 104 so that the heating is turned ON'.

o N -Otherwise, the process continues.

* S8 -T >T2? -The local temperature T is compared with the highest allowed temperature, T2.

o Y -The local temperature T is too high; a signal Cp (e.g. a binary 0') is sent at S9 to the heating control unit 104 so that the heating is turned OFF'.

o N -Otherwise, the process continues.

* SlO -Off? -The portable sensing unit 100 may be turned off.

o Y -The process stops Sil and the portable sensing unit 100 is deactivated.

o N -Otherwise, the process continues at User input?' S3 above.

The control sequence for the heating control unit 104 is as follows: * S12-Start.

* S13 -Receive thermostat signal -The signal CT from the fixed thermostat 106 is received. Typically, this is a binary signal {0,1} corresponding to {OFF','ON'}.

* S14 -Receive remote signal? -The heating control unit 104 attempts to detect the signal C from the portable sensing/control unit 100.

o Y -If a signal is detected, the process continues to S16.

o N -If a signal is not detected, the output signal CR is set to the thermostat signal CT at S15. The system effectively operates in its original arrangement without the presence of the heating control unit 104 and portable sensing /control unit 100. The signal may not be detected as the portable unit 100 is switched off, or out of range.

The process then continues to S18 Send output signal to heating equipment'.

* S16 Is control unit in remote mode? -The control unit 104 may be operating so that the portable sensing unit 100 does not control the heating even if it is sending a signal.

o Y -If the control unit is in remote mode, the output signal CR is set to the remote signal C S17. The process then continues to S18 Send output signal to heating equipment'.

o N -If not, the output signal CR is set to the thermostat signal CT S15. The process then continues to S18 Send output signal to heating equipment'.

* S18 -Send output signal to heating equipment -The output signal CR is sent to the heating unit. This signal may be binary {0,1} corresponding to {OFF', ON'}. The process then continues to S19 Off?'.

* S19 Off? -The control unit 106 may be switched off o Y -The process stops S20 o N -The process returns to S14 Receive thermostat signal' to allow for potential changes to in the thermostat signal arising for example from changes in user settings or measured temperature.

Modifications and Alternatives In some alternatives, heat control unit 104 has a single input interface rather than separate input interfaces 104-1 for receiving signals from thermostat 106 and 104-2 for receiving signals from remote unit 100.

In some alternatives, a simpler portable control unit 100 without an integrated thermometer 100-02 may be used. Such a portable control unit 100 may enable a user to set a preferred temperature which overrides the pre-set temperature of thermostats 106 and effectively sets a local' temperature which accompanies the user moving between locations heated by heating system 1.

The various signals described may be more complex than simple binary on' or off'. The signals may contain information relating to, for example, the magnitude of the temperature inequality. This could enable the temperature to be adjusted more effectively, for example by modifying the power sent to a heating unit and/or the number of heating units activated or deactivated.

Switching signal S is optional in some examples; heating control unit 104 switches between normal mode N' and remote mode R' automatically according to control signal Op received from portable control unit 100 without requiring a switching signal S -for example, if temperature reading T differs from the pre-set temperature TrGq.

Many of the preceding examples describe a heating system; the skilled person will appreciate that many of the same principles of operation are equally suitable (with corresponding modifications) for use, for example, in cooling systems.

For example, where reference is made in the above description to turning the heating unit 108 ON' when the local temperature falls below that of the target temperature, a cooling system would instead replace heating unit 108 with a cooling unit and feature turning the unit ON' when the local temperature rose above that of the target temperature.

One way of modifying the process described above would be to simply swap the binary signal sent by the portable control unit 100 to the heating control unit 104 (shown by the optional NOT gate 402).

The system could also be used as a cooling and heating system simultaneously, or to regulate other climatic variables such as humidity with further minor modifications.

Additional examples

Figure 7 shows the portable thermostat 100. It is contained in a housing 1000 and preferably further comprises a screen 1040 and a handle 1060 as shown although these are not necessary components of the invention. The means for communicating with said walled thermostat 104 comprise controls 1020, which are shown as push buttons, but may also be dial, levers, touch pads, touch screens or other control means known in the art, external to the housing, and electronic switches, PCBs, or the like as known in the art internal to the housing.

The portable thermostat 100 is preferably adapted to be carried. It may comprise any or all of: a handle 1060 as shown, a belt hook, a clip, finger grips, a lanyard, or other means adapting the portable thermostat to be carried and/or worn as a user moves about a building.

The housing may comprise ABS, polypropylene or any suitable engineering polymer or other material and may take any shape which may be functional or decorative and preferably is as shown in the figure to co-ordinate with the wall mounted thermostat.

The screen is preferably an LCD screen since this is simple, inexpensive and suitable for this purpose but it may also be LED, CRT, plasma or any screen type known in the art.

The transmitter and receiver of the wall mounted and portable thermostats may be any suitable transmitter and receiver known in the art, for example infrared, radiowave, Bluetooth, optical or any transmitters and receivers, and are preferably wireless but may also use optical or electrical cables to communicate.

Figure 8 shows the wall mounted thermostat 104. It is contained in a housing 2000 which may comprise ABS, polypropylene or any suitable engineering polymer or other material and may take any shape which may be functional or -20 -decorative and preferably is as shown in the figure to co-ordinate with the portable thermostat 100.

The means for controlling said heating system preferably comprises push buttons 2020 as shown in the figure but may also comprise dials, levers, touch pads, touch screens or other control means known in the art, external to the housing, and electronic switches, PCBs, or the like as known in the art internally.

The wall mounted thermostat 104 preferably further comprises a screen 2040 which is preferably an LCD screen since this is simple, inexpensive and suitable for this purpose but it may also be LED, CRT, plasma or any screen type known in the art.

In a second additional embodiment, the apparatus comprises more than one wall mounted thermostat 100, for example, one in each room of a home. The wall mounted thermostats may each be connected to only one or only some radiators (or under-floor heating pipes or other heating means), for example the radiator or radiators in the same room as that thermostat. In this way, the portable thermostat 104 communicates with the closest wall mounted thermostat and thereby with the nearest radiator or other heating means only, bypassing the rest of the heating system. This ensures that only the radiators necessary to heat the occupied room to the required temperature are turned on, and not any other radiators, thus reducing fuel consumption.

In a third additional embodiment, the apparatus comprises more than one portable thermostat 104, wherein multiple users can control said heating system.

In this way, if a first user is in a first room with a first portable thermostat 104-1 and sets the temperature, for example, to 20°C, the heating system will be on until the first room reaches 20°C. At this point, the heating turns off. However if a second user with a second portable thermostat 104-2 is in a second room which is currently at a temperature of 18°C, the second portable thermostat will communicate with the wall mounted thermostat to turn the heating system on until the second room reaches 18°C -or alternatively 20°C if the first portable thermostat has priority. -21 -

It will be readily understood in this case that there is a possibility of the heating system receiving conflicting information from multiple thermostats. Such a system must therefore also comprise PCBs or the like in the thermostats, which are programmed to provide information as to which thermostat overrides in the case of a conflict. It may be possible that only one parent' thermostat comprises temperature setting means, while all other thermostats follow the temperature set by the parent and ensure that other occupied rooms are set to that temperature.

Alternatively the portable thermostats 104 may all comprise control means and thereby be able to set a desired temperature. The portable thermostats may be programmed to have priority orders. They may comprise a PCB which is programmed as known in the art to provide information to the wall mounted thermostat 100 as to which portable thermostat overrides the others in the case of a conflict.

Alternatively it may be possible, with multiple wall mounted thermostats connected individually to radiators as described above in the second additional embodiment, for each portable thermostat to comprise temperature setting means and for each room to be controlled individually. In this case the portable thermostats comprise a PCB which is programmed as known in the art to provide information to the wall mounted thermostat as to which portable thermostat overrides the others in the case that they are in the same room or in the region of the same wall mounted thermostat.

It will be readily understood that electronic components known in the art will enable many programmes and functions to be set in the wall mounted and portable thermostats of the present invention, not all of which are described herein, for example presetting of temperatures at different times, communication means between thermostats, etc, and that the invention is intended to include such programmes and functions.

It will be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

-22 -Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

Reference numerals appearing in the claims are by way of illustration only and shall have no limiting effect on the scope of the claims.

Claims

-23 -Claims 1. A control unit for a HVAC (heating, ventilation and air-conditioning) system, the control unit comprising: an input interface for receiving a data signal from a sensor; an output interface for transmitting a control signal to a HVAC unit; and means for selectively determining the control signal in dependence on an input data signal received from a portable sensor in preference to an input data signal received from a fixed sensor.
2. A control unit according to claim 1, wherein the control unit is operable i) in a first mode, wherein the control signal is determined from a data signal received from a fixed sensor; and ii) in a second mode, wherein the control signal is determined from a data signal received from a portable sensor.
3. A control unit according to claim 2, wherein the control unit is adapted to switch between the first mode and the second mode in dependence on a data signal received from a portable sensor.
4. A control unit according to claim 3, wherein the control unit further comprises: means for determining a value encoded in the data signal received from theportable sensor;means for comparing the encoded value with a preset value stored by the control unit; and wherein the control unit is adapted to switch between the first mode and the second mode in dependence on the result of the comparison.
5. A control unit according to claim 4, wherein the preset value determines a range of possible values.
6. A control unit according to claim 4 or 5, wherein the preset value determines an environmental parameter.

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7. A control unit according to claim 6, wherein the preset value determines a tern peratu re.
8. A control unit according to any of claims 4 to 7, wherein the control signal is determined from the result of the comparison.
9. A control unit according to any preceding claim, wherein the control signal is one of an activation signal or a deactivation signal.
1O.A control unit according to any of claims 2 to 9, further comprising means for manually switching the control unit between first and second modes.
11. A control unit according to any preceding claim, wherein the input interface is adapted to receive data signals wirelessly from a portable sensor.
12. A control unit according to claim 11, wherein the input interface is adapted to receive data signals from a portable sensor comprising at least one of: infrared, radio, Bluetooth and/or optical signals.
13. A control unit according to any preceding claim, wherein the control unit is adapted to receive input signals from a plurality of portable sensing units.
14.A control unit according to claim 13 when dependent on claim 4, wherein the control unit is adapted to determine the control signal in dependence on the value encoded in a selected one of the plurality of the portable sensors.
15. A control unit according to claim 14, wherein the control unit is adapted to determine the selected portable sensor in accordance with the most extreme of the encoded values encoded in the data signals received from the portable sensors.
16. A control unit according to claim 14, wherein the control unit is adapted to determine the selected portable sensor in accordance with the most recently activated of the plurality of the portable sensors.

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17. A control unit according to claim 14, wherein the control unit is adapted to determine the selected portable sensor according to the proximity of at least one of the plurality of portable sensors to the control unit.
18. A control unit according to claim 16, wherein the control unit is adapted to determine the proximity of a portable sensor according to the signal strength received at the input interface.
19.A control unit according to any of claims 14 to 17, wherein the control unit is adapted to determine the selected portable sensor according to signal propagation time delay.
20. A control unit according to claim 14, wherein the control unit is adapted to determine the selected portable sensor according to a hierarchical list.
21. A control unit according to any preceding claim, wherein the control unit is adapted to interoperate with at least one other control unit.
22.A control unit according to claim 21, wherein the control unit is adapted to determine whether it or the at least one other control unit is the nearer to aportable sensor.
23.A control unit according to any preceding claim, wherein the control unit is adapted to be retro-fitted to an existing HVAC system and comprises means for receiving at the input interface an input signal from an existing fixed sensor and means for transmitting via the output interface a control signal to an existing HVAC unit.
24. A control unit according to claim 23, wherein the existing fixed sensor is an existing wall-mounted thermostat.
25. A portable sensing unit comprising: means for generating a data signal; and means for transmitting the data signal; -26 -wherein the portable sensing unit is adapted for use as the portable sensor of any of claims I to 24.
26.A portable sensing unit according to claim 25, further comprising means for measuring an environmental parameter.
27.A portable sensing unit according to claim 26, wherein the environmental parameter is temperature.
28.A portable sensing unit according to claim 26 or 27, wherein the means for generating a data signal is adapted to generate the data signal in dependence on the environmental parameter.
29.A portable sensing unit according to claim 28, wherein the means for generating a data signal is adapted to encode a value determined from the environmental parameter in the generated data signal.
30. A portable sensing unit according to any of claims 25 to 29, further comprising means for manually transmitting a data signal.
31.A portable sensing unit according to claim 30, wherein the manually transmitted data signal comprises at least one of: an activation I deactivation signal; a signal requesting a desired environmental parameter; a signal requesting an increase I decrease of a desired environmental parameter.
32. A portable sensing unit according to any of claims 25 to 31, further comprising an electromagnetic signal transmitter adapted to transmit the data signal from the portable sensing unit.
33.A HVAC control system, comprising: a control unit according to any of claims I to 24; and a portable sensing unit according to any of claims 25 to 32.
34. A HVAC control unit as herein described and/or illustrated with reference to at least one of the accompanying drawings.

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35. A portable sensing unit as herein described and/or illustrated with reference to at least one of the accompanying drawings.
36. A computer program comprising code adapted to perform in software the functionality of any of the apparatus of any preceding claim.