GB2323938A - Control system for electrically actuated radiator valves in a central heating system - Google Patents

Abstract

A control system for electrically actuated radiator valves in a central heating system comprising a boiler and a plurality of water-filled radiators (figure 1). The control system comprises, on each radiator, an electrically actuated water flow control valve, and a control unit 20 to open and shut the valve as required, in dependance on a number of sensed parameters, one of which is temperature. In the embodiment, the other parameter is room occupancy, or the detection of motion in the room. The control unit 20 therefore incorporates a temperature sensing means 23 and an occupancy or motion sensor 26, which may be of the infra-red or ultrasound type. The control unit can also incorporate a conventional timer means 22. The unit can be constructed to plug into a conventional electrical socket. Further features are remote control of the device, and the ability to discriminate between motion of a person and presence of a person, and heat the room differently as a result. The construction of the actuator is also disclosed (figure 3).

Description

A CONTROL SYSTEM FOR HOT WATER CENTRAL HEATING EMPLOYING WATER HEATED RADIATORS It is known to fit thermostatic radiator valves to water heated radiators to restrict the flow of heated water therethrough when the ambient air around the valve reaches a temperature at which the thermostatic valve has been set to react thereto; and it is also known to control a central heating boiler by means of a programmable timer to energise the boiler at pre-programmed times for pre-programmed periods, and by means of a room thermostat which overrides the programmer to de-energise the boiler when the room reaches a temperature at which the thermostat has been set to respond. However, all these means of control, even when used in combination involve problems and compromise in trying to establish programming which is sufficiently generous in time and temperature to ensure that comfortable thermal conditions exist when persons are present, and is at the same time sufficiently parsimonious to minimise energy wastage and heating costs. Furthermore, the heating control offered by such thermostatic radiator valves is subject to perturbations which commonly arise in the vicinity of such radiators, e.g. the valves may be subject to a cooling bias by a cold downdraught from a window above the radiator and valve, or by a heating bias by heat radiated onto the valve by the radiator, causing aberrant or belated or premature, actuation of the valve. Thus, the valve actuations suffer from perturbations caused by thermal influences on the environment in the vicinity of the radiator to which the valve is fitted, e.g. the thermostatic actuator of the valve can receive variable amounts of radiated, conducted and convected heat from the radiator and pipework, and can be cooled by draughts and air flows e.g. created by an updraught past the radiator.

In many instances the valves require a strong spring to provide an opening bias sufficient to prevent the valve sticking closed, and this bias must be overcome by the thermostatic actuator before the valve can be closed or the valve opening can be reduced.

Invariably, these problems result in some rooms being overheated or underheated especially those rooms which have a pattern of occupancy which differs from that of the room in which the room thermostat is located.

Electrically powered individual room heaters e.g.

electric radiators, convector heaters, fires and fan heaters, can be controlled individually by means of builtin thermostats, and by timers which can be plugged into electrical wall sockets to provide timed control of the power to the heaters. However, using individual electrical heaters invariably involves problems of energy cost, and of course, the well known cost and other advantages of hot water central heating systems are lost.

Using modern technology it would be quite possible to design a multi-flow path hot water distribution system, e.g. using several selectively energisable pumps or distribution valves, controlled by a similar number of room thermostats so as to give selective heating of several individually selectable rooms, but the installation and equipment costs would probably be prohibitive or not cost effective for most customers.

The invention seeks to provide a low-cost solution to the foregoing problems.

According to the present invention there is provided a control system for a hot water central heating system employing water filled heat emitters, and a boiler to heat said water which boiler is energised via a suitable control such as a switch or programmable timer, the control system being characterised in that it comprises: a) at least one electrically actuated valve (i.e. a valve having an electrically controlled actuator) which can be fitted to one of the radiators to control the flow of hot water through the radiator, b) a programmable sensor or control unit to actuate (e.g. energise and de-energise the actuator of) the valve via an electrical cable according to a plurality of predetermined parameters, the first one of which is temperature.

The sensor is preferably of a form which can be plugged into a normal electrical supply socket.

The electrically actuated valve may be a solenoid valve or a motorised valve. However, motorised valves are expensive and complex, and solenoid controlled valves require relatively heavy currents to provide sufficient force to overcome the aforementioned bias.

What is needed is a low energy consumption inexpensive actuator for such a remotely controllable valve.

According to the prevent invention there is provided an actuator, for a water valve, in the form of a hollow body containing a bimetallic device and an electrical resistance heater assembly to heat the device, and comprising an abutment at one end of the bimetallic device so as to be engageable by a jumper or shaft of the water valve, and a hollow connector provided on the body to connect the body to the water valve, for actuation of the water valve by the abutment when the connector connects the body to the valve.

The body preferably encloses a bias spring to urge the bimetallic device towards a predetermined position.

The bimetallic device preferably includes a plurality of dished bimetallic discs which peripherally abut the heater assembly, and which are arranged to define therebetween a lenticular cavity in which a heating element of the heater assembly is located. The centre portion of one disc preferably carries the abutment and abuts a bias spring, and the centre portion of the other disc preferably abuts the body. The discs are preferably formed so as to diverge and increase their curvature when heated.

The control system and actuator of the invention are suitable for retro-fitting at very low labour costs and apparatus costs and permit individual and independent control of the heating of individual rooms.

The temperature sensing performed by the sensor enables most of the effects of the thermal aberrations usual to the vicinity of radiators to be avoided, and the cost of hard wiring additional room thermostats back to the boiler programmable timer to be avoided, because the sensor can be plugged into any suitable disposed wall socket, or into a wander lead so that it can operate in a chosen position in the room.

The electrically controlled radiator valve actuator, can be substituted for any other form of radiator valve quite simply and inexpensively, or may be provided on a valve which is then fitted to an open flow radiator (a radiator without a flow control valve) to update the heating system, or a conversion kit excluding the actuator can be provided to enable a manually or thermostatically controlled valve to be modified for electrical actuation.

Where a room has several radiators, a single programmable sensor may control several of the electrically controlled radiator valve actuators.

The, or one, further parameter is preferably timed in which the "on" periods (in which the valve is controlled by the sensed and set temperatures) are presettable according to the expected occupancy of the particular room concerned.

Additionally or alternatively, to time, the or a further parameter, may be the presence, absence or movement of a person (or any animal of significant size) in the room.

The programmable sensor is preferably unitary, but may have an input connection to receive at least one signal from a further sensor, e.g. the unit may comprise a programmer and a thermo-sensor and have an input to receive signals from an infra-red sensor disposed in a position to view a significant part of the room.

The infra-red sensor may respond to movement of a person, or presence of a person, or both thereof, and may be adapted to discriminate therebetween to give different signals, e.g. a low-heating requirement when a person is moving about in the room and a higher heat requirement signal when a person is sedentary in the room.

The unit is preferably programmable to permit a plurality of heating levels to be programmed, e.g. a low heat requirement level at times when persons are expected to be active in the room and a high heat requirement at times when persons are expected to be sedentary in the room.

Because the control system is intended to provide a relatively inexpensive means for economical upgrading of existing central heating systems, it may be purchased by householders whose houses have relatively few electrical supply socket outlets, of which the permanent occupancy of one thereof could be inconvenient. In order to avoid the further problem, the unit preferably incorporates a socket fed from its own plug, optionally via an internal fuze and/or a socket control switch.

The programmable sensor unit may also be adapted for remote control, especially in respect of heating level, by means of a portable controller.

In the event of solenoid valves being used, the valve control output of the unit is preferably of on/off (valve open/shut) form, instead of being of analogue form, with switching at a maximum rate low enough to avoid generating sonic irritation, e.g. at a maximum switching frequency of several minutes rather than seconds.

The actuator of the invention can be driven by any form of, e.g. AC, DC or pulsed, electrical valve control output.

The invention will be described further, by way of example, with reference to the accompanying drawings, wherein FIGURE 1 is a diagram which shows the arrangement of a system of the invention, FIGURE 2 shows a perspective view of the control unit of the system, and FIGURE 3 shows a schematic diagram of a valve actuator of the invention.

In the embodiment of the invention represented in FIGURE 1, the control system comprises an electrically actuated water flow control valve 10 to control the flow of water to a heat emitter 11, e.g. usually a radiator, and a control unit 12 to energise and de-energise the valve 10 via an electrical cable 13.

The control unit 12; shown also in FIGURE 2 comprises a housing 20 containing a programmer/controller microprocessor 21 (FIGURE 1), manually actuable input and setting means 22 and a temperature sensing means 23 to provide inputs to the microprocessor 21, and, optionally, a receiver 24, (to receive signals emitted by a manual remote control unit 25, FIGURE 1), and a room occupancy sensor 26 which can be integrated into the unit 12 or connected to the unit 12 by means of a socket 14 shown in FIGURE 2. The microprocessor 21 drives a display 27.

The input and setting means 22 provides buttons 28 for signalling the microprocessor 21, to input: (a) the day of the week e.g. the day to be programmed or the actual day, (b) the "on" time of day and the "off" time of day for a heating period on the set day, (c) further "on" and "off" times for further heating periods, (d) the desired temperature to be achieved during each set period, and (e) the current actual time and day of the week.

The day of the week may be simply represented by a sequence number of 1 to 7.

Insofar as the programming of the timing of the periods is concerned, the unit may employ technology known from 7 day programmable times, e.g. 7 day times such as some of those illustrated on page 44 of the Argos Catalogue No. 47/22 for Spring/Summer 1997. This technology can be adapted to enable temperature settings to be correlated with each "on" period setting. The microprocessor causes the display 27 to indicate each input and setting during programming, and, after programming is completed, to show the actual day, the time, whether the heating is set "on" or "off", and the set and/or actual temperature.

During the "on" periods the microprocessor in this embodiment compares the desired set temperature with the actual room temperature sensed by the means 23, and, if the set temperature is above the actual temperature, electronically actuates a switch 30 to supply electrical power from line 31 to the cable 13. In an alternative arrangement the actual comparison is performed by a comparator 29 of the unit which compares set and actual temperature inputs (provided by the microprocessor and the means 23 respectively) to actuate the switch 30. Switching hysteresis or delay is preferably built into the system so that it does not "hunt" rapidly when the room temperature approximates to the set temperature to avoid repetitive operation of the valve 10.

The means 22 also provides buttons 28 for input of mode settings including an "off" setting to override but not alter the programmed settings, for input of an "auto" setting to return the unit to a state in which it resumes programmed operation, and for an "on" setting in which the valve is actuated to an open state, irrespective of the programmed "on" periods, e.g. when the actual temperature is below the set temperature to give continuous thermostatic control.

The unit 12 also includes the receiver 24 to receive transmitted signals, e.g, an infra red, an ultrasound or other radiated signals, from the portable remote control unit having buttons 28 for alteration of at least the set temperature, and for remote setting of the "mode" settings of "on", "auto" and "off". The more sophisticated form of remote control unit 25 shown also provides a duplicate display 27 and manual input control buttons 28 (only some of which are indicated in FIGURE 1) for programming the microprocessor, using technology similar to that employed in some remote control units for video recorders.

The integral or detachable room occupancy sensor 26 provides signals to the microprocessor 21 or comparator 29 to indicate the presence or absence of a person in the room, within the field of view or scanning field of the sensor. These signals may be utilised as the mode setting "on" and "off" signals. The occupancy sensor in this embodiment divides the field of view into many zones, and, upon detection of a person moving from zone to zone delays sending an "on" mode signal for a predetermined or presettable time e.g. of a few minutes, and upon detection of a person in one or a few of the zones for a shorter predetermined time (e.g. of several seconds) issues an mode signal to provide heating when the person becomes sedentary in the room. Similarly, in the absence of any person in the room for a substantial, e.g. several minutes, period after the heating program has caused the heat to be turned on, the sensor 26 sends an "off" mode signal.

Instead of using such an intelligent occupancy sensor 26, the sensor may simply send a "person detected moving" signal, a "person detected not moving" signal and a "person not detected" signal to the microprocessor, which is programmed with said times and periods and to respond after the lapsing thereof for actuation of the valve.

The receiver 24, sensor 26 and provision therefore in the microprocessor and comparator, are optional.

The unit 12 is configured to include an electrical mains supply connector, which in this embodiment comprises a UK standard 3-pin plug 34 at the rear of the housing.

Within the unit 12, the microprocessor is powered from the plug 34 via a fuse 35, and a further fuse 36 protects the line 31, switch 30 and cable 13; and the housing optionally carries a standard socket outlet 37, optionally controlled by a switch 38, and optimally protected by the further fuse 36.

The valve 10 in the embodiment is a solenoid actuated form of by-pass control valve, which in the de-energised state flows some water to a radiator 40 (radiator "on"), and in the energised state flows water solely along a bypass line 41 (radiator "off"). The valve 10 has an actuator 50.

Referring to FIGURE 3, the actuator 50 serves as part of the electrically actuated water flow control valve 10 which is indicated partially in FIGURE 3 in broken lines.

The valve has a body 51 with an upwardly open formation 52 around the actuating shaft or jumper 53 of the valve. The formation 52 is externally threaded.

The actuator 50 has a hollow body 54 in which two bimetallic discs 55 and 56 are located by a bias spring 57, so that peripheral portions of the discs 55 and 56 embrace a carrier 58 therebetween. The carrier 58 carries an electrical resistance wire heating element 59 and electrical connector leads 60 to which the electrical cable 13 is connected. The leads 60 are covered by the carrier or a cover plate thereon where they pass between the peripheral portions of the discs 55 and 56. A dished supplementary disc 57A may be fixed centrally to the top of the disc 55 so that the periphery of the disc 57A abuts the top of the body 54.

The body 54 has a downwardly open formation 61 projecting from its bottom wall 62, which formation 61 has an internally threaded collar 61A to connect with the formation 52 to connect the valve and actuator bodies 51 and 54 together, so that an abutment device 63, mounted centrally on the disc 56, extends through the formation 61 to engage the shaft or jumper 53 of the valve.

In this embodiment, each bimetal disc 55,56 is approximately 3 cm in diameter and o.5 cm thick and gives a displacement of 0.4 mm with a thrust exceeding 3 Kgm when heated through a nominal actuation temperature range spanning across 30"C, which range (e.g. 50"C + 20"C to 80"C + 20"C) is set well above an unheated ambient temperature.

The total working displacement of the abutment 63 produced by the oppositely curving discs 55 and 56 is almost 1.0 mm, which is sufficient to depress the jumper 53 from a valve fully open position to a valve closed position when the discs are heated to about 80"C to 100 C. Thermal flexing of the supplementary disc 57A increases this working displacement.

Operation of the actuator at temperatures well above ambient reduces the influences of changes in ambient temperature upon the actuator, and allows a gap 65 to exist between the abutment device 63 and the jumper 53 when the bimetallic device is cold, e.g. not heated by the heating device, so that deflections of the abutment produced by ambient temperature changes are not transmitted to the jumper 53.

The cold gap 65 can be adjusted by varying the length of the device 63, which comprises an upper female threaded part and a lower male threaded part to permit such adjustment. However instead of, or in addition thereto, the depth of interengagement between the formations 52,61 may be adjustable to vary the gap 65.

The invention also includes and provides a thermostatic water valve provided with the actuator of the invention. The connector is preferably threaded and is provided with detent or retaining means to hold the body in a predetermined or selected position relative to the valve.

Said detent or retaining means can preferably be released or overcome to enable the body to be displaced further towards the valve so as to close the valve or restrict the valve opening for any given state of the heater device or thrust member.

The body is preferably insulated or made of insulating material.

The heater assembly preferably comprises a carrier having a peripheral portion embraced between the bimetallic discs. The element is preferably mounted on the carrier so as to extend across the carrier. Electrical supply connector leads are preferably mounted in or on the carrier so that they are protected by the carrier where they pass between the peripheral portions of the discs.

The actuator is preferably arranged so that the operational temperature range of the bimetallic discs is well above normal ambient temperature range.

The invention is not confined to details of the foregoing examples, and many variations and modifications are possible within the scope of the invention which provides and includes a control or heating system or a control unit having any novel part, feature or functional or operational configuration or mode of operation disclosed herein and/or in the accompanying drawings.

For example, other forms of electrically powered valves may be used instead including non-bypass forms of solenoid actuated valves, and motorised valves of bypass or non-bypass forms. The valve operation of such valves may be modulated so that its degree of opening may be varied in a controlled manner between zero (shut) and maximum (fully open) states in the flow path to the or each radiator, but such a form of operation could necessitate an electrical feedback to the unit 12 so that the microprocessor could take into account the state of the valve (or valves) as well as the heating demand determined by the microprocessor from the size of the difference between the set and sensed actual room temperatures.

Claims (18)

1. A control system for a hot water central heating system employing water filled heat emitters, and a boiler to heat said water which boiler is energised via a suitable control such as a switch or programmable timer, the control system being characterised in that it comprises: a) at least one electrically actuated valve (i.e. a valve having an electrically controlled actuator) which can be fitted to one of the radiators to control the flow of hot water through the radiator, b) a programmable sensor or control unit to actuate (e.g. energise and de-energise the actuator of) the valve via an electrical cable according to a plurality of predetermined parameters, the first one of which is temperature.

2. A system as claimed in Claim 1 wherein the sensor is of a form which can be plugged into a normal electrical supply socket.

3. A system as claimed in Claim 1 or 2 wherein the, or one, further parameter is timed in which the "on" periods (in which the valve is controlled by the sensed and set temperatures ) are presettable according to the expected occupancy of the particular room concerned.

4. A system as claimed in Claim 1, 2, or 3 wherein the or a further parameter, in the presence, absence or movement of a person (or any animal or significant size) in the room.

5. A system as claimed in Claim 1,2,3 or 4 wherein the programmable sensor is unitary.

6. A system as claimed in Claim 1,2,3, or 4 wherein the programmable sensor has an input connection to receive at least one signal from a further sensor.

7. A system as claimed in Claim 6 wherein the further sensor is an infra-red sensor disposed in a position to view a significant part of the room.

8. A system as claimed in Claim 7 wherein the infra-red sensor responds to movement of a person, or presence of a person, or both thereof, and is adapted to discriminate therebetween to give different signals, e.g. a low-heating requirement when a person is moving about in the room and a higher heat requirement signal when a person is sedentary in the room.

9. A system as claimed in Claim 5,6,7 or 8 wherein the sensor unit is programmable to permit a plurality of heating levels to be programmed, e.g. a low-heat requirement level at times when persons are expected to be active in the room and a high heat requirement at times when persons are expected to be sedentary in the room.

10. A system as claimed in Claim 5,6,6,8 or 9 wherein the programmable sensor unit is adapted for remote control, especially in respect of heating level, by means of a portable controller.

11. A system as claimed in any preceding claim wherein the actuator is in the form of a hollow body containing a bimetallic device and an electrical resistance heater assembly to heat the device, and comprising an abutment at one end of the bimetallic device so as to be engageable by a jumper or shaft of the water valve, and a hollow connector provided on the body to connect the body to the water valve, for actuation of the water valve by the abutment when the connector connects the body to the valve.

12. An actuator, for a water valve, in the form of a hollow body containing a bimetallic device and an electrical resistance heater assembly to heat the device, and comprising an abutment at one end of the bimetallic device so as to be engageable by a jumper or shaft of the water valve, and a hollow connector provided on the body to connect the body to the water valve, for actuation of the water valve by the abutment when the connector connects the body to the valve.

13. An actuator as claimed in Claim 12 or a system as claimed in Claim 11, wherein the actuator can be driven by any form of, e.g. AC, DC or pulsed, electrical valve control output.

14. An actuator as claimed in Claim 12 or 13 wherein the body encloses a bias spring to urge the bimetallic device towards a predetermined position.

15. An actuator as claimed in Claim 12, 13 or 14 wherein the bimetallic device includes a plurality of dished bimetallic discs which peripherally abut the heater assembly, and which are arranged to define therebetween a lenticular cavity in which a heating element of the heater assembly is located.

16. An actuator as claimed in Claim 12, 13, 14 or 15 wherein the centre portion of one disc carries the abutment and abuts a bias spring, and the centre portion of the other disc abuts the body or a supplementary disc.

17. An actuator as claimed in Claim 12, 13, 14, 15 or 16 wherein the discs are formed so as to increase their curvature when heated.

18. A system substantially as hereinbefore described with reference to FIGURES 1 or 2 or FIGURES 1 to 3 or an actuator substantially as hereinbefore described with reference to FIGURE 3 of the accompanying drawings.