Radiator balancing

Abstract

A device for automatically controlling the rate of flow of water out of a radiator in a central heating system is provided. The device includes a temperature sensor disposed within a conduit for detecting temperature of the water flowing out of the radiator and a valve connected to the temperature sensor and disposed within the conduit. The valve is movable to a closed position as the detected water temperature increases to a set point temperature, and to an open position as the detected water temperature decreases below the set point temperature.

Description

[0001] The present invention relates to a device for automatically controlling the rate of flow of water out of a radiator in a central heating system.BACKGROUND TO THE INVENTION

[0002] When installing a hydronic central heating system, the system needs to be balanced to allow the system as a whole to work efficiently and maximise heat distribution. Balancing is a method of ensuring that hot water from the boiler reaches all of the radiators in the system. It involves manually adjusting a fixed valve, e.g. a lockshield valve on each radiator, to make sure that all of the radiators heat up at the same speed.

[0003] An unbalanced central heating system can lead to some radiators (typically those furthest from the pump) taking a long time to heat up, while radiators close to the pump heat up very quickly. This means that to properly heat the building, the heating system needs to be switched on much earlier after a nighttime setback, for example. When the heating is switched on, the radiators in the rooms close to the pump will heat up quickly and start heating those rooms, while the radiators far from the pump do not receive much hot water. Eventually, if thermostatic radiator valves are fitted, the flow through the radiators close to the pump will be restricted, but this may take some time since the rooms need to heat up before this happens. The radiators in the further rooms will then start to receive more heat. It is possible that a room thermostat (typically in a hallway, which may be quite close to the pump) will trigger the boiler to switch off before this even happens. Another possible effect is that the room heated by the radiator close to the pump will heat up quickly, hence the heat transfer rate from the radiator into the room will be reduced, and hence the flow temperature of the water coming out of the radiator will not be much less than the flow temperature of the water going into the radiator. A high return temperature to the boiler may trigger the boiler flow thermostat to turn off the burner, even though parts of the building are still cold. Accordingly the whole building takes a long time to reach a comfortable temperature, or may never reach a comfortable temperature at all, with some rooms too hot and some rooms too cold. A householder may compensate for these effects by, for example, setting the room thermostat to its maximum setting to stop the boiler being shut off before all rooms are heated, setting the boiler flow thermostat to a high setting so that hot water is supplied even when the return temperature is high, and / or by setting the timer to turn the heating on a long time before it is required (e.g. a long time before they return from work in the evening) to give the system time to heat the building. All of these factors mean that an unbalanced system is likely to use more energy and cost more to run, as well as being ineffective and difficult to control.

[0004] Furthermore, in an unbalanced system, the temperature of the return flow to the boiler may often be too hot (i.e. not very much lower than it was when it left the boiler). Modern condensing boilers require a low flow temperature on the return for maximum efficiency. If the temperature of the water flowing out of the radiator is not at least 20°C lower than the temperature of the water from the boiler, the boiler will not be running at its most efficient.

[0005] In a properly balanced system, the lockshield valves are adjusted, typically to restrict the flow of water through the radiators that are close to the pump and hence allowing more water to flow to the furthest radiators. As a result, the radiators heat up at an even rate, the thermostatic control systems will be effective, and the heating system does not need to be turned on long before the building needs to be used. Furthermore, the return flow temperature of the boiler will be consistently at the lowest level it can be. This saves energy and money.

[0006] However, balancing is very time consuming, so it is rarely done correctly, if at all. The settings of the lockshield valves are only valid for one particular configuration. This means that if one radiator is turned off (e.g. by turning off the thermostatic radiator valve in an occasionally-used guest room), the whole system will be out of balance. Lockshield valves are sometimes used to isolate radiators, for example to take them off the wall for decorating. It is unlikely that the exact, correct, balanced position of the lockshield valve will be restored after the radiator is put back. For various reasons therefore, even a system which has been diligently balanced by the installer is unlikely to stay in its balanced state for very long.

[0007] It is known to provide a pressure independent control valve on a radiator inlet or outlet. These pressure independent control valves are sometimes integrated into the body of a thermostatic radiator valve. This type of valve aims to regulate the flow rate through the radiator, irrespective of the water pressure available (which will depend for example on which other radiators are turned on). However, these valves need to be set to match the size of the radiator, to set the flow rate accordingly. If this is not done, then the system will not be properly balanced. Also, even when these valves are installed and correctly set, inefficiencies remain. For example, when the heating system is first turned on, hot water will tend to rush through the system, especially through the radiators closest to the pump, without heating up all of the radiator. The return temperature at the boiler is therefore initially high, and the room is not heated up as quickly as it could be.

[0008] It is an object of the present invention to reduce or substantially obviate the aforementioned problems.STATEMENT OF INVENTION

[0009] According to a first aspect of the present invention, there is provided an automatic balancing device for controlling the rate of flow of water out of a radiator in a hydronic central heating system, the device comprising: a conduit having an inlet and an outlet, the inlet being in fluid connection with the outlet for allowing flow of water from the inlet to the outlet; a temperature sensor disposed within the conduit for detecting temperature of the water flowing out of the radiator; and a valve connected to the temperature sensor and disposed within the conduit for controlling flow from the inlet to the outlet, the valve being configured to move to a closed or restricted position as the detected water temperature increases to a set point temperature, and being configured to return to an open or relatively unrestricted position as the detected water temperature decreases below the set point temperature.

[0010] Advantageously, this removes the need for balancing the central heating system by manually adjusting a lockshield valve connected to each radiator. This is because the rate of flow of water out of each radiator in the system can instead be controlled automatically by the device. This allows the system to achieve higher or full efficiency. This also allows for even temperatures throughout the home or building, rather than certain radiators heating up quickly whilst the others remain colder. When the heating system is first turned on, hot water will generally flow quickly into radiators close to the pump. The water flows through these radiators and then returns to the boiler, having potentially only reduced in temperature slightly. By placing a device according to the invention on the outlet from the radiator, the flow is restricted when the flow out of the radiator is hot. Restricting the flow allows more of the heat in the water to be radiated into the room, and also allows more hot water from the boiler to reach radiators further from the pump. Hence the whole building is heated up more quickly. Furthermore, the return flow temperature to the boiler is optimal so that the boiler can operate at maximum efficiency.

[0011] The set point temperature may be chosen in order to target an ideal return flow temperature at the boiler. This may vary in different installations, for example according to the type of boiler and its power rating in relation to the size of the system.

[0012] In different embodiments, the valve may be closed (i.e. to completely block flow) at the set point temperature, but in most cases it is preferred that the maximally restricted position of the valve, at the set point temperature, is not fully closed but allows some, albeit restricted, flow through the radiator. In the open position, the valve allows relatively unrestricted flow.

[0013] The conduit may be in the form of a radiator tail. The inlet of the radiator tail may be adapted to connect to a radiator outlet. The outlet of the radiator tail may be adapted to connect to a radiator valve (such as a lockshield valve) or a return system circuit pipe of the system.

[0014] It is convenient to provide the automatic balancing valve in the form of a radiator tail, since the plumbing work to install a radiator with the valve is then no different to the work usually done to install a radiator with a standard lockshield and tail. Automatic balancing valves may also be retrofitted to existing systems, simply by removing the radiator tails and replacing them with radiator tails incorporating the balancing valve according to the invention.

[0015] A section of the conduit or radiator tail may have a threaded outer surface. The threaded section may be disposed next to the inlet. This allows the conduit or radiator tail to provide a secure threaded connection with the radiator outlet. Typically, radiators in the UK are provided with a 0.5inch BSP female thread, into which the threaded outer surface of the radiator tail can be inserted.

[0016] The temperature sensor may cause the valve to move to the closed (restricted) position or open (relatively unrestricted) position depending on the detected water temperature.

[0017] The temperature sensor may be for example in the form of a wax-filled or fluid-filled capsule, in which the fluid expands at higher temperatures.

[0018] The temperature sensor may increase or decrease in length axially along the conduit. For example, the temperature sensor may include a pin protruding from the fluid-filled capsule, so that expansion of the fluid in the capsule pushes the pin further out of the capsule.

[0019] The temperature sensor may increase in length causing the valve to move to the closed position as the detected water temperature increases to the set point temperature.

[0020] The temperature sensor may be disposed substantially centrally in the conduit, spaced from an inner surface of the conduit, so that water can flow around all sides of the temperature sensor. A retaining spacer, which may be threaded, may be provided between the temperature sensor and the conduit to support and retain the temperature sensor in position spaced from the walls of the conduit. The retaining spacer may be in the form of a ring having gaps or apertures to allow water to flow around the temperature sensor, between the temperature sensor and the conduit walls.

[0021] The temperature sensor may decrease in length causing the valve to move to the open (relatively unrestricted) position as the detected water temperature decreases.

[0022] This allows the temperature sensor to control the position of the valve depending on the detected water temperature via the temperature sensor's response to the changes in water temperature.

[0023] As the detected water temperature increases to the set point temperature, the valve gradually moves to the closed position, thus slowing the flow of water through the radiator. This restricts the flow of water out of the radiator and allows more time for the radiator to radiate heat from the water. It also allows more heat to reach other radiators, which may be further from the pump.

[0024] As the detected water temperature decreases, the valve gradually moves to the open position, thus speeding up the flow of water through the radiator. This allows more water to flow through the radiator so that the radiator heats up.

[0025] The valve may comprise a valve seat and a linearly-movable valve member.

[0026] The valve seat may be fixed to the inner surface of the conduit. In some embodiments, the position of the valve seat along the conduit may be movable to adjust the set point temperature.

[0027] The temperature sensor may move the valve member to sit against the valve seat in the closed position, as the temperature increases to the set point temperature.

[0028] The temperature sensor may move the valve member away from the valve seat into the open position as the temperature decreases.

[0029] The temperature sensor may be disposed next to the inlet of the conduit. This allows the temperature sensor to detect the temperature of the water coming straight out of the radiator outlet, in use.

[0030] The valve may be disposed next to the outlet of the conduit.

[0031] The valve seat may be disposed next to the outlet of the conduit.

[0032] The valve member may be the part of the valve which is connected to the temperature sensor and which moves as the temperature sensor changes in temperature. The valve member may be disposed between the valve seat and the temperature sensor.

[0033] The position of the valve member relative to the temperature sensor and the valve seat allows the valve member to be easily connected with the temperature sensor and thus allows the temperature sensor to easily move the valve member to the closed or open position, for example where the temperature sensor is in the form of a wax- or liquid-filled capsule which expands and pushes out a pin as the temperature rises.

[0034] A spring biasing the valve to the open position may be provided.

[0035] The spring may be disposed between the valve member and the valve seat of the valve, to urge the valve member away from the valve seat. When the temperature sensor (e.g. the fluid in the capsule) expands, the valve member is pushed, against the spring, to sit against the valve seat and close the valve. When the temperature sensor contracts, the spring returns the valve to the open position.

[0036] The valve may be adapted to set the temperature of the water flowing out of the radiator. This allows the device to control the temperature of water that can flow out of the radiator.

[0037] The valve may be adapted to be manually turned off. This completely prevents or stops the flow of water out of the radiator. This removes the need for a lockshield valve to be connected to the system to stop the flow of water out of the radiator. In other words, an external handle or screw, for example, may be provided, to lock the valve in the closed position irrespective of the temperature measured by the temperature sensor. This feature may be used to isolate a radiator when required.

[0038] The set point temperature may be adjustable, for example by moving the valve seat to a chosen position axially along the conduit, or by moving the temperature sensor axially along the conduit. Where either of these components is mounted to the conduit by a screw thread, this adjustment of the set point may be achieved for example by turning the respective component using a screwdriver or other tool inserted into the conduit through the inlet or the outlet. In other embodiments, a mechanism may be provided for adjusting the set point temperature using an external handle, allowing the set point temperature to be adjusted while the device remains connected to the radiator and heating system circuit.

[0039] The set point temperature may be a temperature for example of around 70°C, or between 60°C and 80°C depending on the system.

[0040] A return flow temperature (i.e. temperature of water flowing out of the radiator and back to the boiler) may be a temperature between 40°C and 60°C. A return flow temperature around this range, i.e. at about 20°C below the boiler flow temperature, whatever that may be, allows the system and its components to work more efficiently.

[0041] According to a second aspect of the present invention, there is provided a hydronic central heating system comprising: a boiler having a thermostat for setting the temperature of the water flowing out of the boiler; and two or more radiators, each radiator comprising: a thermostatic valve connected to a radiator inlet for detecting the air temperature in a room and controlling the flow of water into the radiator depending on the detected air temperature; and a device according to the first aspect of the present invention for detecting the temperature of the water flowing out of the radiator and controlling the flow of water out of the radiator depending on the detected water temperature.

[0042] The system may further include a room thermostat and / or a timer / programmer.

[0043] According to a third aspect of the present invention, there is provided a method of controlling flow of water through a hydronic heating system, the heating system comprising: a boiler having a thermostat for setting the temperature of the water flowing out of the boiler, and two or more radiators, the method comprising: providing a thermostatic valve on each radiator inlet for detecting the air temperature in a room and controlling the flow of water into the radiator depending on the detected air temperature, and providing a device according to the first aspect of the present invention on each radiator outlet for detecting temperature of the water flowing out of a radiator outlet and controlling the flow of water out of the radiator depending on the detected water temperature, causing the valve of the device to move to a closed position as the detected water temperature increases to the set point temperature or causing the valve to move to an open position as the detected water temperature decreases below the set point temperature.

[0044] The thermostatic radiator valves may restrict or close flow into the inlet of the radiator as the room heats up to its set temperature, as is well known. The devices on the radiator outlets on the other hand restrict the outlet flow (and hence the flow through the radiator) when the outlet water temperature is high.BRIEF DESCRIPTION OF THE DRAWINGS

[0045] For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which: Figure 1 shows a front view of the device according to the present invention connected to a radiator of a hydronic central heating system and a cross-sectional view of the device; Figure 2 shows a cross-sectional view of the device of Figure 1 in an open position; Figure 3 shows a cross-sectional view of the device of Figure 1 in a closed position; Figure 4 is a schematic of a central heating system comprising a boiler and several radiators, with a valve according to the invention installed on each radiator; Figure 5 is a perspective view of the device of Figure 1; Figure 6 is a cross section through another embodiment of the device according to the invention; and Figure 7 is an illustration showing how hot water flows through a cold radiator when a heating system is first turned on. DESCRIPTION OF PREFERRED EMBODIMENTS

[0046] Referring firstly to Figures 1 to 3, a device for automatically controlling the rate of flow of water out of a radiator 20 in a hydronic central heating system is generally indicated at 10.

[0047] The device 10 comprises a conduit 12, and a temperature sensor 14 and a valve 16 connected to each other and disposed within the conduit 12.

[0048] The conduit 12 is in the form of a radiator tail which is a connector for connecting to an outlet of the radiator, as shown in Figure 1. The radiator tail 12 is a tubular member and can be made from metal. The radiator tail 12 has an inlet 12a at one end and an outlet 12b at the opposite end, as can be more clearly seen in Figures 2 and 3.

[0049] In some embodiments, the inlet 12a of the radiator tail 12 can be connected to the radiator outlet and the outlet 12b of the radiator tail 12 can be connected to a radiator valve such as a lockshield valve. In other embodiments, the valve 16 of the device 10 removes the need for a radiator valve to be connected at the outlet end of the radiator 20, which will be discussed in more detail below. Thus, the outlet 12b of the radiator tail 12 can be connected directly to a return system circuit pipe 22 for returning water to a boiler in the heating system, as shown in Figure 1.

[0050] Once the radiator tail 12 is connected to the heating system, the water in the radiator 20 that has come from the boiler via a system circuit pipe 24 connected to the radiator inlet can flow out of the radiator 20 through the radiator outlet, and then through the inlet 12a of the radiator tail 12 and the outlet 12b of the radiator tail 12 and back to the boiler via the return system circuit pipe 22.

[0051] A portion of an outer surface of the radiator tail 12 disposed adjacent to the inlet 12a is threaded, as can be more clearly seen in figures 2 and 3. This allows the radiator tail 12 to be threaded to a complementary threaded portion around the radiator outlet. This allows the radiator tail 12 to be securely connected to the radiator 20.

[0052] The temperature sensor 14 is disposed close to the inlet 12a of the radiator tail 12. The temperature sensor 14 is spaced from an inner surface of the radiator tail 12. This allows the water to flow around the temperature sensor 14 on all sides, and prevents the temperature sensor 14 from blocking the flow of water through the radiator tail 12. The temperature sensor is supported on a support formation 15, to support and retain the temperature sensor 14 in a position spaced from the walls, substantially centrally in the conduit through the radiator tail. The support formation 15 has through channels or apertures to allow water to flow through the conduit, around the temperature sensor.

[0053] In this embodiment, the temperature sensor is screwed into the support formation 15.

[0054] The temperature sensor 14 is an elongate body extending axially along the radiator tail 12. The temperature sensor 14 comprises a first section 14a, a second section 14b having a smaller width or diameter than the first section 14a, and a third section 14c having a smaller width or diameter than both the first 14a and second 14b sections.

[0055] The temperature sensor may be in the form of a capsule containing, for example, wax, or another fluid which expands as it warms up. A pin 21 extends out of the capsule, so that as the fluid in the capsule expands, the pin is pushed further out of the capsule.

[0056] The first section 14a of the temperature sensor 14 is disposed directly next to the inlet 12a of the radiator tail 12. A portion of the first section 14a protrudes out of the inlet 12a of radiator tail 12. This allows the temperature sensor 14 to detect the temperature of the water coming straight from the radiator 20, in use. The second section 14b is disposed between the first 14a and third 14c sections of the temperature sensor 14.

[0057] The threaded section 13 of the radiator tail 12 has a substantially larger inner and outer diameter than an unthreaded section 15 of the radiator tail 12. This allows the first section 14a of the temperature sensor 14 to be disposed within the threaded section 13 of the radiator tail 12, and next to the inlet 12a of the radiator tail 12. The second 14b and third 14c sections of the temperature sensor 14 are disposed within the unthreaded section 15 of the radiator tail 12.

[0058] The valve 16 is disposed next to the outlet 12b of the radiator tail 12. The valve 16 includes a valve seat 16a and a valve member 16b. The valve seat 16a is disposed directly next to the outlet 12b of the radiator tail 12. The valve member 16b is disposed further within the radiator tail 12. In other words, the valve member 16b is disposed between the temperature sensor 14 and the valve seat 16a of the valve 16. The periphery of the valve seat 16a of the valve 16 is fixed to an inner surface of the radiator tail 12.

[0059] In other embodiments, the temperature sensor and valve may be disposed the other way around, i.e. with the temperature sensor close to the outlet of the conduit and the valve on the inlet side.

[0060] The pin 21 which extends out of the capsule of the temperature sensor 14 is disposed against the valve member 16b, so that in use when the fluid in the capsule expands, the pin pushes the valve member 16b against the valve seat 16a, closing the valve.

[0061] As the water temperature increases to a set point temperature, the pin 21 is pushed out of the capsule and moves the valve 16 to a closed position, as shown in Figure 3. The pin pushes the valve member 16b towards the valve seat 16a. This causes the valve member 16b to slide axially along the length of the radiator tail 12.

[0062] A protruding portion 19 of the valve member 16b is inserted within an aperture 17 extending through a central axis of the valve seat 16a and closes the valve 16. The shape of the aperture 17 of the valve seat 16a and the shape of the protruding portion 19 of the valve member 16b are complementary to each other. This means that when the valve 16 is in the closed position, the protruding portion 19 restricts the flow out through the aperture 17 of the fixed part 16a of the valve 16.

[0063] The valve 16 restricts the flow of water out of the radiator 20. The closer the valve member 16b is to the valve seat 16a, the slower is the flow of water out of the radiator 20. This allows more time for the water within the radiator 20 to radiate heat into a room of a building. This allows the water leaving the radiator 20 to be colder than the water flowing into the radiator 20.

[0064] As the water temperature decreases, the fluid in the temperature sensor 14 contracts, and the spring 18 pushes the valve member 16b back to the open position, as shown in Figure 2. The pin 21 is pushed back inside the capsule by the force of the spring 18. Hence the valve is open and flow of water through the radiator 20 is increased.

[0065] The set point temperature may be settable by an installer or user. This may be done for example by moving the valve seat 16a axially along the conduit. Moving the valve seat towards the valve member 16b and temperature sensor 14 (i.e. to the left in the drawings) will decrease the set point temperature, since the amount of expansion of the fluid in the capsule which is required to push the pin far enough to close the valve will be reduced. Conversely, moving the valve seat away from the valve member 16b (i.e. to the right in the drawings) will increase the set point temperature, since a greater amount of expansion of the fluid in the capsule is then required to push the valve member 16b all the way against the valve seat 16a.

[0066] The valve seat may be axially movable, for example if it is screw-threaded to the inside of the conduit. A slot may be provided so that the valve seat can be turned using a screwdriver, for example, inserted through the outlet of the conduit on the right-hand side of the drawings, to set the position of the valve seat and hence set the set point temperature. In other embodiments, a mechanism may be provided for moving the valve seat by means of an external handle, so that the set point temperature can be set after installation of the device to a radiator, without disassembly.

[0067] A spring 18 attached to and disposed between the valve member 16b and the valve seat 16a biases the valve 16 to the open position. This returns the pin 21 into the capsule once the fluid in the capsule has cooled down and contracted.

[0068] In some embodiments, means may be provided for manually turning off the valve 16. For example, an external handle and a corresponding mechanism may be provided to manually force the valve member 16b against the valve seat 16a, irrespective of the temperature of the fluid in the conduit. This means that the valve 16 can be set to completely prevent flow of water out of the radiator 20, and hence used to isolate the radiator from the system completely.

[0069] Referring now to Figure 4, a central heating system is shown. The central heating system includes a boiler 100 which in this case includes a pump 104, although the invention is equally applicable to systems which use an external pump. Water is heated in the heat exchanger 106 of the boiler, and flows along the flow pipe marked F, to the radiators 20. A boiler flow thermostat 102 regulates the temperature of the water when it leaves the boiler 100 to a setpoint flow temperature, which may be for example between 60°C and 80°C.

[0070] The inlet of each radiator is connected to the flow pipe F by an inlet pipe 24. Between the inlet pipe 24 and the radiator inlet, a thermostatic radiator valve 30 is provided. A thermostatic radiator valve measures the air temperature in the room to modulate the flow into the radiator to achieve a setpoint room temperature. The thermostatic radiator valves may be mechanical or electronic, and in some cases may communicate with external room temperature sensors.

[0071] The outlet of each radiator is connected to the return pipe R by a radiator outlet pipe 22. Between the radiator outlet and the outlet pipe 22, an automatic balancing valve device 10 as described above is provided. The automatic balancing valve device 10 is essentially in the form of a radiator tail, and as shown in Figure 4 is disposed between the radiator outlet and a conventional lockshield valve 32.

[0072] When the building is cold and the heating system is first turned on, all valves are likely to be open, although the setpoint of the thermostatic valves 30 may be set to different temperatures (for example, so that a living room is warmer than a bedroom). Likewise, the water in the flow pipe F is cold and so the valves in the automatic balancing devices 10 will also be open. Water therefore flows freely into all radiators. However, it will be seen that radiators close to the pump will receive a higher flow and will tend to heat up faster. Initially, hot water will flow through the radiator closest to the pump relatively quickly, and this may mean that the temperature of the water flowing through the respective automatic balancing device is relatively high. However, the automatic balancing device reacts quickly to restrict the flow. This will ensure that the flow through the radiator close to the pump is restricted so that more heat from the water is given out to the room, and also that radiators further from the pump receive a share of the heat from the boiler.

[0073] The set point temperature of each device 10 may be adjusted to suit the particular requirements of the central heating system. It is envisaged that all of the devices 10 in a particular system will be set to the same set point temperature, which will depend on the flow temperature required in the system. Boilers will generally operate more efficiently with lower flow temperatures, but the flow temperature does need to be set high enough to adequately heat the building, and higher flow temperatures may be required for example in poorly-insulated buildings with undersized radiators. Figure 5 shows the device 10, in particular showing the back of valve seat 16a. Blind holes 23 are provided in a back surface of the valve seat 16a, so that a pin spanner may be used to turn the valve seat 16a, moving it on its mounting thread so that its longitudinal position along the conduit may be adjusted. This adjusts the set point temperature.

[0074] The device 10 can be retrofitted into the heating system, for example wherein an old radiator tail is removed, and the device 10 is connected to the heating system as a replacement.

[0075] Referring to Figure 6, another embodiment of the device is generally indicated at 200. This embodiment is similar to the one shown in Figures 1 to 5 but the valve 216 is disposed next to the inlet 212a of the conduit 212, and the temperature sensor 214 is disposed next to the outlet 212b of the conduit 212.

[0076] In addition, the device 200 is provided in a separate housing 222 designed to be installed in place of a lockshield valve, rather than being in the form of a radiator tail.

[0077] Two substantially parallel flow passages are formed within a section of the housing 222. A first flow passage 211 connects an outlet of an existing radiator tail 213 of the system to the inlet 212a of the conduit 212. A second flow passage 215 forms the conduit in which the valve is disposed. The wall of the conduit 212 separates the first and second flow passages.

[0078] A first section of the conduit 212 i.e. between the inlet 212a and a central region of the conduit 212 has a smaller diameter or width than a second section of the conduit 212 i.e. between the central region and the outlet 212b of the conduit 212. This forms a space between the wall of the housing 222 and the wall of the conduit 212 which forms the first flow passage 211. The channel or aperture within the conduit 212 of the device 200 forms the second flow passage 215.

[0079] In use, the water from a radiator flows through the existing radiator tail and through the first flow passage 211, through the valve to the second flow passage 215 and then back to the boiler via the return system circuit pipe. As the temperature increases to the set point temperature, the temperature sensor 214 moves the valve 216 to the closed position i.e. the temperature sensor 214 moves the valve member 216b upwards to sit against the valve seat 216a.

[0080] As the temperature decreases from the set point temperature, the temperature sensor 214 moves the valve 216 to the open position i.e. the temperature sensor 214 moves the valve member 216b downwards away from the valve seat 216a.

[0081] In this embodiment, an external handle 230 is provided. The external handle 230 controls the position of a second valve member 232, which can act to close the valve 216 by coming against the valve seat 216a from the side of the valve seat 216a which faces away from the first valve member 216b. In other words, the valve comprises a two-sided valve seat and can be closed either by the automatic temperature controlled valve member on one side (the underside as shown in Figure 6) or by the manual handle controlled valve member on the other side (the upper side as shown in Figure 6). The device 200 shown in Figure 6 can therefore be used to replace a conventional lockshield valve, and may be used to shut of the radiator altogether, for example if it needs to be removed for decorating.

[0082] Overall, the use of these devices allows the central heating system as a whole to work effectively and efficiently. The devices of the invention work together with conventional thermostatic radiator valves (which are installed on the inlets of the radiators) to ensure a dynamically balanced system, which will heat up all rooms quickly to the room temperature set by the thermostatic radiator valves. The automatic balancing valves of the invention ensure that, during the heat-up phase after the system has been off for some time, all radiators in the system receive hot water and all radiators give out heat to rooms, irrespective of the distance of each radiator from the pump. The valve of the invention also ensures a suitable temperature drop across the radiators, and hence a return temperature to the boiler which is much lower than the flow temperature from the boiler. This decreases the cost and energy used up by the system.

[0083] Figure 7 illustrates what typically happens when a central heating system is switched on and hot water rushes into a cold radiator. As is usually the case in the UK, the radiator is connected to the heating system circuit at opposing bottom corners. In Figure 7, the inlet to the radiator is on the bottom left corner and the outlet is on the bottom right corner.

[0084] As can be seen from Figure 7, heat from hot water entering the radiator first spreads along the left-hand side and bottom side of the radiator. These parts are the hottest parts of the radiator and are illustrated in red. The coldest parts of the radiator are illustrated in blue, and are mostly in the right section of the radiator. The heat then slowly spreads along the top side of the radiator, and also upwards from right to left (illustrated in green / yellowish red) until the radiator is evenly heated. However, before the radiator is evenly heater, a significant amount of hot water flows out of the outlet, even when (in this example) most of the top-right region of the radiator is still cold. This is wasteful. A device according to the invention increases the efficiency of the system by restricting the flow of hot water on the outlet, allowing the time for the heat to spread throughout the radiator. This makes more efficient use of the heat in the water which has been heated by the boiler.

[0085] The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Examples

Embodiment Construction

[0046]Referring firstly to Figures 1 to 3, a device for automatically controlling the rate of flow of water out of a radiator 20 in a hydronic central heating system is generally indicated at 10.

[0047]The device 10 comprises a conduit 12, and a temperature sensor 14 and a valve 16 connected to each other and disposed within the conduit 12.

[0048]The conduit 12 is in the form of a radiator tail which is a connector for connecting to an outlet of the radiator, as shown in Figure 1. The radiator tail 12 is a tubular member and can be made from metal. The radiator tail 12 has an inlet 12a at one end and an outlet 12b at the opposite end, as can be more clearly seen in Figures 2 and 3.

[0049]In some embodiments, the inlet 12a of the radiator tail 12 can be connected to the radiator outlet and the outlet 12b of the radiator tail 12 can be connected to a radiator valve such as a lockshield valve. In other embodiments, the valve 16 of the device 10 removes the need for a radiator valve to be ...

[0001] The present invention relates to a device for automatically controlling the rate of flow of water out of a radiator in a central heating system.BACKGROUND TO THE INVENTION

[0002] When installing a hydronic central heating system, the system needs to be balanced to allow the system as a whole to work efficiently and maximise heat distribution. Balancing is a method of ensuring that hot water from the boiler reaches all of the radiators in the system. It involves manually adjusting a fixed valve, e.g. a lockshield valve on each radiator, to make sure that all of the radiators heat up at the same speed.

[0003] An unbalanced central heating system can lead to some radiators (typically those furthest from the pump) taking a long time to heat up, while radiators close to the pump heat up very quickly. This means that to properly heat the building, the heating system needs to be switched on much earlier after a nighttime setback, for example. When the heating is switched on, the radiators in the rooms close to the pump will heat up quickly and start heating those rooms, while the radiators far from the pump do not receive much hot water. Eventually, if thermostatic radiator valves are fitted, the flow through the radiators close to the pump will be restricted, but this may take some time since the rooms need to heat up before this happens. The radiators in the further rooms will then start to receive more heat. It is possible that a room thermostat (typically in a hallway, which may be quite close to the pump) will trigger the boiler to switch off before this even happens. Another possible effect is that the room heated by the radiator close to the pump will heat up quickly, hence the heat transfer rate from the radiator into the room will be reduced, and hence the flow temperature of the water coming out of the radiator will not be much less than the flow temperature of the water going into the radiator. A high return temperature to the boiler may trigger the boiler flow thermostat to turn off the burner, even though parts of the building are still cold. Accordingly the whole building takes a long time to reach a comfortable temperature, or may never reach a comfortable temperature at all, with some rooms too hot and some rooms too cold. A householder may compensate for these effects by, for example, setting the room thermostat to its maximum setting to stop the boiler being shut off before all rooms are heated, setting the boiler flow thermostat to a high setting so that hot water is supplied even when the return temperature is high, and / or by setting the timer to turn the heating on a long time before it is required (e.g. a long time before they return from work in the evening) to give the system time to heat the building. All of these factors mean that an unbalanced system is likely to use more energy and cost more to run, as well as being ineffective and difficult to control.

[0004] Furthermore, in an unbalanced system, the temperature of the return flow to the boiler may often be too hot (i.e. not very much lower than it was when it left the boiler). Modern condensing boilers require a low flow temperature on the return for maximum efficiency. If the temperature of the water flowing out of the radiator is not at least 20°C lower than the temperature of the water from the boiler, the boiler will not be running at its most efficient.

[0005] In a properly balanced system, the lockshield valves are adjusted, typically to restrict the flow of water through the radiators that are close to the pump and hence allowing more water to flow to the furthest radiators. As a result, the radiators heat up at an even rate, the thermostatic control systems will be effective, and the heating system does not need to be turned on long before the building needs to be used. Furthermore, the return flow temperature of the boiler will be consistently at the lowest level it can be. This saves energy and money.

[0006] However, balancing is very time consuming, so it is rarely done correctly, if at all. The settings of the lockshield valves are only valid for one particular configuration. This means that if one radiator is turned off (e.g. by turning off the thermostatic radiator valve in an occasionally-used guest room), the whole system will be out of balance. Lockshield valves are sometimes used to isolate radiators, for example to take them off the wall for decorating. It is unlikely that the exact, correct, balanced position of the lockshield valve will be restored after the radiator is put back. For various reasons therefore, even a system which has been diligently balanced by the installer is unlikely to stay in its balanced state for very long.

[0007] It is known to provide a pressure independent control valve on a radiator inlet or outlet. These pressure independent control valves are sometimes integrated into the body of a thermostatic radiator valve. This type of valve aims to regulate the flow rate through the radiator, irrespective of the water pressure available (which will depend for example on which other radiators are turned on). However, these valves need to be set to match the size of the radiator, to set the flow rate accordingly. If this is not done, then the system will not be properly balanced. Also, even when these valves are installed and correctly set, inefficiencies remain. For example, when the heating system is first turned on, hot water will tend to rush through the system, especially through the radiators closest to the pump, without heating up all of the radiator. The return temperature at the boiler is therefore initially high, and the room is not heated up as quickly as it could be.

[0008] It is an object of the present invention to reduce or substantially obviate the aforementioned problems.STATEMENT OF INVENTION

[0009] According to a first aspect of the present invention, there is provided an automatic balancing device for controlling the rate of flow of water out of a radiator in a hydronic central heating system, the device comprising: a conduit having an inlet and an outlet, the inlet being in fluid connection with the outlet for allowing flow of water from the inlet to the outlet; a temperature sensor disposed within the conduit for detecting temperature of the water flowing out of the radiator; and a valve connected to the temperature sensor and disposed within the conduit for controlling flow from the inlet to the outlet, the valve being configured to move to a closed or restricted position as the detected water temperature increases to a set point temperature, and being configured to return to an open or relatively unrestricted position as the detected water temperature decreases below the set point temperature.

[0010] Advantageously, this removes the need for balancing the central heating system by manually adjusting a lockshield valve connected to each radiator. This is because the rate of flow of water out of each radiator in the system can instead be controlled automatically by the device. This allows the system to achieve higher or full efficiency. This also allows for even temperatures throughout the home or building, rather than certain radiators heating up quickly whilst the others remain colder. When the heating system is first turned on, hot water will generally flow quickly into radiators close to the pump. The water flows through these radiators and then returns to the boiler, having potentially only reduced in temperature slightly. By placing a device according to the invention on the outlet from the radiator, the flow is restricted when the flow out of the radiator is hot. Restricting the flow allows more of the heat in the water to be radiated into the room, and also allows more hot water from the boiler to reach radiators further from the pump. Hence the whole building is heated up more quickly. Furthermore, the return flow temperature to the boiler is optimal so that the boiler can operate at maximum efficiency.

[0011] The set point temperature may be chosen in order to target an ideal return flow temperature at the boiler. This may vary in different installations, for example according to the type of boiler and its power rating in relation to the size of the system.

[0012] In different embodiments, the valve may be closed (i.e. to completely block flow) at the set point temperature, but in most cases it is preferred that the maximally restricted position of the valve, at the set point temperature, is not fully closed but allows some, albeit restricted, flow through the radiator. In the open position, the valve allows relatively unrestricted flow.

[0013] The conduit may be in the form of a radiator tail. The inlet of the radiator tail may be adapted to connect to a radiator outlet. The outlet of the radiator tail may be adapted to connect to a radiator valve (such as a lockshield valve) or a return system circuit pipe of the system.

[0014] It is convenient to provide the automatic balancing valve in the form of a radiator tail, since the plumbing work to install a radiator with the valve is then no different to the work usually done to install a radiator with a standard lockshield and tail. Automatic balancing valves may also be retrofitted to existing systems, simply by removing the radiator tails and replacing them with radiator tails incorporating the balancing valve according to the invention.

[0015] A section of the conduit or radiator tail may have a threaded outer surface. The threaded section may be disposed next to the inlet. This allows the conduit or radiator tail to provide a secure threaded connection with the radiator outlet. Typically, radiators in the UK are provided with a 0.5inch BSP female thread, into which the threaded outer surface of the radiator tail can be inserted.

[0016] The temperature sensor may cause the valve to move to the closed (restricted) position or open (relatively unrestricted) position depending on the detected water temperature.

[0017] The temperature sensor may be for example in the form of a wax-filled or fluid-filled capsule, in which the fluid expands at higher temperatures.

[0018] The temperature sensor may increase or decrease in length axially along the conduit. For example, the temperature sensor may include a pin protruding from the fluid-filled capsule, so that expansion of the fluid in the capsule pushes the pin further out of the capsule.

[0019] The temperature sensor may increase in length causing the valve to move to the closed position as the detected water temperature increases to the set point temperature.

[0020] The temperature sensor may be disposed substantially centrally in the conduit, spaced from an inner surface of the conduit, so that water can flow around all sides of the temperature sensor. A retaining spacer, which may be threaded, may be provided between the temperature sensor and the conduit to support and retain the temperature sensor in position spaced from the walls of the conduit. The retaining spacer may be in the form of a ring having gaps or apertures to allow water to flow around the temperature sensor, between the temperature sensor and the conduit walls.

[0021] The temperature sensor may decrease in length causing the valve to move to the open (relatively unrestricted) position as the detected water temperature decreases.

[0022] This allows the temperature sensor to control the position of the valve depending on the detected water temperature via the temperature sensor's response to the changes in water temperature.

[0023] As the detected water temperature increases to the set point temperature, the valve gradually moves to the closed position, thus slowing the flow of water through the radiator. This restricts the flow of water out of the radiator and allows more time for the radiator to radiate heat from the water. It also allows more heat to reach other radiators, which may be further from the pump.

[0024] As the detected water temperature decreases, the valve gradually moves to the open position, thus speeding up the flow of water through the radiator. This allows more water to flow through the radiator so that the radiator heats up.

[0025] The valve may comprise a valve seat and a linearly-movable valve member.

[0026] The valve seat may be fixed to the inner surface of the conduit. In some embodiments, the position of the valve seat along the conduit may be movable to adjust the set point temperature.

[0027] The temperature sensor may move the valve member to sit against the valve seat in the closed position, as the temperature increases to the set point temperature.

[0028] The temperature sensor may move the valve member away from the valve seat into the open position as the temperature decreases.

[0029] The temperature sensor may be disposed next to the inlet of the conduit. This allows the temperature sensor to detect the temperature of the water coming straight out of the radiator outlet, in use.

[0030] The valve may be disposed next to the outlet of the conduit.

[0031] The valve seat may be disposed next to the outlet of the conduit.

[0032] The valve member may be the part of the valve which is connected to the temperature sensor and which moves as the temperature sensor changes in temperature. The valve member may be disposed between the valve seat and the temperature sensor.

[0033] The position of the valve member relative to the temperature sensor and the valve seat allows the valve member to be easily connected with the temperature sensor and thus allows the temperature sensor to easily move the valve member to the closed or open position, for example where the temperature sensor is in the form of a wax- or liquid-filled capsule which expands and pushes out a pin as the temperature rises.

[0034] A spring biasing the valve to the open position may be provided.

[0035] The spring may be disposed between the valve member and the valve seat of the valve, to urge the valve member away from the valve seat. When the temperature sensor (e.g. the fluid in the capsule) expands, the valve member is pushed, against the spring, to sit against the valve seat and close the valve. When the temperature sensor contracts, the spring returns the valve to the open position.

[0036] The valve may be adapted to set the temperature of the water flowing out of the radiator. This allows the device to control the temperature of water that can flow out of the radiator.

[0037] The valve may be adapted to be manually turned off. This completely prevents or stops the flow of water out of the radiator. This removes the need for a lockshield valve to be connected to the system to stop the flow of water out of the radiator. In other words, an external handle or screw, for example, may be provided, to lock the valve in the closed position irrespective of the temperature measured by the temperature sensor. This feature may be used to isolate a radiator when required.

[0038] The set point temperature may be adjustable, for example by moving the valve seat to a chosen position axially along the conduit, or by moving the temperature sensor axially along the conduit. Where either of these components is mounted to the conduit by a screw thread, this adjustment of the set point may be achieved for example by turning the respective component using a screwdriver or other tool inserted into the conduit through the inlet or the outlet. In other embodiments, a mechanism may be provided for adjusting the set point temperature using an external handle, allowing the set point temperature to be adjusted while the device remains connected to the radiator and heating system circuit.

[0039] The set point temperature may be a temperature for example of around 70°C, or between 60°C and 80°C depending on the system.

[0040] A return flow temperature (i.e. temperature of water flowing out of the radiator and back to the boiler) may be a temperature between 40°C and 60°C. A return flow temperature around this range, i.e. at about 20°C below the boiler flow temperature, whatever that may be, allows the system and its components to work more efficiently.

[0041] According to a second aspect of the present invention, there is provided a hydronic central heating system comprising: a boiler having a thermostat for setting the temperature of the water flowing out of the boiler; and two or more radiators, each radiator comprising: a thermostatic valve connected to a radiator inlet for detecting the air temperature in a room and controlling the flow of water into the radiator depending on the detected air temperature; and a device according to the first aspect of the present invention for detecting the temperature of the water flowing out of the radiator and controlling the flow of water out of the radiator depending on the detected water temperature.

[0042] The system may further include a room thermostat and / or a timer / programmer.

[0043] According to a third aspect of the present invention, there is provided a method of controlling flow of water through a hydronic heating system, the heating system comprising: a boiler having a thermostat for setting the temperature of the water flowing out of the boiler, and two or more radiators, the method comprising: providing a thermostatic valve on each radiator inlet for detecting the air temperature in a room and controlling the flow of water into the radiator depending on the detected air temperature, and providing a device according to the first aspect of the present invention on each radiator outlet for detecting temperature of the water flowing out of a radiator outlet and controlling the flow of water out of the radiator depending on the detected water temperature, causing the valve of the device to move to a closed position as the detected water temperature increases to the set point temperature or causing the valve to move to an open position as the detected water temperature decreases below the set point temperature.

[0044] The thermostatic radiator valves may restrict or close flow into the inlet of the radiator as the room heats up to its set temperature, as is well known. The devices on the radiator outlets on the other hand restrict the outlet flow (and hence the flow through the radiator) when the outlet water temperature is high.BRIEF DESCRIPTION OF THE DRAWINGS

[0045] For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which: Figure 1 shows a front view of the device according to the present invention connected to a radiator of a hydronic central heating system and a cross-sectional view of the device; Figure 2 shows a cross-sectional view of the device of Figure 1 in an open position; Figure 3 shows a cross-sectional view of the device of Figure 1 in a closed position; Figure 4 is a schematic of a central heating system comprising a boiler and several radiators, with a valve according to the invention installed on each radiator; Figure 5 is a perspective view of the device of Figure 1; Figure 6 is a cross section through another embodiment of the device according to the invention; and Figure 7 is an illustration showing how hot water flows through a cold radiator when a heating system is first turned on. DESCRIPTION OF PREFERRED EMBODIMENTS

[0046] Referring firstly to Figures 1 to 3, a device for automatically controlling the rate of flow of water out of a radiator 20 in a hydronic central heating system is generally indicated at 10.

[0047] The device 10 comprises a conduit 12, and a temperature sensor 14 and a valve 16 connected to each other and disposed within the conduit 12.

[0048] The conduit 12 is in the form of a radiator tail which is a connector for connecting to an outlet of the radiator, as shown in Figure 1. The radiator tail 12 is a tubular member and can be made from metal. The radiator tail 12 has an inlet 12a at one end and an outlet 12b at the opposite end, as can be more clearly seen in Figures 2 and 3.

[0049] In some embodiments, the inlet 12a of the radiator tail 12 can be connected to the radiator outlet and the outlet 12b of the radiator tail 12 can be connected to a radiator valve such as a lockshield valve. In other embodiments, the valve 16 of the device 10 removes the need for a radiator valve to be connected at the outlet end of the radiator 20, which will be discussed in more detail below. Thus, the outlet 12b of the radiator tail 12 can be connected directly to a return system circuit pipe 22 for returning water to a boiler in the heating system, as shown in Figure 1.

[0050] Once the radiator tail 12 is connected to the heating system, the water in the radiator 20 that has come from the boiler via a system circuit pipe 24 connected to the radiator inlet can flow out of the radiator 20 through the radiator outlet, and then through the inlet 12a of the radiator tail 12 and the outlet 12b of the radiator tail 12 and back to the boiler via the return system circuit pipe 22.

[0051] A portion of an outer surface of the radiator tail 12 disposed adjacent to the inlet 12a is threaded, as can be more clearly seen in figures 2 and 3. This allows the radiator tail 12 to be threaded to a complementary threaded portion around the radiator outlet. This allows the radiator tail 12 to be securely connected to the radiator 20.

[0052] The temperature sensor 14 is disposed close to the inlet 12a of the radiator tail 12. The temperature sensor 14 is spaced from an inner surface of the radiator tail 12. This allows the water to flow around the temperature sensor 14 on all sides, and prevents the temperature sensor 14 from blocking the flow of water through the radiator tail 12. The temperature sensor is supported on a support formation 15, to support and retain the temperature sensor 14 in a position spaced from the walls, substantially centrally in the conduit through the radiator tail. The support formation 15 has through channels or apertures to allow water to flow through the conduit, around the temperature sensor.

[0053] In this embodiment, the temperature sensor is screwed into the support formation 15.

[0054] The temperature sensor 14 is an elongate body extending axially along the radiator tail 12. The temperature sensor 14 comprises a first section 14a, a second section 14b having a smaller width or diameter than the first section 14a, and a third section 14c having a smaller width or diameter than both the first 14a and second 14b sections.

[0055] The temperature sensor may be in the form of a capsule containing, for example, wax, or another fluid which expands as it warms up. A pin 21 extends out of the capsule, so that as the fluid in the capsule expands, the pin is pushed further out of the capsule.

[0056] The first section 14a of the temperature sensor 14 is disposed directly next to the inlet 12a of the radiator tail 12. A portion of the first section 14a protrudes out of the inlet 12a of radiator tail 12. This allows the temperature sensor 14 to detect the temperature of the water coming straight from the radiator 20, in use. The second section 14b is disposed between the first 14a and third 14c sections of the temperature sensor 14.

[0057] The threaded section 13 of the radiator tail 12 has a substantially larger inner and outer diameter than an unthreaded section 15 of the radiator tail 12. This allows the first section 14a of the temperature sensor 14 to be disposed within the threaded section 13 of the radiator tail 12, and next to the inlet 12a of the radiator tail 12. The second 14b and third 14c sections of the temperature sensor 14 are disposed within the unthreaded section 15 of the radiator tail 12.

[0058] The valve 16 is disposed next to the outlet 12b of the radiator tail 12. The valve 16 includes a valve seat 16a and a valve member 16b. The valve seat 16a is disposed directly next to the outlet 12b of the radiator tail 12. The valve member 16b is disposed further within the radiator tail 12. In other words, the valve member 16b is disposed between the temperature sensor 14 and the valve seat 16a of the valve 16. The periphery of the valve seat 16a of the valve 16 is fixed to an inner surface of the radiator tail 12.

[0059] In other embodiments, the temperature sensor and valve may be disposed the other way around, i.e. with the temperature sensor close to the outlet of the conduit and the valve on the inlet side.

[0060] The pin 21 which extends out of the capsule of the temperature sensor 14 is disposed against the valve member 16b, so that in use when the fluid in the capsule expands, the pin pushes the valve member 16b against the valve seat 16a, closing the valve.

[0061] As the water temperature increases to a set point temperature, the pin 21 is pushed out of the capsule and moves the valve 16 to a closed position, as shown in Figure 3. The pin pushes the valve member 16b towards the valve seat 16a. This causes the valve member 16b to slide axially along the length of the radiator tail 12.

[0062] A protruding portion 19 of the valve member 16b is inserted within an aperture 17 extending through a central axis of the valve seat 16a and closes the valve 16. The shape of the aperture 17 of the valve seat 16a and the shape of the protruding portion 19 of the valve member 16b are complementary to each other. This means that when the valve 16 is in the closed position, the protruding portion 19 restricts the flow out through the aperture 17 of the fixed part 16a of the valve 16.

[0063] The valve 16 restricts the flow of water out of the radiator 20. The closer the valve member 16b is to the valve seat 16a, the slower is the flow of water out of the radiator 20. This allows more time for the water within the radiator 20 to radiate heat into a room of a building. This allows the water leaving the radiator 20 to be colder than the water flowing into the radiator 20.

[0064] As the water temperature decreases, the fluid in the temperature sensor 14 contracts, and the spring 18 pushes the valve member 16b back to the open position, as shown in Figure 2. The pin 21 is pushed back inside the capsule by the force of the spring 18. Hence the valve is open and flow of water through the radiator 20 is increased.

[0065] The set point temperature may be settable by an installer or user. This may be done for example by moving the valve seat 16a axially along the conduit. Moving the valve seat towards the valve member 16b and temperature sensor 14 (i.e. to the left in the drawings) will decrease the set point temperature, since the amount of expansion of the fluid in the capsule which is required to push the pin far enough to close the valve will be reduced. Conversely, moving the valve seat away from the valve member 16b (i.e. to the right in the drawings) will increase the set point temperature, since a greater amount of expansion of the fluid in the capsule is then required to push the valve member 16b all the way against the valve seat 16a.

[0066] The valve seat may be axially movable, for example if it is screw-threaded to the inside of the conduit. A slot may be provided so that the valve seat can be turned using a screwdriver, for example, inserted through the outlet of the conduit on the right-hand side of the drawings, to set the position of the valve seat and hence set the set point temperature. In other embodiments, a mechanism may be provided for moving the valve seat by means of an external handle, so that the set point temperature can be set after installation of the device to a radiator, without disassembly.

[0067] A spring 18 attached to and disposed between the valve member 16b and the valve seat 16a biases the valve 16 to the open position. This returns the pin 21 into the capsule once the fluid in the capsule has cooled down and contracted.

[0068] In some embodiments, means may be provided for manually turning off the valve 16. For example, an external handle and a corresponding mechanism may be provided to manually force the valve member 16b against the valve seat 16a, irrespective of the temperature of the fluid in the conduit. This means that the valve 16 can be set to completely prevent flow of water out of the radiator 20, and hence used to isolate the radiator from the system completely.

[0069] Referring now to Figure 4, a central heating system is shown. The central heating system includes a boiler 100 which in this case includes a pump 104, although the invention is equally applicable to systems which use an external pump. Water is heated in the heat exchanger 106 of the boiler, and flows along the flow pipe marked F, to the radiators 20. A boiler flow thermostat 102 regulates the temperature of the water when it leaves the boiler 100 to a setpoint flow temperature, which may be for example between 60°C and 80°C.

[0070] The inlet of each radiator is connected to the flow pipe F by an inlet pipe 24. Between the inlet pipe 24 and the radiator inlet, a thermostatic radiator valve 30 is provided. A thermostatic radiator valve measures the air temperature in the room to modulate the flow into the radiator to achieve a setpoint room temperature. The thermostatic radiator valves may be mechanical or electronic, and in some cases may communicate with external room temperature sensors.

[0071] The outlet of each radiator is connected to the return pipe R by a radiator outlet pipe 22. Between the radiator outlet and the outlet pipe 22, an automatic balancing valve device 10 as described above is provided. The automatic balancing valve device 10 is essentially in the form of a radiator tail, and as shown in Figure 4 is disposed between the radiator outlet and a conventional lockshield valve 32.

[0072] When the building is cold and the heating system is first turned on, all valves are likely to be open, although the setpoint of the thermostatic valves 30 may be set to different temperatures (for example, so that a living room is warmer than a bedroom). Likewise, the water in the flow pipe F is cold and so the valves in the automatic balancing devices 10 will also be open. Water therefore flows freely into all radiators. However, it will be seen that radiators close to the pump will receive a higher flow and will tend to heat up faster. Initially, hot water will flow through the radiator closest to the pump relatively quickly, and this may mean that the temperature of the water flowing through the respective automatic balancing device is relatively high. However, the automatic balancing device reacts quickly to restrict the flow. This will ensure that the flow through the radiator close to the pump is restricted so that more heat from the water is given out to the room, and also that radiators further from the pump receive a share of the heat from the boiler.

[0073] The set point temperature of each device 10 may be adjusted to suit the particular requirements of the central heating system. It is envisaged that all of the devices 10 in a particular system will be set to the same set point temperature, which will depend on the flow temperature required in the system. Boilers will generally operate more efficiently with lower flow temperatures, but the flow temperature does need to be set high enough to adequately heat the building, and higher flow temperatures may be required for example in poorly-insulated buildings with undersized radiators. Figure 5 shows the device 10, in particular showing the back of valve seat 16a. Blind holes 23 are provided in a back surface of the valve seat 16a, so that a pin spanner may be used to turn the valve seat 16a, moving it on its mounting thread so that its longitudinal position along the conduit may be adjusted. This adjusts the set point temperature.

[0074] The device 10 can be retrofitted into the heating system, for example wherein an old radiator tail is removed, and the device 10 is connected to the heating system as a replacement.

[0075] Referring to Figure 6, another embodiment of the device is generally indicated at 200. This embodiment is similar to the one shown in Figures 1 to 5 but the valve 216 is disposed next to the inlet 212a of the conduit 212, and the temperature sensor 214 is disposed next to the outlet 212b of the conduit 212.

[0076] In addition, the device 200 is provided in a separate housing 222 designed to be installed in place of a lockshield valve, rather than being in the form of a radiator tail.

[0077] Two substantially parallel flow passages are formed within a section of the housing 222. A first flow passage 211 connects an outlet of an existing radiator tail 213 of the system to the inlet 212a of the conduit 212. A second flow passage 215 forms the conduit in which the valve is disposed. The wall of the conduit 212 separates the first and second flow passages.

[0078] A first section of the conduit 212 i.e. between the inlet 212a and a central region of the conduit 212 has a smaller diameter or width than a second section of the conduit 212 i.e. between the central region and the outlet 212b of the conduit 212. This forms a space between the wall of the housing 222 and the wall of the conduit 212 which forms the first flow passage 211. The channel or aperture within the conduit 212 of the device 200 forms the second flow passage 215.

[0079] In use, the water from a radiator flows through the existing radiator tail and through the first flow passage 211, through the valve to the second flow passage 215 and then back to the boiler via the return system circuit pipe. As the temperature increases to the set point temperature, the temperature sensor 214 moves the valve 216 to the closed position i.e. the temperature sensor 214 moves the valve member 216b upwards to sit against the valve seat 216a.

[0080] As the temperature decreases from the set point temperature, the temperature sensor 214 moves the valve 216 to the open position i.e. the temperature sensor 214 moves the valve member 216b downwards away from the valve seat 216a.

[0081] In this embodiment, an external handle 230 is provided. The external handle 230 controls the position of a second valve member 232, which can act to close the valve 216 by coming against the valve seat 216a from the side of the valve seat 216a which faces away from the first valve member 216b. In other words, the valve comprises a two-sided valve seat and can be closed either by the automatic temperature controlled valve member on one side (the underside as shown in Figure 6) or by the manual handle controlled valve member on the other side (the upper side as shown in Figure 6). The device 200 shown in Figure 6 can therefore be used to replace a conventional lockshield valve, and may be used to shut of the radiator altogether, for example if it needs to be removed for decorating.

[0082] Overall, the use of these devices allows the central heating system as a whole to work effectively and efficiently. The devices of the invention work together with conventional thermostatic radiator valves (which are installed on the inlets of the radiators) to ensure a dynamically balanced system, which will heat up all rooms quickly to the room temperature set by the thermostatic radiator valves. The automatic balancing valves of the invention ensure that, during the heat-up phase after the system has been off for some time, all radiators in the system receive hot water and all radiators give out heat to rooms, irrespective of the distance of each radiator from the pump. The valve of the invention also ensures a suitable temperature drop across the radiators, and hence a return temperature to the boiler which is much lower than the flow temperature from the boiler. This decreases the cost and energy used up by the system.

[0083] Figure 7 illustrates what typically happens when a central heating system is switched on and hot water rushes into a cold radiator. As is usually the case in the UK, the radiator is connected to the heating system circuit at opposing bottom corners. In Figure 7, the inlet to the radiator is on the bottom left corner and the outlet is on the bottom right corner.

[0084] As can be seen from Figure 7, heat from hot water entering the radiator first spreads along the left-hand side and bottom side of the radiator. These parts are the hottest parts of the radiator and are illustrated in red. The coldest parts of the radiator are illustrated in blue, and are mostly in the right section of the radiator. The heat then slowly spreads along the top side of the radiator, and also upwards from right to left (illustrated in green / yellowish red) until the radiator is evenly heated. However, before the radiator is evenly heater, a significant amount of hot water flows out of the outlet, even when (in this example) most of the top-right region of the radiator is still cold. This is wasteful. A device according to the invention increases the efficiency of the system by restricting the flow of hot water on the outlet, allowing the time for the heat to spread throughout the radiator. This makes more efficient use of the heat in the water which has been heated by the boiler.

[0085] The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Examples

Embodiment Construction

[0046]Referring firstly to Figures 1 to 3, a device for automatically controlling the rate of flow of water out of a radiator 20 in a hydronic central heating system is generally indicated at 10.

[0047]The device 10 comprises a conduit 12, and a temperature sensor 14 and a valve 16 connected to each other and disposed within the conduit 12.

[0048]The conduit 12 is in the form of a radiator tail which is a connector for connecting to an outlet of the radiator, as shown in Figure 1. The radiator tail 12 is a tubular member and can be made from metal. The radiator tail 12 has an inlet 12a at one end and an outlet 12b at the opposite end, as can be more clearly seen in Figures 2 and 3.

[0049]In some embodiments, the inlet 12a of the radiator tail 12 can be connected to the radiator outlet and the outlet 12b of the radiator tail 12 can be connected to a radiator valve such as a lockshield valve. In other embodiments, the valve 16 of the device 10 removes the need for a radiator valve to be ...

Claims

1. An automatic balancing device for controlling the rate of flow of water out of a radiator in a hydronic central heating system, the device comprising: a conduit having an inlet and an outlet, the inlet being in fluid connection with the outlet for allowing flow of water from the inlet to the outlet; a temperature sensor disposed within the conduit for detecting temperature of the water flowing out of the radiator; and a valve connected to the temperature sensor and disposed within the conduit, the valve being movable to a closed or restricted position as the detected water temperature increases to a set point temperature, and being configured to return to an open or relatively unrestricted position as the detected water temperature decreases below the set point temperature.

2. A device as claimed in claim 1, in which the conduit is in a form of a radiator tail, the inlet of the radiator tail being adapted to connect to a radiator outlet and the outlet of the radiator tail being adapted to connect to a radiator valve or return system circuit pipe of the system.

3. A device as claimed in any preceding claim, in which the temperature sensor increases or decreases in length axially along the conduit.

4. A device as claimed in claim 3, in which the temperature sensor increases in length causing the valve to move to the closed or restricted position as the detected water temperature increases to the set point temperature, and in which the temperature sensor decreases in length causing the valve to move to the open or relatively unrestricted position as the detected water temperature decreases.

5. A device as claimed in any preceding claim, in which the temperature sensor is in the form of a wax-filled or fluid-filled capsule.

6. A device as claimed in any preceding claim, in which the temperature sensor is disposed substantially centrally in the conduit, spaced from an inner surface of the conduit, and in which a retaining spacer is provided between the temperature sensor and the conduit to support and retain the temperature sensor in position spaced from the conduit, the retaining spacer for example being in the form of a ring having gaps or apertures to allow water to flow around the temperature sensor, between the temperature sensor and conduit walls.

7. A device as claimed in any preceding claim, in which the valve comprises a valve seat and a linearly-movable valve member.

8. A device as claimed in claim 7, in which the position of the valve seat along the conduit is movable to adjust the set point temperature.

9. A device as claimed in claim 7 or claim 8, in which the temperature sensor moves the valve member to sit against the valve seat in the closed position as the temperature increases to the set point temperature, and in which the temperature sensor moves the valve member away from the valve seat in the open position as the temperature decreases.

10. A device as claimed in any preceding claim, in which the temperature sensor is disposed next to the inlet of the conduit and the valve is disposed next to the outlet of the conduit.

11. A device as claimed in any one of claims 7 to 10, in which the valve seat of the valve is disposed next to the outlet of the conduit and the valve member of the valve is the part of the valve which is connected to the temperature sensor and which moves as the temperature sensor changes in temperature.

12. A device as claimed in any preceding claim, in which a spring biasing the valve to the open position is provided.

13. A device as claimed in claim 12, when dependent on claim 7, in which the spring is disposed between the valve member and the valve seat of the valve, to urge the valve member away from the valve seat.

14. A device as claimed in any preceding claim, in which the valve is adapted to set the temperature of the water flowing out of the radiator.

15. A hydronic central heating system comprising: a boiler having a thermostat for setting the temperature of the water flowing out of the boiler; and two or more radiators, the or each radiator comprising: a thermostatic valve connected to a radiator inlet for detecting the air temperature in a room and controlling the flow of water into the radiator depending on the detected air temperature; and a device as claimed in any preceding claim for detecting the temperature of the water flowing out of the radiator and controlling the flow of water out of the radiator depending on the detected water temperature.

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