WO2022079421A1

WO2022079421A1 - Inhibitor injector and filling loop apparatus with remote operation for a heating system

Info

Publication number: WO2022079421A1
Application number: PCT/GB2021/052626
Authority: WO
Inventors: Christopher Jepp
Original assignee: Christopher Jepp
Priority date: 2020-10-12
Filing date: 2021-10-11
Publication date: 2022-04-21
Also published as: EP4244538A1; GB2601053A; GB202114522D0

Abstract

A filling loop apparatus is provided to deliver a charge of water from a mains supply to a heating circuit in a space and/or water heating system. The filling loop incorporates an attended valve comprising a spool (6) which is arranged to deliver the charge of water from the mains when actuated but to provide an air gap through which water from the heating circuit will drain so that no water from the heating circuit can return to the mains supply. The filling loop apparatus has includes a canister (21) of inhibitor agent whereby inhibitor is injected into the charge of water whenever the heating circuit is charged, in proportion to the volume of water charge delivered. The apparatus has a remote actuator (117) connected to the attended valve whereby the attended valve can be actuated in response to a command from a remote control station communicating with the apparatus via a wide area network.

Description

INHIBITOR INJECTOR AND FILLING LOOP APPARATUS WITH REMOTE OPERATION FOR A HEATING SYSTEM

Technical Field

[0001] The present invention relates to an inhibitor injector and a filling apparatus for a sealed central heating system, particularly a pressurised sealed central heating system. The applicant is the inventor of the filling loop device described in GB2527621. Such devices are used to charge a pressurised sealed central heating system when the system is being commissioned or when leakage causes the water in the system to become depleted. The device of GB2527621 allows the filling loop to be permanently connected to the mains supply while ensuring that the water in the system cannot leak back into the mains supply. The device further facilitates recharging a depleted system by the system operator, commonly the householder, without the risk of over charging and damaging the system.

[0002] Heating systems using water as working fluid should include a charge of an inhibitor in to prevent fouling from sludge and consequent significant deterioration in performance and system durability. The inhibitor is commonly a mixture of potassium tetraborate tetrahydrate, disodium molybdate, sodium nitrate and 2,2',2”-nitrilotriethano. Whenever a system loses water it loses a proportion of the inhibitor dissolved into the water. If a system is leaking badly enough the concentration of inhibitor in the system can fall to the point where it ceases to be effective. Systems recharged by the operator are unlikely to record the frequency of recharge and consequently the absence of inhibitor is unlikely to be noted or repaired until the system suffers a severe fault requiring attendance by a heating engineer, who may simply renew the inhibitor charge as part of the repair process. The build-up of sludge during inhibitor deficient operation will result in many systems operating inefficiently, increasing their carbon footprint. The reduced system durability will result in increased carbon footprint as components such as the system pump must be replaced, and there is of course downtime inconvenience and expense to the operator. Prior Art

[0003] GB2527621 describes a filling loop device which as adapted to be permanently connected between the mains supply of water and the heating circuit of a pressurised sealed central heating system.

[0004] Conventionally introducing inhibitor to a sealed pressurised heating system involves the following steps: (1) depressurise the system (2) open a radiator bleed valve and completely remove the bleed nipple from the radiator bleed port (3) insert an adapter nozzle on the end of a feed tube into the bleed port (4) open the shield valve of the radiator (5) discharge the inhibitor from a delivery container into the radiator through the feed tube. The delivery container is usually adapted to be filled with a charge of inhibitor sealed and compressed with air from a manual pump. (6) when the charge has been delivered, close the shield valve (7) remove the adapter nozzle (8) replace the bleed valve (10) re-pressurise the system (11) check the radiator for leaks. This process is evidently labour intensive and not something the ordinary user is willing or able to undertake.

[0005] It is an object of the present invention to reduce the risk of a sealed central heating system using a filling loop device similar to the device of GB2527621 , becoming inhibitor deficient.

Summary of Invention

[0006] According to the present invention there is provided an inhibitor injector and filling loop apparatus for a heating system wherein the filling loop apparatus comprises: a housing defining a water passage having, an inlet port connectable to a water supply and an outlet port connectable to a heating system water circuit; and a valve interposed in the fluid passage between the inlet port and the outlet port, said valve biased to a normally closed condition to shut off water flow through the fluid passage in either direction and operable by an actuator to an open condition to permit water to flow from the inlet port to the outlet port to charge the system; wherein operation of the actuator causes inhibitor to be drawn from a reservoir of inhibitor through an inhibitor passage into the outlet port whereby inhibitor can be injected into the water supply to the heating system water circuit while the valve is in the open condition.

[ooo7] Preferably the valve is a spool valve biased by a spring to the closed condition.

Preferably the spool includes a through passage which communicates the inlet port and the outlet port in the open condition and a discharge port which communicates the outlet port and a drain port in the closed condition. This serves to ensure that water from the heating circuit cannot drain back into and contaminate the mains water supply.

[ooo8] In an embodiment the valve actuator may be a press button external to the housing for manual actuation. The spring bias ensures that the valve can only be opened when attended by an operator.

[ooo9] The passage may be provided through a stem of the press button. The inhibitor passage may be closed when the press button is unloaded. The closure may be effected by a spring biased inhibitor valve arranged to keep the inhibitor passage closed until the press button has moved the spool to the open condition. Further movement of the press button and spool overcomes the bias of the inhibitor valve to open the inhibitor passage from the chamber into the through passage communicating the inlet port to the outlet port. Preferably the reservoir is provided by a replaceable canister containing a charge of inhibitor. The canister may comprise a collapsible bladder containing the inhibitor surrounded by the substantially rigid container. The bladder may be arranged to discharge inhibitor through a one way valve into the inhibitor passage. The bladder may be subject to compression in order to overcome the pressure of water in the through passage. Compression may be provided by a compressed gas supply from a gas cartridge. In a variant of the apparatus the bladder may be provided by an elastomer balloon such that the energy stored in the bladder when it is charged and expanded during manufacture is sufficient to pressurise the inhibitor and obviate the gas cartridge. In a further variant of the apparatus a throttle such as a venturi may be provided in the through passage. The venturi is designed to reduce the pressure of the water flowing through the through passage below the pressure of inhibitor in the canister. In another alternative variant a compressed charge of air may be delivered to the space between the container and the bladder by a manually operable pump. Any combination of these features may be used to ensure that inhibitor flows from the canister into the inflowing charge of water. For example an elastomeric bladder may be used to increase the pressure of the inhibitor while a venturi reduces the water pressure in the passage. Preferably the canister is made of card to be recyclable or is made of a more durable metal or plastics material adapted to be reused by the insertion of a replacement bladder filled with inhibitor.

According to second aspect of the present invention there is provided a filling loop device for a pressurized heating system comprising: means defining a fluid passage having, an inlet port connectable to a fluid supply and an outlet port connectable to a heating system fluid circuit; an attended valve interposed in the passage between the inlet port and the outlet port, said attended valve biased to a normally closed condition to shut off fluid flow through the fluid passage in either direction when unattended, and operable to an open condition to permit fluid to flow from the inlet port to the outlet port; a remote actuator assembly, said actuator assembly comprising; a communications network interface communicable with a telecommunications network and a controller; and a servomotor capable of driving the attended valve from the closed condition to the open condition in response to the controller; whereby the attended valve can be driven to the open condition in response to a command transmitted over the network.

[0010] Preferably the filling loop device includes a governor assembly arranged to stop the flow of water into the pressurized heating system when the pressure on the downstream side of the device reaches a predetermined pressure.

[0011] The filling loop device may include means responsive to the pressure of the water downstream of the device to communicate the below-pressure condition to the controller. Preferably the controller will communicate the below-pressure condition to a remote, networked, monitoring station.

[0012] The monitoring station may communicate with the network by any of a range of conventional and developing telecommunications networks and protocols, including wireless technologies such as WiFi®, Bluetooth® or ZigBee®. The device may be mains powered and may communicate over mains and service power lines using known technology, or via a LAN and or a gateway through the internet. In its most basic form the filling loop device enables a remote operator to respond to the report of a faulty boiler by sending the actuation command to the attended valve thereby recharging the system to restore function, without requiring the delay and expense of an attending heating engineer.

[0013] By including a mechanism to report the downstream pressure condition to a monitoring station a fault condition may be detected, reported and acted on before the system owner is aware of a problem. Ongoing monitoring may also reveal the presence of a persistent fault condition requiring the attendance of an engineer.

[0014] The attended valve may having a casing with a fluid passage communicating an inlet port, an outlet port and, a spool chamber. A spool is slidably housed in the spool chamber, said spool including a through passage capable of communicating the inlet port and outlet port for fluid flow therebetween, and bias means to urge the spool so that a lower part of the spool obstructs the fluid passage. A drain passage is preferably formed in the lower part of the spool communicable between the outlet port and a drain port formed in the spool chamber. This arrangement ensures that none of the water in the pressurised heating system can leak back passed the filling loop into the mains water supply.

[0015] The fluid passage may be provided by a length of pipe, flexible hose or via a channel in a mono-block. The inlet and outlet ports may be provided by any conventional coupling including at least: threaded BSP and compression couplings.

[0016] The attended valve is a valve which is biased to the closed condition and operable by an actuator to switch to the open condition. Consequently on releasing the actuator the valve closes preventing water flow from the mains supply to the heating circuit.

[0017] To ensure there is no backflow from the boiler circuit to the mains water, a one way or check valve is connected such that flow from the inlet to the outlet connector is allowed while the reverse flow is prevented. Single check valves may be vulnerable to reverse flow leakage to prevent which a double check valve may be provided. [0018] A second isolation valve may be connected to the check valve.

[0019] A check valve and an isolation valve may be provided in the same housing.

[0020] In some embodiments the device comprises, connected in order along the flow pathway: a 15mm inlet compression to 8mm ball valve, an 8mm push button water valve, a 15mm to 8mm adapter, a 15mm flexible filling link comprising a metal braided hose and a 15mm double check ball valve.

Brief Description

[0021] Embodiments of an inhibitor injector and filling loop apparatus for a heating system, constructed in accordance with the present invention, will now be described, by way of example only, with reference to the accompanying figures, wherein: figure 1 is a south east isometric view of the device showing assembly of a canister to the filling loop device; figure 2 is a sectional front elevation of the device of figure 1 ; figure 3 is a south east isometric view of the assembled device in the off condition; figure 4 is a front sectional elevation of the device of figure 3 in the off condition; figure 5 is a sectional front view of the device of figure 4 in the open or charging condition; figure 6 is a front elevation of a second embodiment; figure 7 is a front sectional elevation of the second embodiment; figure 7.1 is a variant of the second embodiment; figure 8 is an isometric view of part a heating system; figure 9 is a side sectional front elevation of a filling loop device; figure 10 is a SE isometric view of the filling device of figure 2; and figure 11 is a high level circuit diagram of the filling loop device.

Detailed Description of Figures

[0022] The apparatus comprises a housing 1 defining a water passage 2 having an inlet side 2.1 communicating with an inlet port 3 and an outlet side 2.2 communicating with an outlet port 4. The inlet port 3 has a female thread for connection to a mains water supply. An isolation valve (not shown) will usually be provided upstream of the inlet port or may be integrated into the inlet passage side 2.1. The outlet port 2.2 is adapted for connection with the water circuit of a pressurised sealed heating system (not shown) in this example by means of a female thread. In variants of the apparatus the adaption for connection may be a male or female compression coupling or solder coupling such as is well known in the technical field. One or more one way valves may be installed downstream of the apparatus, or integrated into the outlet passage 2.2 to deter water from the heating circuit returning into the mains supply.

[0023] A spool valve chamber 5 is provided in the housing extending perpendicular to the through passage 2 to divide the through passage into the inlet side 2.1 and the outlet side 2.2. A spool 6 is slidably displaceable in the spool chamber 5 and provides an open bore 7 capable of communicating the inlet side 2.1 of the through passage with the outlet side 2.2 of the through passage 2 when the spool is displace to an open condition as shown in figure 5. The spool further provides a closed bore 8 which only provides a passage communicating the outlet side passage 2.2 to a drain port 9 formed in a base 10 of the spool chamber to discharge. The drain port 9 is conveniently provided with a nipple 11 whereby a drain pipe or hose can be connected either permanently or temporarily to facilitate draining the system to the exterior of the property or to a wastewater drain.

[0024] The spool 6 is biased by a compression spring 12 which may be provided in the bottom of the spool chamber 5 to act between the housing and the spool and bias the spool to the closed condition.

[0025] A valve stem 13 is rigidly secured into a through hole 15 in the top of the spool 6 and extends through a sealed aperture 14 in the top of the housing 1. The valve stem allows the spool 6 to be displaced against the bias spring 12 to bring the open bore 7 into alignment with the inlet and outlet sides 2.1 and 2.2 of the through passage 2 and allow water to flow through the apparatus to charge the heating system.

[0026] The valve stem 13 is formed as a hollow tube to slidably receive an inhibitor injection tube 16. The injector tube 16 is biased to a closed condition shown in figure 4 by a compression spring 17 which acts between a flange 18 forming a top part of the valve stem 13 and a cup 19. The injector tube 16 terminates in a one way valve 20, such as a Schrader valve which projects up into the axis of the cup 19. [0027] A canister 21 consists of a hollow cylinder 22 closed by a top 23 and a bottom 24. The canister contains a bladder 25 formed from a flexible polymer to contain a charge of inhibitor 26. The bottom 24 incorporates a closure 27 which captures an open mouth of the biadder 25 in a cooperating formation 28 such as a screw thread. The closure includes an axially located threaded opening 29 to receive the projecting male thread of the Schrader valve 20. The Schrader valve 20 is cooperable with a similar valve (not shown) in the opening 29 causing each valve to open and permit the flow of inhibitor into the injector tube 16.

[0028] In order to propel inhibitor into the water flow in the through passage against the pressure of the water in the through passage, a gas cartridge 30 containing a substantially inert compressed gas charge is connected through a port 31 located in the top 23 of the canister 21. Such compressed gas cartridges are commonly available containing compressed gases such as carbon dioxide or nitrogen for various purposes. A fitting to pierce the nozzle of the gas cartridge is provided in the port 31 as is well known in other applications such as tyre inflators. The compressed gas fills the space between the bladder and the inside of the cylinder raising the pressure of the inhibitor above the pressure of the inflowing water in the through passage.

[0029] Operation of the apparatus requires the canister to be pressed down thereby displacing the valve stem 13 against the bias spring 12. When the valve stem 13 is fully depressed the canister is pressed with sufficient force to overcome the spring force of the spring 17. Spring 17 is selected to require a greater spring force to deform than bias spring 12. When the applied force exceeds the spring force 17 the injector tube 16 is displaced down relative to the valve stem 13 as shown in figure 5. This opens valve ports 32 formed in the bottom of the injector tube 16 allowing pressurised inhibitor to flow from the bladder 25 through the valve 20 and through the ports 32 into the water flowing into the heating system circuit. When the heating system circuit is charged, usually indicated via a pressure gauge in the system reaching a predetermined pressure such as 2 bar, the user removes the load from the canister. Springs 12 and 13 return the injector tube to its up and closed position relative to the valve stem and return the valve stem and associated spool to the closed condition shown in figure 4. [0030] Thus whenever the system is charged with water due to water loss it is simultaneously charged with inhibitor in proportion to the loss of water and inhibitor.

[0031] The canister can readily be replaced when depleted simply by unscrewing the canister from the cup and replacing it with a fully charged canister a process readily undertaken by an unskilled user. The canister has been designed with recycling in mind such that the closure can be removed, the used bladder refilled, or replaced and refilled, and the recycled canister resold with a new charged gas cartridge.

[0032] The canister may readily indicate when depletion occurs simply by the provision of a transparent window in the container wall extending between the top and bottom, allowing a view of the bladder, or by making the whole canister of transparent material, eg transparent plastics.

[0033] Figures 6 and 7 show a second embodiment of the inhibitor injector and filling loop apparatus in which a venturi 33 is installed downstream of the spool valve chamber 5. The venturi 33 provides a reduced diameter passage for water flow which is designed to reduce the pressure of water when it flows through the spool valve from the mains supply to below atmospheric pressure. A siphon tube 34 has a venturi end intruding into the axis of a venturi passage, where the water pressure will be least. The siphon tube extends from the venturi end through a body 35 of the venturi 33 to an downstream port of a manually operable shut off valve 37. An upstream port of the shut of valve 37 is provided with a coupling 38. Coupling 38 may be threaded or a bayonet fitting.

[0034] The canister 21 comprises a rigid cylindrical outer shell 22 and has a rigid lower end cap 41 and a rigid upper end cap 42. The upper end cap 42 includes an outer annular part 43 and an inner annular part 44 which are secured together to retain the open mouth of the flexible bladder 25. The bladder 25 is thus suspended from the upper end cap and will when supplied be filled with a solution of inhibitor. A cylindrical tubular coupling 45 extends axially through the inner annular part and carries a canister siphon tube 46 which depends to an opening just above the bottom of the bladder and canister. The coupling 46 has a threaded external end 47 adapted to screw into the threaded coupling 38. When supplied the external end 47 may be closed by a simple screw cap or bung to prevent leakage of the inhibitor contents. [0035] In use the canister of inhibitor is applied to the apparatus by first closing the shut off valve 37 to prevent the water in the heating system leaking out. The cap is removed from the coupling 46 and the end 47 is screwed into the coupling 38 forming a water tight seal. The coupling may include seals such as “O” ring seals as is well known to the person skilled in the art to ensure a water tight seal. The valve 38 is then opened. The shell provides a protective casing for the bladder and facilitates handling and installation. The shell includes a vent 48 which allows the region between the shell and the bladder to be maintained at atmospheric pressure.

[0036] In use whenever a valve button 49 is depressed the spool 6 is displaced down against the bias spring to allow water to flow into the heating circuit. The flowing water charge passes through the venturi such that the water pressure drops below atmospheric pressure. The inhibitor in the bladder is at atmospheric pressure and is therefore urged to discharge into the inflowing water charge. The volume of inhibitor injected is therefore proportional to the delivered water charge and appropriate design of the size of the siphon tube and the venturi throat dimensions can ensure and appropriate proportion of inhibitor is injected to maintain an optimum inhibitor concentration in the heating circuit.

[0037] Figure 7.1 shows a variant of the second embodiment in which the canister is sealed obviating the port 48. To induce a pressure differential a conduit 50 is provided between a port 51 upstream of the venturi throat and a port 52 in the canister. The space between the canister and the bladder therefore fills with stationary water at the relatively high pressure upstream of the canister which will always be at a pressure higher than the water flowing through the venturi. This creates a pressure differential between the inhibitor in the bladder inside the canister and the water flowing through the venturi which causes inhibitor to flow through the siphon into the venturi.

[0038] Figure 8 shows a boiler or furnace 101 connected to the pipe circuit 102.0, 102.1 of a pressurised space heating circuit where pipe 102.0 is the water feed pipe and pipe 102.1 is the return pipe. A pipe spur 102.2 is connected to the feed pipe 102.0 to allow the circuit to be charged up to mains supply pressure from a mains supply pipe 103. The spur may be placed on either the feed or supply. [0039] The mains supply 103 is connected to the spur 102.2 via a check valve 104, a pipe 105 and check valve 106. Conventionally pipe 105 is a flexible hose which is removed after charging. The check valves 104 and 106 to minimise the risk of heating circuit water leaking back into the mains supply during charging. In the system of the present invention the pipe 105 is permanently installed and may be inflexible.

[0040] A filling device 108 is installed in the pipe 105 between the check valves 104 and 106. The filling device comprises an attended valve essentially identical to the applicant’s attended valve as disclosed in GB2527621. The attended valve comprises a casing 109 providing an inlet port 110 with internal threaded coupling and an outlet port 111 with an internal threaded coupling. The inlet and outlet ports communicate with a cylindrical spool chamber 112 oriented perpendicular to the inlet and outlet passage so that a spool 113 can slide along the axis of the spool chamber. The spool is biased to a closed condition by the action of a coil spring (not shown) received into a spring chamber 114 in the bottom of the spool chamber. The spring presses the spool up in the drawings. When biased to the closed condition the bottom part of the spool presents an open discharge passage 113.1 to only the outlet passage 111 and the spring chamber. The spring chamber communicates with a drain passage 115 so that any water leaking back passed the check valve 106 is discharged from the system. A drain nipple 116 may be provided in communication with the drain passage 115 to connect with a drain tube (not shown) to discharge leaking water safely, for example to a waste water pipe or an overflow.

[0041] The spool 113 can be depressed by means of a press button 113.2 (49) projecting from the top of the casing 109. When the spool is depressed against the action of the spring bias (as shown in Figure 9) a communicating passage 117 in the spool is brought into alignment with the inlet and outlet passages 110 and 111 allowing mains water to flow into the pressurised heating circuit 102.

[0042] A remote actuator assembly 117 is coupled to the attended valve 108 or the spool of the first or second embodiments . The remote actuator assembly 117 includes a casing 118 having a harness 119 whereby the actuator assembly 117 can be coupled to the attended valve 108. The casing 118 houses a servo motor 120 arranged to engage the press button 113.2 so that only when the actuator motor is powered the press button is depressed.

[0043] The actuator motor is driven in response to a command emitted by a control circuit 121 mounted in the casing. The control circuit 121 includes a telecommunications network interface 122. The interface 122 allows command signals to be received from a remote control station. It is envisioned that the interface may be connected to the internet or another wide area network. Connection to the internet may be via WiFi ®, using the premises WiFi network in known manner. Alternative methods of connection may include via mains circuit signalling

[0044] The interface may also receive a pressure signal from a pressure sensor 107 arranged to sense the pressure in the heating circuit. The interface may communicate the pressure sensed to the remote control station.

[0045] The filling device may also include a governor assembly to limit the maximum pressure of water delivered to the pressurised heating circuit to a predetermined safe maximum. Known pressure governors may simply be added to govern the water flow upstream or downstream of the filling device.

[0046] By means of the present invention an under pressure or over pressure fault condition in the heating circuit can be notified to a remote control station and/or the system owner. The control station can then remotely command the actuation of the valve 108 to recharge the system without the attendance of an engineer, thereby at least temporarily repairing the system. If the fault condition is persistently repeated this may be noted by the control station which will recognise a more pernicious fault requiring investigation and repair before the boiler sustains more serious damage.

[0047] The remote control actuator 117 can be applied to the attended valve of the first second or third embodiments in order to that inhibitor be injected during remotely commanded operation of the attended valve 108.

Claims

Claims An inhibitor injector and filling loop apparatus for a heating system wherein the filling loop apparatus comprises: a housing defining a water passage having, an inlet port connectable to a water supply and an outlet port connectable to a heating system water circuit; and an attended valve interposed in the fluid passage between the inlet port and the outlet port, said valve biased to a normally closed condition to shut off water flow through the fluid through passage in either direction and operable by an actuator to an open condition to permit water to flow from the inlet port to the outlet port to deliver a charge of water to the system; wherein operation of the actuator causes a reservoir of inhibitor to deliver inhibitor to the water charge. Apparatus according to claim 1 wherein the volume of inhibitor delivered is proportional to the volume of the water charge. Apparatus according to claim 1 or claim 2 wherein the chamber is provided by a replaceable canister containing a reservoir of inhibitor. Apparatus according to claim 3 wherein the canister comprises a collapsible bladder containing the inhibitor surrounded by a substantially rigid container. Apparatus according to claim 4 wherein the bladder is arranged to discharge inhibitor through a shut off valve into an inhibitor passage communicating with through passage. Apparatus according to claim 4 or claim 5 wherein a pressure difference is induced between the inhibitor in the bladder and the water charge supplied to the heating system. Apparatus according to claim 6 wherein the pressure difference is induced by the provision of a venturi between the attended valve and the outlet port to reduce the water pressure in the water charge downstream of the attended valve, whereby a siphon acting between the throat of the venturi and the inhibitor in the bladder provides a passage whereby inhibitor is siphoned from the bladder into the water charge. Apparatus according to claim 7 having a shut off valve between the canister and the venturi to facilitate exchange of the canister without substantial leakage of the system water. Apparatus according to any one of claims 4 to 8 wherein the canister has a vent to keep the space between the canister and the bladder at atmospheric pressure. Apparatus according to any one of claims 4 to 8 wherein the canister is sealed and communicates via a conduit with a port upstream of the venturi throat whereby the canister interior and bladder are brought to a high upstream pressure. Apparatus according to any one of claims 5 to 8 wherein the canister chamber can be pressurised from a compressed gas cylinder and said shut off valve is operable to open in response to the actuation of the attended valve in order to discharge inhibitor from the bladder to the water charge. Apparatus according to any one of the preceding claims having a remote actuator connected to the attended valve whereby the attended valve can be operated in response to a command sent from a remote control station. Apparatus according to claim 12 wherein the remote actuator is a servo motor arranged to be capable of applying load to the attended valve only when powered. Apparatus according to claim 12 or claim 13 wherein the remote actuator is responsive to commands received from an interface with the remote control station, wherein the interface communicates with the remote control station via a wide area network. Apparatus according to any one of claims 12 to 14 wherein a pressure sensor is arranged to sense the pressure of water in the heating circuit, said pressure being communicated to the interface which is responsive to communicate the pressure to the control centre.