GB2338542A

GB2338542A - A domestic boiler for space heating and domestic water featuring a detachable sub-assembly for easy installation

Info

Publication number: GB2338542A
Application number: GB9813053A
Authority: GB
Inventors: John Frederick Michae Bosworth
Original assignee: Heating World Group Ltd
Current assignee: Heating World Group Ltd
Priority date: 1998-06-18
Filing date: 1998-06-18
Publication date: 1999-12-22
Anticipated expiration: 2018-06-18
Also published as: GB2338542B; GB9813053D0

Abstract

A domestic boiler for producing primary hot water for space (central) heating and secondary water for domestic use, consisting of a boiler vessel 11 and burner unit 12 and a sub-assembly 16 including a heat exchanger 20, a motorised valve 21 to direct primary hot water through the central heating circuit and the heat exchanger and control means for at least the valve. The pipework has threaded connections (27,29, fig.2) to permit the components of the sub-assembly to connect to the boiler vessel and to the domestic pipes (26, 30 and 34, fig.2) for space heating and also the hot and cold water supply pipes. This enables the sub-assembly to be detached as a unit from the boiler assembly following disconnection of said threaded connections. The sub-assembly, boiler vessel and burner unit can be mounted separately on a back plate 10. The sub-assembly may also include a central heating circulation pump, mixing valve (for output of heat exchanger), expansion chamber for primary and/or secondary water and a flow sensing valve for secondary water through the heat exchanger.

Description

Ref 11394sp 2338542 DOMESTIC BOILER This invention relates to a domestic

boiler, for producing primary hot water for space heating and also secondary hot water for domestic use.

A known form of domestic boiler which provides primary water for space (central) heating and also rapid on-demand domestic hot water within one packaged unit has become increasingly popular on account of certain advantages regarding the economy of size, initial purchase costs and installation costs. In addition, there is no need to provide a separate hot water storage tank. Such a boiler has commonly become known as, and will hereinafter be referred to as, a "combi-unit".

Further to assist with the reduction of space used in a dwelling by a combi-unit, most are constructed for mounting on a wall, using a socalled "balanced-flue" system for the discharge of the products of combustion of the fuel - which is either a hydro-carbon oil or gas. A typical wall-mounted combi- unit has a-steel back-plate on which all of the various components of the boiler are mounted. Installation requires the provision of the various pipes to connect to the central heating circuit, the cold water supply and the domestic hot water feed as well as a flue pipe through the wall. Then, the entire boiler (but with its casing removed) must be lifted into position and attached to the wall by suitable fixings. Thereafter, the pipework connections may be completed, the electrical and fuel services connected and the boiler commissioned.

A combi-unit of the kind described above is relatively heavy and its mounting on a wall can therefore be difficult. In any event, current EU legislation limits the maximum weight which may be lifted by one person in the 1 1 _) Ref 113945P course of employment and many combi-units exceed that weight which may be lifted. Consequently, it may be necessary for an installer of a combi- unit to disassemble the manufactured unit to remove various components in order to reduce the weight of the unit to an acceptable level. In the alternative, it may be necessary to employ two people merely for the purpose of lifting the combi-unit, at the time of installation.

A further disadvantage of a combi-unit is that it is more complex than a conventional, simple domestic hot water boiler. For example, a combi-unit requires a motorised valve together with flow sensors in order to detect when secondary hot water for domestic purposes is required, and then to divert the output of the boiler to a heat-exchanger which provides the domestic hot water. The servicing of a combi-unit is thus not as straightforward as with a conventional boiler and the repair of an installed combi-unit, in the event of a break-down, is also more difficult.

In an attempt to address the above mentioned disadvantages of a combiunit, the present invention provides a domestic boiler for producing primary hot water for space heating and also secondary hot water for domestic use, which boiler comprises a boiler assembly adapted for mounting to a surface and including a boiler vessel for producing the primary hot water and a burner unit, and a sub-assembly including a heat-exchanger for heating the secondary hot water from the primary hot water supplied by the boiler vessel, a motorised valve operable to direct the primary hot water through at least one of a domestic space heating circuit and the heat-exchanger, control means for at least the motorised valve, and pipe-work provided with threaded connections to permit the Ref 11394sp components of the sub-assembly to be connected to the boiler vessel and to the domestic pipes for space heating, domestic hot water, and a cold water supply, the sub-assembly being removeable as a unit from the boiler assembly following disconnection of said threaded connections.

A domestic boiler of this invention is a form of combi-unit as described above, wherein the extra components required for a combi-unit.(as compared to a conventional boiler) are readily separable from a burner assembly. At the time of installation, this permits a significant reduction in the weight of the boiler, merely by removing the sub- assembly. Moreover, should there be a malfunction in the part of the combi-unit which distinguishes the unit from a conventional boiler, the entire sub-assembly may be removed and replaced by another, so permitting a rapid and simple on-site repair. Of course, the removed malfunctioning unit may subsequently be repaired, if appropriate, in a remote workshop.

Further to reduce the weight of the boiler assembly and also to facilitate repair in the event of a breakdown, it is preferred that the sub-assembly also includes a hot water circulation pump which in operation causes the primary hot water to circulate around a connected space (central) heating circuit. Moreover, the sub-assembly may include a mixing valve for mixing the output of the heatexchanger with cold water, to permit control of the temperature of the secondary hot water supply to the domestic hot water system. Such a mixing valve may be pre-set to a required output temperature, and thereafter function automatically depending upon the sensed temperature of the hot water supplied to the domestic hot water system.

Ref 11394sp A combi-unit is normally installed without loft-mounted feeder tanks; thus, the central heating circuit and the secondary hot water both operate at mains water pressure. For such a system, the sub-assembly preferably includes an expansion chamber for the primary hot water, and also a further expansion chamber, for the secondary hot water. These expansion chambers will thus be removed from the boiler assembly, on removing the sub-assembly.

As with a known form of combi-unit, the boiler assembly preferably is provided with a back-plate intended for direct mounting to a wall of a domestic dwelling. In such a case, the sub-assembly is preferably mounted directly on the back-plate, so that once the boiler assembly has been mounted on a wall, it is a relatively simple matter then to connect the sub-assembiy to the boiler assembly.

For example, the backplate may have a shelf or other abutment on to or against which the sub-assembly may be lifted before slid home to its final position adjacent the boiler assembly. Interengaging pegs and holes may be provided on the two assemblies, to locate and hold the sub-assembly in its final position.

Commissioning would be completed by making the required pipework connections both to the boiler itself and to the central heating system and domestic hot water feed and supply pipes as well as the electrical and fuel services. This may be accomplished relatively quickly and easily, even in confined places.

By way of example only, on specific embodiment of combi-unit constructed and arranged in accordance with the present invention will now be Ref 11394sp described in detail, reference being made to the accompanying drawings, in which:

Figure 1 is a perspective view from one side of the embodiment of combi unit, with the casing removed., Figure 2 is a perspective view from above of the right-hand part of the combi-unit of Figure 1 - Figure 3 is a further view from above of the right-hand part of the combi unit of Figure 1, but with the sub-assembly in the course of removal, Figure 4 is a perspective view from below, of the combi-unit of Figure 1. 1 Figures 4A and 413 are detailed views on parts of the boiler shown in Figure 4, Figure 5 is a perspective view of the boiler assembly and the sub assembly, separated,. and Figure 6 shows diagrammatically a combi-unit of this invention.

The assembled embodiment of combi-unit shown in Figures 1, 2 and 4 comprises a back-plate 10 on which all of the various boiler components are mounted, directly or indirectly. A boiler vessel 11 is directly mounted on the back-piate and therebeiow is provided a burner unit 12 together with controls 13.

The burner unit 12 includes a blower 14 which pumps air into the combustion chamber of the boiler vessel 11 and also a fuel oil feed arrangement which supplies a mist of fuel oil into the combustion chamber, for burning with the air supplied by the blower 14. The controls 13 include an ignition circuit to ignite the fuel oil as well as a monitoring device to ensure combustion continues Ref 11394sp during operation. These components are all entirely conventional and form no part of the present invention.

The combiunit includes a sub-assembly 16 which is slidably mounted on the back-plate 10 so that it may be slid sideways and then lifted away from the boiler vessel 11. Alternatively, the sub-assembly could be arranged for sliding movement upwards or downwards before being lifted away, or could simply be lifted away without initial sliding movement. The sub-assembly 16 is locked in its fully mounted position to the boiler vessel 11 by means of a screw 17 (Figure 4A) having a winged head and which passes through a bracket 18 provided on the sub-assembly 16 and into a threaded bore in the boiler vessel. Removal of the screw 17 allows the sub-assembly to be moved laterally to the right, as shown by arrow A (Figure 3) provided the other connections have been freed, as will be described below.

The sub-assembly 16 includes a plate heat-exchanger 20, a three-port motorised valve 21, a mixing valve 22 for domestic hot water and a circulation pump 23, for primary hot water which is to be passed through the central heating circuit. Also forming part of the sub-assembly 16 is a primary expansion chamber 24, for the primary hot water supplied by the boiler vessel and for circulation through the central heating circuit, and a secondary expansion chamber 25, for the domestic hot water supply.

The above described components of the sub-assernbly 16 are connected by pipes, arranged to give the required functionality. In particular, a central heating return pipe 26 is coupled to the boiler vessel 11 by a screw-threaded union 27 that return pipe 26 also being coupled to a return pipe 28 from the Ref 11394sp plate heat-exchanger 20. The output from the boiler vessel 11 connected by threaded union 29 and pipe through the central heating circulation pump 23 to the three port motorised valve 21, one output port of the valve 21 being coupled to a central heating supply pipe 30 and the other port to the input of plate heatexchanger 20, through pipe 31.

A cold water supply pipe 32 is connected both to the input 33 of the heatexchanger 20 and to the mixing valve 22. The output of the heatexchanger 20 is also taken to the mixing valve 22, the output of the valve feeding pipe 34 which is connected to the domestic hot water supply system of a dwelling.

Above the back-plate 10, the four pipes 26, 30, 32 and 34 leading upwardly from the sub-assembly 16 are connected by screw-threaded unions (not shown) to the corresponding pipes of a domestic plumbing installation, to permit primary hot water to be supplied through the central heating circuit and secondary hot water to the domestic hot water supply, with mains pressure water being fed to the cold water supply pipe 32.

A flow-sensing switch 36 is provided on the cold water input pipe to the plate heat-exchanger 20, which switch is operated whenever water is drawn from the domestic hot water system. This switch then triggers the motorised valve 21, to change over from supplying the primary hot water to the domestic heating circuit, to supplying the primary hot water to the plate heat-exchanger 20, whereby the output of the boiler vessel is directed solely to the heatexchanger 20 and thus to provide the required domestic hot water. The electrical wiring for the flow switch 36, the circulation pump 23 and the motorised valve 21, along with any temperature detectors which may be required, are Ref 11394sp taken to one part 37 of an electrical connector 38, provided below the sub assembly 16. The other part of that connector is coupled to the main control system 13 of the boiler, as a whole.

It will be appreciated that the boiler is installed by separating the sub assembly 16 from the back-plate 10, as illustrated in Figures 3 and 5, by undoing the two unions 27, 29 on the side of the boiler vessel 11. Then, the back-plate 10 is mounted on a wall to connect to a flue pipe provided through that wall. The sub-assembly 16 is moved into position adjacent the boiler vessel 11 and the unions 27, 29 tightened to connect the corresponding pipes to the boiler vessel. Moreover, the unions on the four pipes 26, 30, 32 and 34 from the sub-assembly are connected to the corresponding pipes of the domestic installation and the electrical connector 38 below the sub-assembly is coupled.

Finally, the screw 17 is inserted to lock the sub-assembly in position.

Commissioning of the boiler may then continue in the usual way.

Subsequently, should any component of the sub-assembly 16 require servicing or replacement, it is a relatively easy matter to remove the sub assembly 16. In order to minimise the time during which the boiler is out of commission, that sub-assembly may be replaced by another fullyfunctioning unit, with the non-functioning unit being taken away to a workshop for repair.

Figure 6 illustrates diagrammatically the combi-unit boiler described above, with the sub-assembly 16 shown in long chain lines. Like reference numbers are used to indicate like parts, with those described above with reference to Figures 1 to 5.

Ref 11394sp i 1 -g-

Claims

1 A domestic boiler for producing primary hot water for space heating and also secondary hot water for domestic use, which boiler comprises a boiler assembly adapted for mounting to a surface and including a boiler vessel for producing the primary hot water and a burner unit, and a sub-assembly including a heat-exchanger for heating the secondary hot water from the primary hot water supplied by the boiler vessel, a motorised valve operable to direct the primary hot water through at least one of a domestic space heating circuit and the heatexchanger, control means for, at least the motorised valve, and pipe-work provided with threaded connections to permit the components of the subassembly to be connected to the boiler vessel and to the domestic pipes for space heating, domestic hot water, and a cold water supply, the sub-assembly being removeable as a unit from the boiler assembly following disconnection of said threaded connections.

2. A domestic boiler as claimed in claim 1, wherein the sub-assembly further includes a space heating hot water circulation pump to cause the primary hot water to circulate around a connected space heating circuit.

3. A domestic boiler as claimed in claim 1 or claim 2, wherein the subassembly further include a mixing valve for mixing the output of the heat- exchanger with cold water to control the temperature of the secondary hot water supplied to the domestic hot water system.

4. A domestic boiler as claimed in any of the preceding claims, wherein the sub-assembly further includes an expansion chamber for the primary hot water.

Ret 11394sp

5. A domestic boiler as claimed in any of the preceding claims, wherein the sub-assembly further includes an expansion chamber for the secondary hot water.

6. A domestic boiler as claimed in any of the preceding claims, wherein the 5 sub-assembly further includes a flow-sensing valve for secondary water flow through the heat-exchanger, the motorised valve being controlled to direct substantially all the primary hot water through the heat-exchanger on detecting said flow.

7. A domestic boiler as claimed in any of the preceding claims, wherein the 10 boiler assembly is mounted on a back-plate intended for direct mounting to a wall of a domestic dwelling, and the sub-assembly is mounted directly on the back-plate.

8. A domestic boiler as claimed in claim 7, wherein the back-plate defines an abutment on which the sub-assembly is slidably mounted.

9. A domestic boiler as claimed in claim 8, wherein the sub-assembly is held in position on the abutment by means of interengaging holes and pegs on the boiler assembly and the sub-assembly.

10. A domestic boiler as claimed in claim 8 or claim 9, wherein a screwthreaded fastener is provided to lock the mounting plate to the backplate.

11. A domestic boiler as claimed in any of the preceding claims, wherein the sub-assembly one part of an electrical plug and socket connector to which those components of the sub-assembly requiring electrical services are wired, the other part of the connector being wired to components of the boiler assembly.

Ref 11394sp 1.

12. A domestic boiler for producing primary hot water for space heating and also secondary hot water for domestic use and substantially as hereinbefore, described with reference to and as illustrated in the accompanying drawings.