GB2466826A

GB2466826A - Condensing boiler and flue assembly

Info

Publication number: GB2466826A
Application number: GB0900299A
Authority: GB
Inventors: William Anthony Byrne; Steve Owen; Ian Thompson; Paul Needley
Original assignee: Valor Ltd
Current assignee: Valor Ltd
Priority date: 2009-01-09
Filing date: 2009-01-09
Publication date: 2010-07-14
Anticipated expiration: 2029-01-09
Also published as: GB2466826B; GB0900299D0

Abstract

A condensing boiler 36 has a combustion chamber, an exhaust flue 46 for exhaust of combustion products, and first and second heat exchangers located between the combustion chamber and the exhaust flue. The first heat exchanger is provided for extracting heat from the combustion products. The second heat exchanger is located downstream of the first heat exchanger for extracting latent heat from the combustion products. The boiler further comprises a sump 44 located downstream of the second heat exchanger for collecting condensed water vapour from the combustion products. A pump 52 is provided for removing the condensed water vapour from the sump, where the pump is sealingly connected to the sump. In a further aspect, a flue assembly for a boiler is provided comprising a connector (64, fig.7) having outer 76 and inner 80 conduits, and an outer elongate flexible tube 28 with an inner elongate flexible tube 26 mounted within it, where one end of each of the flexible tubes is sealingly connected to one end of each of the conduits, and the connector is secured to a boiler.

Description

DESCRI PTION

CONDENSING BOILER

The present invention relates to condensing boilers and in particular, but not exclusively, to condensing boilers for use as a back S boiler.

A back boiler is a boiler which fits into a fireplace and which is concealed by means of a heater (traditionally a gas-fired heater) located in front. The back boiler provides heated water for central heating and/or for a hot water supply while the heating appliance located in front io provides instantaneous, direct heat when required.

Where a gas-fired back boiler unit has been used in conjunction with a gas-fired heating unit, air for combustion has normally been taken from the room in which the appliances are situated, rather than through an external supply. As it becomes necessary for older back boiler units to be is replaced, it is desirable (and, indeed, regulated) that they should be replaced with condensing boilers as they are considerably more efficient and therefore more economical, and produce lower CO2 emissions.

It would be desirable for a replacement condensing boiler to be filled as a back boiler, namely in the space previously occupied by the replaced boiler. However, the space available into which to fit a back boiler is limited and there is normally insufficient space for a condensing boiler to be installed as a back boiler. The trend has therefore been to replace existing back boilers with a condensing boiler in a location other than the space occupied by the existing back boiler (e.g. in a kitchen or airing cupboard) and to continue to conceal the existing back boiler with an electrically-actuated appliance positioned in front.

It is an aim of the present invention to provide a condensing boiler suitable for use as a back boiler.

In accordance with a first aspect of the present invention, a condensing boiler comprises a combustion chamber, an exhaust flue for exhaust of combustion products and, located between the combustion chamber and the exhaust flue, first heat exchanging means for extracting heat from the combustion products, second heat exchanging means located downstream of the first heat exchanging means for extracting latent heat from the combustion products, a sump located downstream of io the second heat exchanger for collecting condensed water vapour from the combustion products and a pump for removing the condensed water vapour from the sunip, the pump being sealingly connected to the sump means.

By sealingly connecting the pump means to the sump means, it is is not necessary to provide a condensate trap or siphon, which permits a compact construction. Moreover, by designing the appliance with a separate air duct, the sealed mounting of the pump with respect to the sump means results in the condensing boiler being completely room sealed, which ensures that combustion products cannot escape into the room in which the boiler is situated.

Preferably, the pump means is sealingly mounted on the sump means.

Preferably, the base wall of the sump means is inclined downwardly towards the location of the pump means, whereby the condensed water vapour collects in the vicinity of the pump means.

It is a preferred feature that the sump means comprises an aperture in which the pump means is sealingly located.

Preferably, the aperture in which the pump means is sealingly located is provided in an extended portion of the surnp means.

Preferably, the extended portion extends laterally.

Preferably, the sump means is provided with means for determining the level of condensate within the sump means, e.g. a float switch, and preferably the pump means is actuated to evacuate condensate when the condensate has reached a predetermined level or depth.

The boiler preferably comprises control means for controlling and/or monitoring its operation.

0 A further problem with the installation of a condensing boiler as a back boiler is the lack of available space. This causes particular problems with the connection of an external exhaust flue to the boiler.

Failure to connect the external exhaust flue correctly can result in combustion products being discharged into the room where the boiler is is located, which can have serious adverse consequences. Similarly! if the air inlet is not connected correctly, inefficient combustion and/or escape of combustion gases into the room where the boiler is located can occur.

It is therefore an aim of the present invention to facilitate connection of inlet and exhaust flues to a boiler in circumstances where space is limited and where it might be difficult to make such connections after the boiler as been installed.

In accordance with a second aspect of the present invention, a flue assembly for a boiler comprises a connector means, an outer elongate flexible tube and an inner elongate flexible tube within the outer elongate flexible tube, the connector means having outer and inner conduits, first and second attachment means for sealing connection of one end of each of the outer and inner elongate flexible tubes to one end of the first and second conduits respectively and means for securing the connector means to a boiler whereby the opposite ends of the first and second conduits are aligned with, and in sealing engagement with, first and second apertures respectively of the boiler.

Such an arrangement allows the innermost ends of the outer and inner elongate flexible tubes to be securely and sealingly connected to the connector means prior to installation of the boiler. The boiler can then be installed, whereupon it is necessary merely for the connector means to be attached to the boiler in a predetermined position, which automatically io brings the outer and inner flexible conduits into sealing communication with apertures (for inlet of air for combustion and for exhaust of combustion products or vice versa) on the boiler.

In particular, it is not necessary for the outer and inner flexible conduits to be connected directly to the relevant apertures of the boiler in is situ, which overcomes the potential disadvantage that it is difficult to be certain that sealing connections directly between the outer and inner flexible conduits and the boiler have been made. With the present invention, the outer and inner flexible conduits are secured to the connector means and since this is done before the boiler is installed, much more space is available for a litter to make the sealing connections between the tubes and the connector. Sealing connection can be ensured and the connection of the flexible flues is not hindered by the presence of the boiler.

In one embodiment, the outer elongate flexible flue is adapted to supply air for combustion and the inner elongate flexible flue is adapted to discharge combustion products from the boiler.

In one embodiment, the means for securing the connector means to a boiler comprises a plurality of projections on one of the connector means and the boiler which are adapted to be received in corresponding recesses on the other of the connector means and the boiler. The projections are preferably threaded and are preferably adapted to be received in apertures. In a preferred embodiment, the projections are located on the boiler and the recesses are located on the connector means.

In one embodiment, the connector means comprises base portion to which the inner and outer conduits are connectable, preferably releasably connectable. The outer conduit may be sealingly received in a collar portion of the connector means.

By way of example only, a specific embodiment of the present invention will now be described, with reference to the accompanying drawings, in which: Fig. I is a perspective view of an embodiment of back boiler unit ("BBU") in accordance with the present invention; Fig. 2 is a perspective view of the BBU of Fig. 1, with the front cover removed; Fig. 3 is a front elevation of the BBU as shown in Fig. 2, with a number of pipes removed, for clarity; Fig. 4 is a plan view of the BBU as shown in Fig. 3, with the top wall removed; Fig. 5 is a perspective view of the BBU as shown in Fig. 2, with the main part of the combustion portion of the BBU removed, to show the sump; Fig. 6 is a plan view of the BBU as shown in Fig. 5; Fig. 7 is a perspective view of the housing of the BBU of Fig. 1, shown with the front panel and burner assembly removed, but illustrating the flue arrangement; Fig. 8 isa plan view of the BBU as shown in Fig. 7; and Fig. 9 is a transverse cross-section of the BBU as shown in fig. 7, looking in the direction of arrows IX -IX.

A back boiler unit (hereinafter "BBU") 10 comprises a metal casing having planar parallel side walls 12, 14, a planar rear wall 16 extending perpendicularly to the side walls 12, 14 and planar top and base walls 18, 19, extending perpendicularly to the side walls and a planar front wall 20 which is hingedly attached to the side wall 14 along one of its vertical edges. The front face of the front wall 20 is provided with controls and displays 22 which are connected to an electronic control unit (not illustrated) on the inner face of the front wall 20, immediately behind the is controls and displays 22. As best seen in Figs. 7 to 9 a flue mounting assembly 24 is also secured to the upper wall 16, from which flexible inner and outer concentric flues 26, 28 extend, as will be explained.

An outlet pipe 30 for heated water passes through side wall 12 adjacent to its frontmost vertical edge, towards the top end of the side wall and similarly a water flow return pipe 32 passes through the side wall 12 at a position adjacent to the frontmost vertical edge and adjacent to its lowermost horizontal edge. A gas inlet pipe 34 also passes through the side wall 12 adjacent to the lowermost edge of the side wall, behind the return pipe 32.

As best seen in Figs. 2 to 4, the housing encloses a condensing boiler shown generally at 36. The condensing boiler has an inlet fan 40 which draws air from the flue 28 into the unit. The air is mixed with combustible gas fed via inlet pipe 34 and is burned in the conventional manner to produce hot exhaust gases which are used to heat water returning to the boiler via the return pipe 32. As for conventional condenser boilers, the exhaust gases pass over a secondary heat S exchanger (not visible) within the heat engine of the boiler 36 to extract further heat. After passing over the further heat exchanger, the exhaust gases pass downwardly to a sump 44 which is sealingly connected to the base of the boiler unit 36. The cooled exhaust gases then pass upwardly to a flattened internal exhaust flue 46 located on the right-hand side of the burner unit when looking from the front, the internal exhaust flue terminating in a flattened, generally horizontal upper portion 48 located above the boiler 36. As shown in Fig. 4, the top portion of the internal exhaust flue 46 is provided with an exhaust aperture 50. The exhaust aperture 50 is adapted to connect sealingly to the inner pipe 26 of the flue arrangement1 as will be explained, whereby the exhaust gases can be exhausted to atmosphere.

One of the features of a condensing boiler is that, as a result of the lower temperature of the final exhaust products as compared with a non-condensing boiler, water vapour produced from combustion condenses within the boiler unit. In the present case, condensed water vapour collects in the sump 44 to which the heat engine and internal exhaust flue 46 are sealingly connected. The sump 44 thereby forms an integral part of the combustion unit.

As illustrated in the Figures, a pump 52 for pumping out condensed water vapour collected in the surnp 44 is provided. The pump is located in an aperture 54 in an upper wall 56 of a side extension 58 of the sump and it will be noted that the base wall 60 of the sump slopes towards the pump 52, whereby condensed water collects in the vicinity of the pump. A float switch 62 is also provided in the sump 44, whereby the pump 52 for removal of condensed water is only operated when the water within the sump 44 reaches a predetermined level. The water from the sump 44 is exhausted to drain via a flexible sump exhaust pipe 58.

The flue arrangement is shown in more detail in Fig. 6. The flue arrangement comprises a flexible inner pipe 26 located concentrically within a flexible outer pipe 28. The walls of both the inner pipe 26 and outer pipe 28 are made from plastic and have a concertina-type shape in cross-section, in order to provide the necessary flexibility. The pipes are sealingly connected to a connector in the form of a spigot assembly 64 which itself is releasably connectible to the top wall 18 of the housing.

The spigot assembly 64 comprises a base portion 66 which is generally planar and is formed into a peripherally extending securing is flange 68 having four apertures 70 which are positioned to receive four bolts 72 secured to, and projecting from, the upper face of the top wall 18 of the boiler casing. A tubular collar 74 projects upwardly from the base portion 66 and receives the complementarily-shaped lower end of an outer socket member 76 which can be releasably securable to the collar by means of a retaining bolt 78 which passes screw-threadedly through the collar 74 into contact with the lower end of the outer socket member 76 positioned within the collar 74. The opposite end of the outer socket member 76 is also tubular but of a wider diameter so that it is adapted to receive the one end of the outer flexible pipe 28 as an interference fit.

The spigot assembly 64 also carries an inner socket member 80 which is held apart from the outer socket member 76 by radially-extending retaining fingers 81 (Fig. 8) and which is releasably securable to the collar 74 by means of a second retaining bolt 82 which passes screw-threadedly through the collar 74 into contact with the lower end of the inner socket member 80 positioned within the collar 74. The opposite end of the inner socket member 80 is also tubular but of a slightly larger diameter so that it is adapted to receive the one end of the inner flexible pipe 26 as an interference lit.

The inner socket member 80 forms a first conduit, for passage of exhaust gases from the boiler 36 to the inner pipe 26, and the space between the inner and outer socket members 76, 80 forms a second o conduit, for passage of air from the outer pipe 28 to the boiler 36.

The lower end of the inner socket member 80 is adapted to be a sealing fit with the exhaust aperture 50 of the upper portion 48 of the boiler exhaust flue 46. Similarly, the lower end of the outer socket member 76 is adapted to be a sealing fit with the inlet aperture (not shown) of the boiler 36. Thus, in use the inner and outer flexible pipes 26, 28 are connected to the upper ends of the inner and outer socket members 80, 76 respectively before the boiler is positioned and before the spigot assembly is connected to the boiler 36. The absence of the boiler provides much more space in which to work and allows the formation of reliable seals between the inner and outer socket members 80, 76 and the respective flexible pipes 26, 28, which can even be tested for soundness, if desired.

The boiler 36 is then installed and after it has been correctly sited, the spigot is offered to the top wall 18 of the housing such that the four bolts 72 projecting from the upper wall 18 are received in the four apertures 70 in the securing flange 68, which automatically aligns the outer and inner socket members 76, 80 with the inlet of the boiler and the outlet aperture 50 of the upper portion 48 of the boiler exhaust flue 46.

The spigot assembly 64 is then secured to the upper wall 18 of the boiler by threading retaining nuts onto the projecting bolts 72, thereby correctly and securely locating the spigot assembly -and therefore the inlet and exhaust flues 28,26 -with respect to the boiler 36. The opposite ends of the inner and outer flexible pipes 26, 28 can be secured in position at an exterior location of the building in which the boiler is sited, either before or after the spigot assembly is secured to the boiler.

The invention is not restricted to the details of the foregoing io embodiment.

Claims

CLAIMS1. A condensing boiler comprising a combustion chamber, an exhaust flue for exhaust of combustion products and, located between the combustion chamber and the exhaust flue, first heat exchanging means for extracting heat from the combustion products, second heat exchanging means located downstream of the first heat exchanging means for extracting latent heat from the combustion products, sump means located downstream of the second heat exchanger means for collecting condensed water vapour from the combustion products and pump means for removing the condensed water vapour from the sump, the pump means being sealingly connected to the sump means.
2. A condensing boiler as claimed in claim 1, wherein the pump means is sealingly mounted on the sump means.
3. A condensing boiler as claimed in claim I or claim 2, wherein the base wall of the sump means is inclined downwardly towards the location of the pump means, whereby the condensed water vapour collects in the vicinity of the pump means.
4. A condensing boiler as claimed in any of claims I to 3, wherein the sump means comprises an aperture in which the pump means is sealingly located.
5. A condensing boiler as claimed in claim 4, wherein the aperture in which the pump means is sealingly located is provided in an extended portion of the sump means.
6. A condensing boiler as claimed in claim 5, wherein the extended portion extends laterally.
7. A condensing boiler as claimed in any of the preceding claims, wherein the sump means is provided with means for determining the level of condensate within the sump means.
8. A condensing boiler as claimed in claim 7, wherein the means for determining the level of condensate within the sump means comprises a float switch
9. A condensing boiler as claimed in claim 7 or claim 8, wherein the pump means is actuated to evacuate condensate when the condensate has reached a predetermined level or depth.
10. A condensing boiler as claimed in any of the preceding claims, further comprising control means for controlling and/or monitoring its operation.
11. A flue assembly for a boiler comprising a connector means, an outer elongate flexible tube and an inner elongate flexible tube within the is outer elongate flexible tube, the connector means having outer and inner conduits, first and second attachment means for sealing connection of one end of each of the outer and inner elongate flexible tubes to one end of the first and second conduits respectively and means for securing the connector means to a boiler whereby the opposite ends of the first and second conduits are aligned with, and in sealing engagement with, first and second apertures respectively of the boiler.
12. A flue assembly as claimed in claim 11, wherein the outer elongate flexible flue is adapted to supply air for combustion and the inner elongate flexible flue is adapted to discharge combustion products from the boiler.
13. A flue assembly as claimed in claim 11 or claim 12, wherein the means for securing the connector means to a boiler comprises a plurality of projections on one of the connector means and the boiler which are adapted to be received in corresponding recesses on the other of the connector means and the boiler.
14. A flue assembly as claimed in claim 13, wherein the projections are threaded and are adapted to be received in apertures.
15. A flue assembly as claimed in claim 13 or claim 14, wherein the projections are located on the boiler and the recesses are located on the connector means.
16. A flue assembly as claimed in any of claims 11 to 15, wherein the connector means comprises base portion to which the inner and outer io conduits are connectable.
17. A flue assembly as claimed in claim 16, wherein the inner and outer conduits are releasably connectable.
18. A flue assembly as claimed in any of claims 11 to 17, wherein the outer conduit is sealingly received in a collar portion of the connector means.
19. A condensing boiler substantially as herein described with reference to, and as illustrated in, the accompanying drawings.
20. A flue assembly substantially as herein described with reference to, and as illustrated in, the accompanying drawings.