GB2141531A

GB2141531A - Domestic heat exchanger

Info

Publication number: GB2141531A
Application number: GB08413329A
Authority: GB
Inventors: Thomas Bernard Cogley
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-06-16
Filing date: 1984-05-24
Publication date: 1984-12-19
Also published as: GB8413329D0; GB2141531B

Abstract

A heat exchanger for a gas fire comprising a casing 15 having an inlet 20 and an outlet 21 for the passage of flue gases through the casing, the inlet being adapted to be connected to the flue gas outlet 22 of a gas fire 13, and water pipes 10, 18 passing through the casing whereby heat from the flue gases may be transferred to the water. The heat transfer may be increased by fitting metal fins 19 to the water pipes. In addition a water pipe 11 may be disposed within the gas fire above the radiant elements 12. The water piping may be part of a domestic hot water system. <IMAGE>

Description

SPECIFICATION Domestic heat exchanger This invention relates to a heat exchanger especially a heat exchanger for domestic use.

A large proportion of the heat produced by a domestic gas fire is contained in the flue gases and is consequently lost in the discharge of these gases to the atmosphere.

An object of the invention is to utilize the heat contained in these gases.

According to the present invention, there is provided a heat exchanger for a gas fire, the heat exchanger comprising passage means for hot flue gases from the gas fire and passage means for water in contact with the passage means for flue gases whereby, when pipe gases and water are passed through the heat exchanger, heat is transferred from the flue gases to the water. The water may be the water for a hot water supply or for hot water radiators.

In one form of the invention, the heat exchanger comprises a casing having an inlet and an outlet for the passage of flue gases through the casing, the inlet being adapted to be connected to the flue gas outlet of the gas fire, and water pipes (or other means for containing water) passing through the casing whereby heat from the flue gases may be transferred to the water. Fins may be fitted to the water pipes in the casing to increase the heat transfer. Metal fins are preferred for this purpose. The water pipes passing through the casing may extend between two headers, one of which is provided with a water inlet and the other of which is provided with a water outlet.

In another form of the invention, the heat exchanger comprises a water pipe or other water container disposed within the gas fire in the path of the hot flue gases and preferably disposed above the radiant elements of the gas fire.

Preferably these two forms of the invention are combined. The water piping of either form may be part of a domestic hot water system, a cold water feed pipe from the hot water cylinder being connected to one end of the heat exchanger piping and the other end of the heat exchanger piping being connected to the hot water cylinder by a hot water feed pipe. Where the two forms of heat exchanger are combined, their water piping may be connected in series.

The invention will now be further described by way of example with reference to the accompanying schematic drawings, in which: Figure 1 is a rear perspective view of a gas fire fitted with a heat exchanger in accordance with the invention, Figure 2 is a perspective view of the piping system of the heat exchanger shown in Fig. 1, Figure 3 is a section taken on the line 3-3 of Fig: 1, Figure 4 is a cut-away perspective view illustrating a modification of the heat exchanger shown in Figs. 1 to 3, the casing of the heat exchanger being omitted, and Figure 5 is a transverse section of the heat exchanger shown in Fig. 4, but including the casing of the heat exchanger.

In Figs. 1 to 3 of the drawings, a cold water feed pipe 10 supplies water to first heat exchanger in the form of a water container 11 (Figs. 2 and 3) disposed above radiant elements 12 (Fig. 3) of a gas fire 13. A pipe 14 (Fig. 2) connects the outlet of the water container 11 with a second heat exchanger in the form of a casing 1 5 (Figs. 1 and 3) through which the pipe 14 passes. In the casing the pipe 14 branches to include pipes 1 6 and 1 7 (Figs. 2 and 3) which, after passing through the casing, reunite with pipe 14 to form a hot water feed pipe 1 8. The feed pipes 10 and 18 may be connected to the hot water cylinder of a hot water system or to hot water radiators in a central heating system.The branch pipe 1 6 carries metal fins 1 9 for increasing the heat transfer from the pipes 14 15 and 16.

The casing 15, which may be open underneath, is provided with an inlet 20 and an outlet 21. The inlet 20 is attached to the flue gas outlet 22 (Fig. 3) of the gas fire 1 3 at a point where the outlet 22 passes through the backplate 23 of a fireplace in which the gas fire is fitted. The outlet 21 is formed by the open back of the casing which is partly closed by a removable cover plate 24 which hooks onto lugs on the casing. The interior 25 of the gas fire (Fig. 3) provides a passage for flue gases between the radiant elements 1 2 and the outlet 22.

As shown in Fig. 3, the gas fire may also be provided with a conventional convection heater chamber 26 with hot air outlet grille 27.

The pipe 10 may be provided with a safety valve 28 adjacent to the container 11 (Fig. 2).

Pipes 10 and 18 may also be provided with control valves positioned near the points 29 and 30 respectively near where the pipes enter and leave the gas fire.

When the gas fire is in use, cold water supplied to the container 11 from pipe 10 is heated by hot flue gases from the radiant elements 1 2 and the heated water passes on to the pipes 1 4, 1 6 and 1 7 within the casing 1 5. The hot flue gases pass through the interior of the gas fire and through the casing to the atmosphere via the chimney in the base of which the casing is located. In passing through the casing, the hot flue gases further heat the water in the pipes 14, 1 6 and 1 7 and the hot water is returned to the hot water cylinder or radiators by pipe 1 8.

In the modification shown in Fig. 4, water pipes 40, carrying metal fins 41, extend be tween headers 42, 43. Header 42 is provided with a water inlet 44 for connecting to the water pipe 1 4 (Figs. 1 to 3). Header 43 is provided with a water outlet 45 for connecting to the hot water feed pipe 1 8 (Figs. 1 to 3). As may be seen frorn Fig. 5, the water pipes 40 and fins 41 are enclosed within a casing 50, which corresponds to casing 1 5 in Figs. 1 and 3. The casing 50, which is open underneath, is provided with a flue gas inlet 51 (corresponding to the inlet 20, Figs. 1 and 3) and a flue gas outlet 52 (corresponding to the outlet 21, Figs. 1 and 3, but situated at the top of the casing). The heat exchanger shown in Figs. 4 and 5 functions in the same way as that of Figs. 1 to 3, the parts 40 to 45 being substituted for the parts 16, 1 7 and 19.

The invention thus makes use of waste heat from a gas fire to provide at least part of the heat needed for heating water to be used as piped hot water or in radiators and hence provides a considerable saving in heating costs.

Claims

1. A heat exchanger for a gas fire, the heat exchanger comprising passage means for hot flue gases from the gas fire and passage means for water in contact with the passage means for flue gases whereby, when flue gases and water are passed through the heat exchanger, heat is transferred from the flue gases to the water.

2. A heat exchanger as claimed in claim 1, comprising a casing having a inlet and an outlet for the passage of flue gases through the casing, the inlet being adapted to be connected to the flue gas outlet of the gas fire, and water pipes (or other means for containing water) passing through the casing whereby heat from the flue gases may be transferred to the water.

3. A heat exchanger as claimed in claim 2, in which fins have been fitted to the water pipes in the casing to increase the heat transfer.

4. A heat exchanger as claimed in claim 3, in which the fins are of metal.

5. A heat exchanger as claimed in claim 1, which comprises a water pipe or other water container disposed within the gas fire in the path of the hot flue gases.

6. A heat exchanger as claimed in claim 5, in which the water pipe or other water container is disposed above the radiant elements of the gas fire.

7. A heat exchanger as claimed in any one of claims 2 to 4, in which the flue gas inlet of the casing is connected to the flue gas outlet of a gas fire within which also a water pipe or other water container is disposed in the path of the hot flue gases.

8. A heat exchanger as claimed in claim 7, in which the water pipe or other water container within the gas fire is disposed above the radiant elements of the gas fire.

9. A heat exchanger as claimed in any one of claims 2 to 5, wherein the water piping is part of a domestic hot water system, a cold water feed pipe from the hot water cylinder of the system being connected to one end of the heat exchanger piping and the other end of the heat exchanger piping being connected to the hot water cylinder by a hot water feed pipe.

10. A heat exchanger as claimed in claim 7 or 8, in which the water pipe disposed within the gas fire in the path of the hot flue gases is connected to the water pipes passing through the casing (the flue gas inlet of which is connected to the flue gas outlet of the gas fire), a cold water feed pipe from the hot water cylinder of a domestic hot water system being connected to the water pipe disposed within the gas fire and the water pipes passing through the casing being connected to the hot water cylinder by a hot water feed pipe, the arrangement being such that the cold water feed pipe, the water pipe disposed within the gas fire, the water pipes passing through the casing and the hot water feed pipe are connected in series.

11. A heat exchanger as claimed in any one of claims 2 to 4, 7 or 10, in which the water pipes passing through the casing extend between two headers, one of which is provided with a water inlet and the other of which is provided with a water outlet.

1 2. A heat exchanger for a gas fire substantially as hereinbefore described with reference to and as illustrating in Figs. 1 to 3 of the accompanying drawings.

1 3. A heat exchanger as claimed in claim 12, modified substantially as hereinbefore described with reference to and as illustrated in Figs. 4 and 5 of the accompanying drawings.

14. A gas fire in combination with a heat exchanger as claimed in any one of the preceding claims.