GB2048462A - Fireplace units - Google Patents

Abstract

A fireplace unit (10 Fig. 1) comprises a firebox 14 open on one side, a flue outlet 31 and a water heating manifold 25 positioned inside the firebox and in the path of hot gases travelling to the flue outlet. Heat transfer devices (29 Fig. 3) e.g. heat pipes extend partly within and partly outside the manifold 25. The manifold may be connected into a domestic hot water or central heating system. The firebox may be mounted in a fire housing 11 and spaced therefrom to form an air passageway, so that air may convect through the passageway. <IMAGE>

Description

SPECIFICATION Fireplace unit This invention relates to open fire heating installations and particularly to domestic solid fuel open fires.

Attempts have been made in the past to utilize open fires as the heat sources for central heating or hot water systems. Gener ally, a water jacket is shaped to fit around the back and sides of a firebox. However, since the hot gases of combustion from a fire tend to rise, a large proportion of the heat pro duced by the fire is lost up the chimney. This type of boiler also has the disadvantage that for installation around an existing fire, the fire must be completely removed so that the boiler may be built into the wall and the necessary plumbing carried out.

The invention provides a fireplace unit of the kind comprising a firebox open at a front side and a flue outlet, in which a water heating manifold is positioned inside the fire box in the path of hot gases travelling to the flue outlet, the manifold having inlet and outlet means to allow flow of water into and out of the manifold.

The water heating manifold may comprise heat transfer means located partly within and partly outside the manifold for transferring heat to the water in the manifold.

The heat transfer means may comprise at least one heat pipe as herein defined.

The manifold may be spaced from the fire box to allow the hot gases to pass between the manifold and the firebox.

There may be a housing around the firebox to define a passageway between the firebox and the housing through which air may pass by convection.

A flap may be hingedly mounted adjacent the flue outlet for controlling the flow of combustion gases through the outlet.

The invention further provides a method of installing a water heating manifold in a fire place unit of the type comprising a firebox open at a front side and a flue outlet, which method comprises the steps of forming holes in the firebox to allow passage of inlet and outlet pipes through the firebox, securing the water heating manifold to the manifold on the inside thereof so that, in use, hot gases travel ling to the flue outlet pass over the manifold, and connecting the inlet and outlet pipes to the manifold.

Where the fireplace unit is already posi tioned in a recess in a wall, comprising the further step of removing sufficient masonry from at least one side of the fireplace unit before forming the holes in the firebox.

An embodiment of a fireplace unit and modification thereto according to the inven tion will now be described, by way of exam ple, with reference to the accompanying drawings, in which: Figure 1 is a general perspective view of a domestic fireplace unit, Figure 2 is a sectional view of the fireplace unit of Fig. 1 along the line ll-ll of Fig. 3, and Figure 3 is a sectional front elevation of the fireplace unit of Fig. 1 taken along the line Ill- Ill of Fig. 2, modified by the inclusion of heat pipes in the manifold.

A domestic fireplace unit generally designated 10 comprises a fire housing 11, a firebox 14 open on one side, and a fire basket 1 2 underneath which is positioned an ash pan 1 3. The rear portion of the firebox, generally known as the fireback 20, is inclined towards the open side of the firebox above the fire basket. The fire has a throat defined by the top of the fireback 20 and a plate 21 extending along the width of the firebox 14. The rate of combustion of the fire is regulated by a damper flap 22 which controls according to its position the flow of combustion gases through the throat of the fire. The flap 22 is hingedly mounted on the plate 21, and is operated by a lever 23 secured to the plate 21, the lever 23 being retained between a guide 24 and one side of the firebox.

The firebox 1 4 is spaced from the fire housing 11 at the base and back so as to form a passageway through which air may convect by virtue of being heated through the firebox wall. Towards the top of the air housing 11 the convected air is constricted to a tube 30 which opens out between the plate 21 and the roof of the housing 11. The motion of the convected air is indicated by the arrows in Fig. 2. The combustion gases pass through the throat of the fire, round the exterior of the tube 30 and thence up the flue 31, thus being kept separate from the convected air. The motion of the combustion gases is represented by the arrows in Fig. 3.

A water heating manifold 25 in the form of a closed metal tube of box section is mounted directly above the combustion area of the fire inside the firebox by means of brackets 26 secured to the sides of the firebox 1 4. The manifold 25 is fitted with inlet and outlet pipes 27 and 28 respectively which pass through holes on one side panel of the fire housing 11. A single bracket 26 may be used, on the end of the manifold remote from the pipes, in which the case the other end is supported by the pipes alone. It is also possible to arrange the pipes at the other end of the manifold, or indeed to have the inlet pipe arranged at one end of the manifold and the outlet pipe at the other end of the manifold.A space is maintained between the manifold 25 and the fireback 20 to permit hot gases to pass behind as well as in front of the manifold, thus increasing the rate of heat transfer to the water in the manifold. In the modified embodiment of Fig. 3, the rate of heat transfer is further improved by means of heat pipes 29 which are secured partly inside and partly outside the manifold and extend towards the back of the firebox. Such heat pipes are generally closed tubes containing a liquid and a wick, and in this particular arrangement serve to absorb extra heat from the fire and then transmit it to the water in the manifold.

Heat is transferred by the liquid evaporating at the hotter end of the tube, the vapour travelling to and condensing at the colder end of the tube, condensed fluid returning to the hotter end by capillary action through the wick.

The water heating manifold 25 may be connected into a domestic hot water system and/or a central heating system.

It will be appreciated that although a specific type of fire has been described, a water heating manifold according to the invention may be inserted any sort of open fire.

The manifold 25 may be secured in position in the firebox 1 4 either before insertion of the firebox into a recess in a wall or when the firebox is already inserted.

Where the manifold is to be secured in position before insertion of the firebox, holes are cut in the side of the firebox for the inlet and outlet pipes, the manifold is secured inside the firebox by means of one or more brackets 26 and the inlet and outlet pipes are connected to the manifold. The inlet and outlet pipes can be connected into the appropriate water system on installation of the firebox.

Where the firebox is already in position in a recess in a wall, some masonry will have to be removed to allow access to one side of the firebox, but the firebox can remain in position in the recess. When sufficient masonry has been removed, holes are cut in a side of the firebox for the inlet and outlet pipes, the manifold 25 is secured inside the firebox by one or more brackets 26, and the inlet and outlet pipes are connected to the manifold 25.

The inlet and outlet pipes are connected into the appropriate water systems.

An advantage of the invention is that it provides a simple and therefore cheap facility for heating water, for example for a hot water or central heating system. Another advantage is that a water heating manifold embodying the invention may be easily installed in an existing fire either before or after installation of the fire. Where the fire is already installed, there is no need for the fire to be dismantled or removed from its surround, which is a significant advantage over known back boiler systems, where the fire must be removed completely from its recess in order to allow acess to the rear of the fire.

Claims (10)

1. A fireplace unit of the kind comprising a firebox open at a front side and a flue outlet, in which a water heating manifold is positioned inside the firebox in the path of hot gases travelling to the flue outlet, the manifold having inlet and outlet means to allow flow of water into and out of the manifold.

2. A fireplacs unit as claimed in claim 1 in which the water heating manifold comprises heat transfer means located partly within the manifold and partly outside the manifold for transferring heat to the water in the manifold.

3. A fireplace unit as claimed in claim 2 in which the heat transfer means comprises at least one heat pipe.

4. A fireplace unit as claimed in any preceding claim in which the manifold is spaced from the firebox to allow the hot gases to pass between the manifold and the firebox.

5. A fireplace unit as claimed in any preceding claim further comprising a housing around the firebox to define a passageway between the firebox and the housing through which air may pass by convection.

6. A fireplace unit as claimed in any preceding claim further comprising a flap hingedly mounted adjacent the flue outlet for controlling the flow of combustion gases through the outlet.

7. A method of installing a water heating manifold in a fireplace unit of the type comprising a firebox open at a front side and a flue outlet, which method comprises the steps of forming holes in the firebox to allow passage of inlet and outlet pipes through the firebox, securing the water heating manifold to the manifold on the inside thereof so that, in use, hot gases travelling to the flue outlet pass over the manifold, and connecting the inlet and outlet pipes to the manifold.

8. A method of installing a water heating manifold as claimed in claim 7 where the fireplace unit is already positioned in a recess in a wall, comprising the further step of removing sufficient masonry from at least one side of the fireplace unit before forming the holes in the firebox.

9. A fireplace unit substantially as hereinbefore described with reference to and as shown in Figs. 1 and 2 or as modified in Fig.

3 of the accompanying drawings.

10. A method of installing a water heating manifold substantially as hereinbefore described with reference to the accompanying drawings.