GB2187829A

GB2187829A - Gas-fired heating appliance

Info

Publication number: GB2187829A
Application number: GB08705838A
Authority: GB
Inventors: Bernard Walsh
Original assignee: Myson Heating Ltd
Current assignee: Myson Heating Ltd
Priority date: 1986-03-15
Filing date: 1987-03-12
Publication date: 1987-09-16
Also published as: GB2187829B; GB8606458D0; GB8705838D0

Abstract

A gas-fired water heater includes a combustion chamber (10) containing a condensing heat exchanger (11) and a main heat exchanger (12). Hot combustion gases from a burner (14) pass successively over the main and condensing heat exchangers (12) and (11). Water vapour in the combustion gases condenses on the surface of the condensing heat exchanger (11), and the condensed water is passed from a trough (16) along a pipe (17) to a collecting device (20). A discharge duct 24 and sleeve 26 form a siphon which discharges water in bulk from the collecting device (20) thereby reducing the risk of drain blockage. <IMAGE>

Description

SPECIFICATION Gas-fired heating appliance This invention relates to a gas-fired heating appliance including a component on which a condensate can form, and it relates particularly, though not exclusively, to a gas-fired water heater, for example an instantaneous water heater for domestic use or a central heating boiler.

Water heaters which are intended to operate with relatively high efficiency (in excess of 78%) normally include a secondary (also called condensing) heat exchanger on which a condensate, in the form of droplets of water, can form.

The condensate which is rather acidic (typically a Ph of 3) is collected in a trough and conveyed, via a pipe, to a suitable drain, normally outside the building. Particularly in winter time droplets of water have a tendency to freeze in the pipe, causing a blockage and flooding of the heater casing.

It is an object of the present invention to provide a gas-fired heating appliance which at least alleviates this problem.

Accordingly there is provided a gas-fired heating appliance including a component on which a condensate can form and means to collect condensate formed on said component, the collecting means being arranged to discharge a quantity of condensate in bulk. The appliance may be a gas-fired water heater, said component being a condensing heat exchanger.

It will be understood that a water heater in accordance with this invention embraces both instantaneous water heaters for domestic use and central heating boilers.

A water heater in accordance with the present invention, wherein condensate is discharged in bulk, presents a significantly reduced risk of blockage in a discharge pipe.

In one embodiment the collecting means is arranged to operate in accordance with a siphon action, and may comprise a storage vessel for receiving condensate, a discharge duct extending into the storage vessel from a base wall thereof and an enclosure formed around the discharge duct such that, in use, condensate is admitted to the enclosure via an inlet adjacent said base wall as condensate is being discharged from the enclosure via the discharge duct.

In order that the invention may be carried readily into effect an embodiment thereof is now described, by way of example only, by reference to the accompanying drawings of which: Figure 1 shows, in schematic form, a front view of an instantaneous water heater, Figure 2 shows a cross-sectional view through a collecting device used in the water heater shown in Fig. 1, and Figure 3 is a sectional view of part of Fig.

2.

Referring to Fig. 1 of the drawings, an instantaneous water heater comprises a combustion chamber 10 containing a condensing heat exchanger 11 and a main heat exchanger 12 coupled together in series.

Jn this example, the main heat exchanger includes five passes of copper pipe mounted horizontally, in side-by-side relationship, across an upper part of the combustion chamber. For clarity of illustration only one of the passes is shown in the drawing. The condensing heat exchanger includes six passes of pipe which are mounted at the rear of the combustion chamber substantially in a common plane inclined forwardly at a steep angie to the horizontal. Again, only one of the passes is shown in the drawing. As is well known in the art, all pipes are fitted with cooling fins, shown schematically at F, which assist in the exchange of heat. Cool water received at an inlet I to the water heater is routed directly to the condensing heat exchanger and then to the main heat exchanger.An outlet 0 from the water heater is coupled to the outlet side of the main heat exchanger by means of a coil 13 of pipe which is attached to an exterior surface of the combustion chamber, in good thermal contact therewith. The coil affords an additional exchange of heat and also assists in maintaining the combustion chamber at an acceptably low temperature.

Hot combustion gases produced by a burner 14 rise within the combustion chamber and pass successively over the main heat exchanger 12 and the condensing heat exchanger 11. The gases then pass to atmosphere via an outlet duct 1 5 which may be coupled to a suitable flue.

In operation of the water heater, water vapour in the combustion gases condenses on the relatively cold surfaces of the condensing heat exchanger releasing latent heat of condensation. Water droplets form on the pipes and cooling fins of the heat exchanger and these drip into a trough 16 mounted directly below.

In accordance with this example of the present invention, and in contrast to hitherto known arrangements wherein the water droplets are discharged continuously to a drain, the condensate is passed, by means of a pipe 17, to a collecting device 20 arranged to discharge the condensate in bulk.

As will be seen more clearly in the crosssectional view of Fig. 2, the collecting device 20 is constructed so as to discharge the condensate in accordance with a siphoning action.

The collecting device comprises a generally cylindrical storage vessel 21 provided with a closely fitting lid 22. Condensate is received through an inlet opening 33 in the lid and is discharged via a discharge duct 24 formed integrally with a base 25 of the storage ves sel. The discharge duct extends within the storage vessel, the mouth of the duct being at a preset height above the base 25. The lid is formed with a sleeve 26 which partially surrounds the duct 24 to define an enclosure 27.

When the level in the storage vessel reaches the mouth of the discharge duct condensate spills over and is discharged. This initiates a siphoning action with condensate flowing from the storage vessel into the enclosure via a gap 28 between the sleeve 26 and base 25.

In this manner a quantity of condensate which collects in the storage vessel is discharged in bulk, and this arrangement significantly reduces the risk of a blockage occurring in a drainage system coupled to the discharge duct.

It will be understood that although the invention has been described by reference to a gas-fired water heater, the invention also embraces other forms of gas-fired heating appliance, for example a space heater including a condensing heat exchanger arranged to heat cold air.

Referring to Fig. 3, the pipe 17 passes through a recessed portion of the lid 22 into the storage vessel 21. An O-ring 30 is retained in the lid recess 32 by a metal clip 34 to provide a liquid-tight seal between the pipe 17 and the lid 22.

In the embodiment illustrated in Fig. 1, the collecting device 20 is located immediately beneath the combustion chamber 10. The collecting device 20 may however be located at any convenient position relative to the combustion chamber 10.

Claims

1. A gas fired heating appliance comprising a component on which a condensate can form and means to collect condensate characterised in that the collecting means is arranged to discharge a quantity of condensate in bulk.

2. An appliance as claimed in claim 1 which is a gas-fired water heater.

3. An appliance as claimed in claim 1 or claim 2, wherein the component is a condensing heat exchanger.

4. An appliance as claimed in any preceding claim wherein the collecting means includes a siphon device.

5. An appliance as claimed in claim 4, wherein the collecting means includes a discharge duct extending upwardly from the base of the collecting means to define the head of condensate in the collecting means.

6. An appliance as claimed in claim 5 wherein the collecting means includes a cover, and a sleeve extending downwardly from the cover to surround said discharge duct and be spaced from the base of the collecting means.

7. An appliance as claimed in claim 6 including a pipe to pass the condensate from said component to said collecting means.

8. An appliance as claimed in claim 7 in which said pipe is retained in position by an O-ring seal.

9. An appliance substantially as herein described and shown in the accompanying drawings.