GB2238378A

GB2238378A - Fresh air supply and exhaust gas discharge arrangement for a fuel-fired heat source

Info

Publication number: GB2238378A
Application number: GB9022841A
Authority: GB
Inventors: Ralf Heidemeyer; Martin Hogelucht
Original assignee: Joh Vaillant GmbH and Co
Current assignee: Vaillant GmbH
Priority date: 1989-10-20
Filing date: 1990-10-19
Publication date: 1991-05-29
Anticipated expiration: 2010-10-19
Also published as: ATA240789A; BE1004865A6; AT392688B; NL9002276A; GB2238378B; DE9014469U1; GB9022841D0

Abstract

A fresh combustion air supply and exhaust gas discharge arrangement for a fuel-fired, fan-assisted heat source (3) installed in a room (2) of a building (1) having a roof (8) has the latter penetrated by a flue gas passageway (14) of the arrangement, and an inlet opening (12) for the fresh air provided between the room (2) and the roof (8). <IMAGE>

Description

Fresh Air Supply and Exhaust Gas Discharge Arranaement for a Fuel-fired. Fan-assisted Heat Source The present invention relates to a fresh air supply and exhaust gas discharge arrangement for a fuel-fired, fan-assisted heat source, preferably a circulating water heater, which is installed in an installation room of a building having a roof which is penetrated by a passageway of the arrangement, in which the arrangement is provided with an inlet opening for fresh air between the installation room and the roof.

Such a fresh air supply and exhaust gas discharge arrangement is described in Austrian Patent Application No. 1365/88. In that arrangement, fresh air is sucked from a region above the roof and is conducted through concentric piping into the housing of the fuel-fired heat source. It is there used for combustion, and is subsequently returned through an inner exhaust gas pipe of the concentric piping to the atmosphere above the roof.

The inflowing cold air results in a strong undercooling of the outside surface of the exhaust gas discharge pipe so that condensate may be formed there. Any condensate which has been formed will flow down by gravity and will wet successive pipe portions and possibly also the fuel-fired heat source itself. This may result in corrosion phenomena with all their known undesirable consequences.

It is an aim of the present invention to reduce the extent to which such an arrangement is subject to such a disadvantage.

Accordingly, the present invention is directed to an arrangement as set out in the opening paragraph of the present specification, in which the arrangement is provided with an inlet opening for fresh air between the installation room and the roof.

Owing to such a design, it is possible to suck the fresh air not directly from the external atmosphere above the roof but from an attic space, which is preheated relative to the external atmosphere. As a result, condensation phenomena will be considerably reduced and may even be avoided entirely under certain circumstances.

Besides, any openings provided in the ridge of the roof for the exhaust gas alone can be retained in the event of a replacement of the heat souce. A further advantage of such an arrangement is that it may be substantially independent of the specific shape of the roof and of the construction of the exhaust gas outlet on the roof. For example, the exhaust gas outlet may be provided on the ridge, that is to say at the highest point of the gable roof or hipped roof, but it may also be positioned at an intermediate level or a low level, and may also be provided on a flat roof.

Preferably, the inlet opening comprises a sheet metal body which is provided with openings and through which an exhaust gas passageway of the arrangement extends. In that case a concentric arrangement for the fresh air supply passageway and exhaust gas discharge passageway may terminate, in a direction away from the heat source, downstream of the inlet opening, so that the inlet opening may be constituted by a member which can easily be inserted into piping of one or both of the passageways.

Advantageously, the sheet metal body provided with the inlet openings comprises a double hollow conical frustum having an outer wall and an inner wall which have different angles of taper, the base of the conical frustum is attached to an exhaust gas pipe of the arrangement which leads to an outlet for exhaust gas, and the two apices of the conical frustums are fitted by means of short pipe lengths into or onto pipe lengths which constitute concentric ducting. Thus, if the member forming the inlet opening is conical, an exhaust gas pipe which is relatively small in cross-section may merge, beyond a length of concentric ducting, into a pipe of relatively large cross-section for the remainder of the exhaust gas discharge passageway, to the exhaust gas outlet opening.This may reduce pressure loss in the path of the exhaust gas, with a reduction in the required power for the fan of the heat source. In other words, longer exhaust gas lines may be provided with a reduced pressure differential, enabling a greater variety in the possible locations for the fuel-fired heat source which may be selected.

Examples of an arrangement constructed in accordance with the present invention are illustrated in the accompanying drawings, in which: Figure 1 is a transverse sectional view of a house provided with such arrangements; and Figure 2 shows on a larger scale a detail of a fresh air supply and exhaust gas discharge line of an arrangement shown in Figure 1.

A house 1 comprises one or more dwelling rooms 2. A circulating water heater 3 is provided in one or more of the dwelling rooms 2, the or each of which is called the installation room. The heater 3 is a central heating appliance, which is mounted on a wall and comprises an atmospheric gas burner. A fan is provided in a fresh air supply line leading to the circulating water heater or in an exhaust gas discharge line of ducting 5 from the circulating water heater. Instead of a circulating water heater, a fuel-fired water reservior or one or more gas furnaces or a heater for water for consumption may be employed.

The concentric fresh air supply line and the exhaust gas discharge line of the ducting 5 are concentric and are attached to and extend upwardly from the top 4 of a fuelfired heat source of the heater 3. Those lines extend through the ceiling 6 of the upper-most storey (or the floor of an attic space 7) and through the attic space 7 below a steep tiled roof 8, which at its top has a ridge 9. The ridge 9 is provided at its top with an exhaust gas outlet 10. Outflowing exhaust gas is illustrated by arrows 11. The concentric fresh air supply line and the exhaust gas discharge line of the ducting 5 are concentric or partly concentric at least in a region between the heat source 3 and an inlet 12 for fresh air, indicated by arrows 13. Such lines are known. The internal space is defined by an exhaust gas pipe, which is spaced from and surrounded by a fresh air pipe. The space of annular cross-section between the two pipes constitutes the fresh air line or passageway and the inner space within the inner pipe constitutes the exhaust gas line or passageway.

Above the inlet 12, only a part of the exhaust gas discharge line 14 is provided, which extends as far as the exhaust gas outlet 10. In one of the illustrated examples the exhaust gas outlet 10 is provided in the ridge 9, at an uppermost point of a gable roof or hipped roof. In an alternative illustrated example shown on the extreme left of Figure 1, the exhaust gas outlet 10 and the associated line part 14 may extend through the roof at an intermediate or low level.

The extreme right-hand part of Figure 1 shows a further alternative example in which the roof 8 is almost planar (except for a slight inclination, not evident from Figure 1) for water drainage. An attic space 7 is also provided. The inlet 12 serves to supply air from the attic space 7 to the fuel-fired heat source. That air can be warmed by dissipated heat which is transferred through the floor 6 above the uppermost storey.

The region of the inlet 12 is shown in greater detail in Figure 2. The inlet comprises a sheet metal part 15, by which a part 16 of the concentric ducting 5, which includes a part of the fresh air supply line and a part of the exhaust gas discharge line, is connected to the part 14 of the exhaust gas discharge line. The sheet metal part 15 constitutes a concentric double conical frustum, in which a tight-fitting inner conical wall or sheet plate 17 extends from the base 18 of the inverted conical frustum to the apex 19 of the conical frustum, where a short length of pipe 20 is attached, which may be fitted into or onto the part 14 of the exhaust gas discharge line. An outer cone plate or sheet plate 23 is welded to the base 18 and has a large number of openings 24, which permit air from the attic space 7 to enter the internal space between the two plates 17 and 23 and from there to the annular space 26, which constitutes the fresh air passageway, from which the air flows further to the fuelfired heat source. The frustoconical outer plate 23 has an apex 27 from which a further short length of pipe 28 extends, which is fitted into the outer pipe 29 of the ducting 5 or onto that pipe 29.

Claims

1. A fresh air supply and exhaust gas discharge arrangement for a fuel-fired, fan-assisted heat source, preferably a circulating water heater, which is installed in an installation room of a building having a roof which is penetrated by a passageway of the arrangement, in which the arrangement is provided with an inlet opening for fresh air between the installation room and the roof.

2. An arrangement according to claim 1, in which the inlet opening comprises a sheet metal body which is provided with openings and through which an exhaust gas passageway of the arrangement extends.

3. An arrangement according to claim 2, in which the sheet metal body provided with the inlet openings comprises a double hollow conical frustum having an outer wall and an inner wall which have different angles of taper, the base of the conical frustum is attached to an exhaust gas pipe of the arrangement which leads to an outlet for exhaust gas, and the two apices of the conical frustums are fitted by means of short pipe lengths into or onto pipe lengths which constitute concentric ducting.

4. An arrangement according to any preceding claim, in which at least a part of the fresh air supply passageway and at least a part of the exhaust gas discharge passageway are arranged concentrically.

5. A fresh air supply and exhaust gas discharge arrangement for a fuel-fired, fan-assisted heat source, substantially as described herein with reference to the accompanying drawings.