GB2063451A

GB2063451A - Heater

Info

Publication number: GB2063451A
Application number: GB8027467A
Authority: GB
Original assignee: Nefit BV
Current assignee: Nefit BV
Priority date: 1979-08-28
Filing date: 1980-08-22
Publication date: 1981-06-03
Also published as: DE3032120A1; FR2464437B3; FR2464437A1; GB2063451B; NL7906458A

Abstract

A heater, particularly a heater for a central heating system, comprises a combustion chamber (2) in which a burner (5) is arranged having a number of burner openings, a heat exchanger for a fluid to be heated, a combustion air feed (3, 12) and an outlet (4) for the combustion gases, said heater further comprising means (17) for forcing the discharge of the combustion gases. The burner of the heater is formed by a wall of a mixing chamber (7) for the fuel and the total amount of combustion air, said wall being provided with burner openings facing the heat exchanger (6), and being positioned outside the area covered by the vertical projection of the heat exchanger and the bottom of the combustion chamber. <IMAGE>

Description

SPECIFICATION Heater The present invention relates to a heater, comprising a combustion chamber in which a burner is arranged having a number of burner openings, a heat exchanger for a fluid to be heated, a combustion air feed and an outlet for the combustion gases, said heater further comprising means for forcing the discharge of the combustion gases.

Similar, known, heaters are frequently used, for instance, in central heating systems. A disadvantage of heaters of this type is that their construction is rather voluminous.

It is an object of the present invention to provide a heater having a very compact construction and an increased efficiency.

According to the invention, this object is attained in that the burner is formed by a wall of a mixing chamber for the fuel and the total amount of combustion air, which wall is provided with the burner openings and faces the heat exchanger, said wall being positioned outside the area covered by the vertical projection of the heat exchanger on the bottom of the combustion chamber.

As all air required for the relative combustion is supplied through the mixing chamber, said combustion chamber has no inlet openings for secondary air. The latter arrangement also incurs a lower height of the respective flame. The burner openings can thus be arranged very close to one another, so permitting a very efficient use of the total surface of the burner.

Up to the present the combustion gases of heaters could not possibly be cooled below their condensation temperature, as the condensate, which is mixed with soot- and/or corrosionparticles, would drip from the heat exchanger, and then be deposited on the burners thus disturbing the operation. Efforts have been made to meet this disadvantage by arranging a second heat exchanger in the outlet outside the combustion chamber. In this manner, however, the compact construction of the heater is affected, while such a construction is further complicated and, therefore, expensive.

According to the invention, the mixing chamber is preferably positioned above the heat exchanger, the wall facing downwards.

In combination with the position of the burner, a desired flow pattern of the combustion gases is so obtained, whilst the space below the heat exchanger remains available for collecting and discharging the relative condensate.

Preferably the means for the forced discharge of the combustion gases comprises a fan which is arranged in the inlet aperture of the mixing chamber. By regulating the pressure difference between the mixing chamber and the combustion chamber, the proportion gas-air can be easily adjusted so that an optimum combustion can be obtained.

The present invention will be illustrated in detail with reference to the accompanying drawings presenting, by way of example, two embodiments of an apparatus according to the invention.

Fig. 1 is a schematic cross section of a heater according to the invention.

Fig. 2 is a cross section according to line Il-Il in Fig. 1; and Fig. 3 is another embodiment of the heater according to the invention.

In Figures 1 and 2, the water heater comprises a housing 1 defining a combustion chamber 2, an air feed 3 and a discharge channel 4 for the combustion gases. Near the top of the combustion chamber a burner 5 is arranged below which a heat exchanger is accommodated for a fluid to be heated. The burner 5 is formed by a mixing chamber 7 of which the wall facing the heat exchanger is provided with burner openings, this mixing chamber being connected with the airfeed 3 through an aperture 8. Near the aperture 8 the mouth of a fuel supply tube 9 is arranged.

The combustion chamber 2 comprises a refractory wall 10 which, is surrounded at distance by an outer casing 11, a space being left between the wall and the casing which space is part of the airfeed 3. The inlet opening 12 of this airfeed 3 is located concentrically around the outlet channel 4 for the combustion gases.

The bottom 13 of the combustion chamber 2 is provided with a channel 14 for discharging the condensate emanating from the heat exchanger, which channel is somewhat inclined and, at the lowest point, provided with an outlet 1 5.

The part of the heat exchanger where condensate is formed is provided with strips 16, guiding the condensate from the heat exchanger to the channel 14.

Finally a fan 1 7 is arranged in the flue outlet for a forced discharge of the combustion gases.

In the embodiment of the invention shown in the Figs. 1 and 2, the burner formed by the mixing chamber is placed on the upper side of the combustion chamber. In this mixing chamber, the combustion air supplied through the airfeed 3 is mixed with the fuel, after which the combustible mixture flows in a downward direction through the burner apertures into the combustion chamber where the final combustion takes place.

This position of the burner also offers the advantage that the respective flames are very short, as a result of which the heat exchanger can be placed closer to the burner and the combustion chamber, kept as small as possible. This results in a very compact construction of the heater.

By means of the fan 1 7 the combustion gases are subsequently discharged in a direction contrary to their natural draught and within the combustion chamber these gases can be cooled to a temperature lower than their condensation temperature. The condensate formed near the underside of the heat exchanger flows along the strips 1 6 and is collected in the channel 14 from which this condensate can be discharged through the outlet 1 5.

Fig. 3 shows another embodiment of the invention in which similar parts are referenced by similar numerals.

In this embodiment the fan 17 for obtaining a forced draught is not arranged in the discharge channel for the combustion gases, but in the aperture 8 of the mixing chamber 7. Thus the fan does not come into contact with the combustion gases, so that corrosion thereof by harmful components, if any, is avoided. The burner 5 is arranged near the heat exchanger, the wall with the burner apertures being vertical and the combustion gases flowing in a substantially horizontal direction through the combustion chamber. The strips 1 6 for guiding the condensate are in the case arranged on the side of the heat exchanger opposite the burner.

The forced draught allows the burner to be placed in any position desired, all the air necessary for the combustion being supplied via the mixing chamber so that wall 5 of the burner can cover the total cross-section of the combustion chamber, since no secondary air need be supplied.

These features also contribute to a very small combustion chamber and consequently to a very compact construction of the heater and to an optimum utilization of the respective combustion heat. Any loss of heat, via the walls 10 of the combustion chamber is avoided, as the combustion air is guided to the mixing chamber via a casing arranged around said combustion chamber.

As compared with conventional heaters, the features in accordance with the invention thus increase the efficiency of the present heater by about 20%, so that a considerable economy on expenditures is obtained.

Claims

1. Heater comprising a combustion chamber in which a burner is arranged having a number of burner openings, a heat exchanger for a fluid to be heated, a combustion air feed and an outlet for the combustion gases, said heater further comprising means for forcing the discharge of the combustion gases, and the burner is formed by a wall of a mixing chamber for the fuel and the total amount of combustion air, which wall is provided with the burner openings and faces the heat exchanger, said wall being positioned outside the area covered by the vertical projection of the heat exchanger on the bottom of the combustion chamber.

2. Heater according to claim 1, characterised in that, the wall of the mixing chamber substantially extends along the total cross-section of the combustion chamber.

3. Heater according to claim 1 or 2, characterised in that, the mixing chamber is positioned above the heat exchanger, the wall facing downwards.

4. Heater according to any of the preceding claims, characterised in that the means for the forced discharge of the combustion gases comprises a fan, arranged in the inlet aperture of the mixing chamber.

5. Heater substantially as hereinbefore described with reference to Figs. 1 and 2 or Fig. 3 of the accompanying drawings.

6. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.