A fire tube boiler includes a perforated flame holder configured to hold a combustion reaction that produces very low oxides of nitrogen (NOx).

An existing single-pass sectional boiler is retrofitted with one or two replacement sections to become a multi-pass boiler. One intermediate section of the original boiler is replaced by a new section having a downwardly extending water-filled target wall portion that divides the original combustion chamber into a smaller combustion chamber on the front side and a heat exchange chamber on the rear side of the target wall portion. The target wall portion also forces at least most of the combustion gas to flow from the combustion chamber upwardly through a first flue passage of the boiler's heat exchanger, into the upper flue collector chamber. Another intermediate section of the original boiler may be replaced by a new section having an upwardly extending draft diverter portion, or a draft diverter is installed in the upper flue collector chamber, to divert the flue gas back downwardly through a second flue passage of the heat exchanger to the heat exchange chamber. From there, the flue gas flows again upwardly through a third flue passage of the heat exchanger to the breech.

A heat exchanger arrangement (10), especially for a fuel-operated vehicle heater, includes an outer pot-shaped housing (12) having an outer bottom wall (16) and an outer circumferential wall (18) extending along a longitudinal axis (L). An inner pot shaped housing (14) has an inner bottom wall (20) and an inner circumferential wall (22) extending along the longitudinal axis (L). A flow space (24) for fluid whose temperature is to be regulated is formed between the inner housing (16) and the outer housing (12). At least one liquid uptake volume (46, 48) for taking up liquid condensed in the inner housing (14).

The present invention provides a boiler system, for example for use in heating a domestic hot water supply, and which is significantly more fuel efficient than existing boilers, the boiler system comprising a first reservoir and a second reservoir which together define a combustion enclosure, a storage tank positioned to define an upper wall or roof of the enclosure and being in fluid communication with the first water reservoir, a heat exchange tube located in the storage tank and being in fluid communication with the second water reservoir; and a burner arranged to directly heat atmospheric gases within the enclosure in order to indirectly heat the walls of the enclosure.

The present invention provides a boiler system, for example for use in heating a domestic hot water supply, and which is significantly more fuel efficient than existing boilers, the boiler system comprising a first reservoir and a second reservoir which together define a combustion enclosure, a storage tank positioned to define an upper wall or roof of the enclosure and being in fluid communication with the first water reservoir, a heat exchange tube located in the storage tank and being in fluid communication with the second water reservoir; and a burner arranged to directly heat atmospheric gases within the enclosure in order to indirectly heat the walls of the enclosure.

A heat exchanger assembly for a vehicle heating device includes inner heat exchanger housing (12) and outer heat exchanger housing (14). A fluid flow space (24) is formed between the inner heat exchanger housing and the outer heat exchanger housing. Flow guiding formations (40, 42), along circumferential walls (18, 22) of the housings, divide a portion of the fluid flow space into a first partial flow space (44) and a second partial flow space (46). A fluid inlet opening (49) opens to the first partial flow space and at least one fluid outlet opening (51) opens to the second partial flow space (46). A press fit formation (94) fixes the inner heat exchanger housing in relation to the outer heat exchanger housing and includes the first flow guiding formation and the second flow guiding formation and/or the press fit formation is in an end region (32) of the circumferential walls.

The present invention provides a boiler system, for example for use in heating a domestic hot water supply, and which is significantly more fuel efficient than existing boilers, the boiler system comprising a first reservoir and a second reservoir which together defme a combustion enclosure, a storage tank positioned to defme an upper wall or roof of the enclosure and being in fluid communication with the first water reservoir, a heat exchange tube located in the storage tank and being in fluid communication with the second water reservoir; and a burner arranged to directly heat atmospheric gases within the enclosure in order to indirectly heat the walls of the enclosure.

A heat exchanger having a drainage member (1) mounted on an open end (322) of a heat-transfer tube (32), wherein the drainage member (1) contains a flow guide portion (11) including an insertion portion (11a) configured to be inserted into the heat-transfer tube (32) from the open end (322), and a projecting portion (11b) projecting toward an outside of the heat-transfer tube (32) from the open end (322) and extending downward.

A vehicle heater heat exchanger arrangement (10) includes: a pot-like heat exchanger housing (12) with a first bottom wall (18) in a first axial end area (16) and with a first circumferential wall (20) adjoining the first bottom wall and enclosing a longitudinal axis (L); and a pot-like outer heat exchanger housing (14) with a second bottom wall (22) in the first axial end area and with a second circumferential wall (24) adjoining the second bottom wall and enclosing the longitudinal axis. The inner heat exchanger housing and the outer heat exchanger housing are connected to one another in a second axial end area (26) and a fluid flow space (34) is formed between the inner heat exchanger housing and the outer heat exchanger housing. The second axial end area has an outwardly open recess (60) defined by the inner heat exchanger housing or/and by the outer heat exchanger housing.

A co-fired generator for use in a continuous-cycle absorption heating and cooling system may provide heat to the interior of an annulus chamber from a first heat exchanger, such as a firetube heat exchanger, supplemented by heat to the exterior of the annulus chamber from a second heat exchanger containing fluid heated by an external source. Some embodiments may circulate fluid heated in a solar-heated collector through the second heat exchanger. Other embodiments may route exhaust gas from a combustion engine through the second heat exchanger. The second heat exchanger may be provided with a plurality of fins to increase the surface area available for thermal transfer between the heated fluid and the annulus chamber.