A heat exchanger arrangement, especially for a vehicle heater, includes a pot-like heat exchanger housing (12) with an inner wall (22, 24) and with an outer wall (18, 20). A heat carrier medium flow space is formed between the inner wall (22, 24) and the outer wall (18, 20). A first flow opening (54) is provided on the outer wall (18, 20) and, adjoining this, a pump housing (58) made integrally with the outer wall (18, 20) for a heat carrier medium pump is provided.

A liquid heating apparatus includes a top portion with a burner unit, a coil, an external housing, and an internal housing. The burner unit is arranged to burn a fuel so as to generate a downward directed flame. The coil includes first and second layers of windings. The internal housing is arranged within the external housing. The apparatus is in a substantially upright position during operation. A compartment between the internal housing and the external serves as a first liquid reservoir. The flame from the burner unit is peripherally contained by an inner part of the first layer of windings of the coil. The first layer of windings is configured to direct the flame or exhaust gases downwards. The flame or exhaust gases are redirected such that the they contact all of the second layer of windings, the internal housing inner wall, and the first layer of windings

A fluid heating system including: a pressure vessel; an assembly comprising: a heat exchanger core including a second inlet and a second outlet; a first conduit having a first end connected to the second inlet of the heat exchanger core and a second end disposed outside of the pressure vessel; a second conduit having a first end connected to the second outlet of the heat exchanger core and a second end disposed outside of the pressure vessel; and a blower in fluid connection with the first end of the first conduit, wherein the fluid heating system satisfies the condition that a Bulk Heat Flux between the first end of the first conduit and the first end of the second conduit is between 45 kW/m.sup.2 and 300 kW/m.sup.2, and wherein the Pressure Drop between the first conduit and the second conduit is between 3 kiloPascals and 30 kiloPascals.

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.

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).

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.

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 fluid heating system including: a pressure vessel; an assembly comprising: a heat exchanger core including a second inlet and a second outlet; a first conduit having a first end connected to the second inlet of the heat exchanger core and a second end disposed outside of the pressure vessel; a second conduit having a first end connected to the second outlet of the heat exchanger core and a second end disposed outside of the pressure vessel; and a blower in fluid connection with the first end of the first conduit, wherein the fluid heating system satisfies the condition that a Bulk Heat Flux between the first end of the first conduit and the first end of the second conduit is between 45 kW/m.sup.2 and 300 kW/m.sup.2, and wherein the Pressure Drop between the first conduit and the second conduit is between 3 kiloPascals and 30 kiloPascals.