A boiler system comprises a housing with a generally cylindrical shape extends between first and second walls to provide a generally cylindrical space. A fire tube is positioned near a bottom of the generally cylindrical housing and extends longitudinally from a first wall of the cylindrical housing to a fire tube end wall. The boiler system also includes a burner with a generally cylindrical housing which defines a generally cylindrical chamber and an end plate. The burner extends into the fire tube, and the fire tube provides a combustion chamber where combustion of an air-fuel mixture is accomplished using the burner. The end plate of the burner is adjustable so as to adjust the flame that extends from within the burner housing into the fire tube.

A baffle for a thermal transfer device can include a body having a multiple first apertures that traverse therethrough, where each first aperture has a first outer perimeter that includes a first base shape and at least one first protrusion extending from the first base shape. Each of the first apertures is configured to receive a tube. The first base shape of each first aperture has a first shape and a first size that is configured to be substantially the same as the first shape and the first size of an end of a tube.

A baffle for a fluid collection portion of a thermal transfer device can include a body having an inner perimeter, an outer perimeter, and an asymmetric feature, where the asymmetric feature is configured to create a pressure drop within the fluid collection portion of the thermal transfer device. The inner perimeter can be configured to be at least as large as an inner surface of a first wall that forms the fluid collection portion of the thermal transfer device. The outer perimeter can be configured to be no larger than an outer surface of a second wall that forms the fluid collection portion of the thermal transfer device.

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 baffle for a fluid collection portion of a thermal transfer device can include a body having an inner perimeter, an outer perimeter, and an asymmetric feature, where the asymmetric feature is configured to create a pressure drop within the fluid collection portion of the thermal transfer device. The inner perimeter can be configured to be at least as large as an inner surface of a first wall that forms the fluid collection portion of the thermal transfer device. The outer perimeter can be configured to be no larger than an outer surface of a second wall that forms the fluid collection portion of the thermal transfer device.

A baffle for a thermal transfer device can include a body having a multiple first apertures that traverse therethrough, where each first aperture has a first outer perimeter that includes a first base shape and at least one first protrusion extending from the first base shape. Each of the first apertures is configured to receive a tube. The first base shape of each first aperture has a first shape and a first size that is configured to be substantially the same as the first shape and the first size of an end of a tube.

A baffle for a thermal transfer device can include a body having a multiple first apertures that traverse therethrough, where each first aperture has a first outer perimeter that includes a first base shape and at least one first protrusion extending from the first base shape. Each of the first apertures is configured to receive a tube. The first base shape of each first aperture has a first shape and a first size that is configured to be substantially the same as the first shape and the first size of an end of a tube.

A boiler includes a tank, a gas circuit that includes a main combustion chamber in the tank and branch tubes in the tank that extend off of the main combustion chamber, and a water circuit fluidly isolated from the gas circuit. The water circuit includes a first manifold and water tubes that extend off of the first manifold. Each water tube extends through a respective one of the branch tubes, which may serve to preheat the water prior to discharge of the water into the tank.

A boiler includes a tank, a gas circuit that includes a main combustion chamber in the tank and branch tubes in the tank that extend off of the main combustion chamber, and a water circuit fluidly isolated from the gas circuit. The water circuit includes a first manifold and water tubes that extend off of the first manifold. Each water tube extends through a respective one of the branch tubes, which may serve to preheat the water prior to discharge of the water into the tank.

A baffle for a thermal transfer device can include a body having a multiple first apertures that traverse therethrough, where each first aperture has a first outer perimeter that includes a first base shape and at least one first protrusion extending from the first base shape. Each of the first apertures is configured to receive a tube. The first base shape of each first aperture has a first shape and a first size that is configured to be substantially the same as the first shape and the first size of an end of a tube.