Abstract: A water heater includes an outer casing defining a longitudinal axis, an axial direction being defined as extending along the longitudinal axis. The water heater further includes a combustor for production of hot flue gases, a primary heat exchanger including a tube positioned within the outer casing, and a secondary heat exchanger including a plurality of plates coupled together by brazing to form a brazed plate heat exchanger. The secondary heat exchanger includes a first set of passages defined between the plates, and a second set of passages defined between the plates and alternating with the first set of passages in the axial direction. The primary and secondary heat exchangers are in fluid communication such that the flue gases flow through the second set of passages before being exhausted, and water to be heated flows through the first set of passages to a delivery point for use upon demand.

Abstract: The invention provides a water-tube boiler and a burner capable of realizing a reduction in NO.sub.x and CO in both the combustion of liquid fuel and the combustion of gaseous fuel. The water-tube boiler comprises a burner which uses liquid fuel or gaseous fuel switchably, characterized in that a plurality of water tubes are arranged into an annular shape in a zone where burning-reaction ongoing gas derived from the burner is present within a combustion chamber. The water-tube boiler comprises a burner which uses either liquid fuel or gaseous fuel. A first water tube array is formed by arranging a plurality of water tubes into an annular shape in a zone where burning-reaction ongoing gas derived from the burner is present within a combustion chamber. Gaps are provided between adjacent water tubes of the first ongoing gas to flow therethrough. A zone is provided around the first water tube array to allow burning reaction to be continuously effected.

Abstract: A package heat exchange system using an expanded surface gas-fired burner to supply heat via a heat exchange coil in a dome above the extended surface heat exchanger which heats domestic hot water and supplies heat via the dome to a radiator for heating a living area of a home. A control system provides for utilizing steam from the extended surface heat exchanger to heat the coil in the dome and maintains a first pressure for supplying the domestic hot water and a higher pressure when radiator heat is called for. The heat for domestic hot water may be further heat transferred in a fourth heat exchanger which adjusts the temperature of the domestic hot water. The heat supplied to the radiator may be self-pumping by utilizing steam and the heat to the radiator may be cut off by supplying a control to the return pipe of the radiator which allows the radiator to fill with condensate from the steam.

Abstract: A package heat exchange system using an expanded surface gas-fired burner to supply heat via a heat exchange coil in a dome above the extended surface heat exchanger which heats domestic hot water and supplies heat via the dome to a radiator for heating a living area of a home. A control system provides for utilizing steam from the extended surface heat exchanger to heat the coil in the dome and maintains a first pressure for supplying the domestic hot water and a higher pressure when radiator heat is called for. The heat for domestic hot water may be further heat transferred in a fourth heat exchanger which adjusts the temperature of the domestic hot water. The heat supplied to the radiator may be self-pumping by utilizing steam and the heat to the radiator may be cut off by supplying a control to the return pipe of the radiator which allows the radiator to fill with condensate from the steam.