CPC F24H 1/107 (2013.01) [F24H 8/006 (2013.01); F28D 1/0472 (2013.01); F28D 7/0075 (2013.01); F28D 7/024 (2013.01); F28D 9/0012 (2013.01); F28F 1/24 (2013.01); F28D 2021/0024 (2013.01); F28F 2275/04 (2013.01)] | 21 Claims |
3. A water heater comprising:
an outer casing defining a longitudinal axis, an axial direction being defined as extending along the longitudinal axis;
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 including 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;
wherein the primary heat exchanger and the secondary heat exchanger are in fluid communication such that the flue gases flow from the combustor then through the primary heat exchanger and then through the second set of passages before being exhausted, and water to be heated flows through the first set of passages then through the tube and then to a delivery point for use upon demand,
wherein the secondary heat exchanger includes a spiral flow path, and wherein the water is configured to be directed along the spiral flow path, and
wherein the spiral flow path is formed by a coupling member spiraling from a first end to a second end of each plate to form the spiral flow path.
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