Abstract: A forced convection fin tube condensing heat exchanger for supplying heat includes a shell, burner and fin tubes bundle. The burner is at the top of the shell, circular fin tubes bundle installed around the burner tightly, circularly and coaxially. The flue channel which is formed by the shell and a row of fin tubes bundle is below the burner. The flue flows along the flue channel to flue outlet. There are front and rear water manifolds at the two ends of the fin tubes. Water baffles inside the rear water manifold divide the rear water manifold into water inlet and outlet areas. The water enters the small portion of circular fin tubes bundle from water inlet area, through the front water manifold, back to the water outlet area via the main portion of the circular fin tubes bundle. The use of bent fin tube to improves efficiency.

Abstract: A heat exchanger for supplying heat includes a housing, a bundle of helical fin-coil tubes, and a flue channel. The housing includes a burner, a water inlet, a water outlet and a flue gas outlet. The burner is disposed on a top portion of the housing and connected to an air/gas mixture unit. The bundle of helical fin-tube coils is disposed tightly, circularly, and coaxially around the burner. The flue channel is disposed below the burner and is formed by a plurality of serpentine bent fin-tube coils. A flow of flue gas vents from the flue channel to the flue gas outlet. The water inlet is connected to the plurality of serpentine bent fin-tube coils which forms the flue channel below the burner. The plurality of serpentine bent fin-tube coils below the burner are connected to the bundle of helical fin-tube coils. The bundle of helical fin-tube coils are connected to the water outlet.

Abstract: A heat exchanger for supplying heat includes a housing, a bundle of dual-ring, straight fin-coil tubes, and a flue channel. The housing includes a burner, a water inlet, a water outlet and a flue gas outlet. The burner is disposed on a top portion of the housing and connected to an air/gas mixture unit. The first group of fin tubes is disposed tightly, circularly, and coaxially around the burner. The flue channel is disposed below the burner and is formed by a second group of fin tubes. A flow of flue gas vents from the flue channel to the flue gas outlet. The water inlet is connected to the first group of fin tubes which forms the flue channel below the burner. The second group of fin tubes below the burner is connected to the first group of fin tubes. The first group of fin tubes is connected to the water outlet.

Abstract: A forced convection fin tube condensing heat exchanger for supplying heat includes a shell, burner and fin tubes bundle. The burner is at the top of the shell, circular fin tubes bundle installed around the burner tightly, circularly and coaxially. The flue channel which is formed by the shell and a row of fin tubes bundle is below the burner. The flue flows along the flue channel to flue outlet. There are front and rear water manifolds at the two ends of the fin tubes. Water baffles inside the rear water manifold divide the rear water manifold into water inlet and outlet areas. The water enters the small portion of circular fin tubes bundle from water inlet area, through the front water manifold, back to the water outlet area via the main portion of the circular fin tubes bundle. The use of bended fin tube to improves efficiency.

Abstract: A heat exchanger for supplying heat includes a housing, a bundle of dual-ring, straight fin-coil tubes, and a flue channel. The housing includes a burner, a water inlet, a water outlet and a flue gas outlet. The burner is disposed on a top portion of the housing and connected to an air/gas mixture unit. The first group of fin tubes is disposed tightly, circularly, and coaxially around the burner. The flue channel is disposed below the burner and is formed by a second group of fin tubes. A flow of flue gas vents from the flue channel to the flue gas outlet. The water inlet is connected to the first group of fin tubes which forms the flue channel below the burner. The second group of fin tubes below the burner is connected to the first group of fin tubes. The first group of fin tubes is connected to the water outlet.