A heat exchanger includes a case, fins, and heat transfer tubes. Combustion exhaust gas passes downward in the case. The fins are disposed at a lower portion of the case and arranged in the first direction. Each of the fins includes a first end and a second end that is an opposite end from the first end in a second direction intersecting the first direction. Each of the fins includes through holes in which the heat transfer tubes are inserted. Each of the fins includes heat receiving portions arranged in the second direction and connecting portion connecting the heat receiving portions. The heat receiving portions include a first heat receiving portion disposed at the first end. The first heat receiving portion includes a first recessed portion recessed from an outer edge of an upper part of the first heat receiving portion.

A method for improving the efficiency of a fired heater without an air preheat system is described. The method involves the use of an additional outboard convection section which is separate from the regular convection section of the fired heater. The outboard convection section uses the boiler feed water or an alternate cold sink to reduce the temperature of the flue gas, thereby improving the efficiency.

A furnace with a condensing heat exchanger and a pH sensor, and a method of monitoring the furnace are provided. The furnace may include a condensate collector box and/or a condensate trap. At least one of the condensate collector box and/or the condensate trap may include pH sensor (e.g., disposed within the respective component). The pH sensor is configured to measure a pH level of the condensate from the condensing heat exchanger. The furnace may include a control board configured to receive the pH level from the pH sensor. The control board may be configured to trigger a notification and/or change the operation of the furnace (e.g., to dilute the condensate) based on the received pH level. The notification may include at least one of: an illumination of an indicator disposed on the furnace, and a transmission of a signal to a communicating device such as a thermostat.

A condensation tray for condensing tankless water heaters is disclosed. The tray can include a plurality of peaks and valleys. The peaks can divert condensate runoff from a secondary heat exchanger into the valleys so as to prevent the condensate from falling on a primary heat exchanger. The tray includes gas apertures that enable combustion gases to pass through the tray and across the secondary heat exchanger. Overhangs on the peaks can prevent the condensate from draining through the gas apertures.

A condensation tray for condensing tankless water heaters is disclosed. The tray can include a plurality of peaks and valleys. The peaks can divert condensate runoff from a secondary heat exchanger into the valleys so as to prevent the condensate from falling on a primary heat exchanger. The tray includes gas apertures that enable combustion gases to pass through the tray and across the secondary heat exchanger. Overhangs on the peaks can prevent the condensate from draining through the gas apertures.

A water heater system includes a tank for storing water; a flue assembly positioned within the tank, the flue assembly adapted to transfer heat from flue gases within the flue assembly to water in the tank; a burner in fluid communication with an inlet end of the flue assembly and operable in at least a high input mode and a low input mode to deliver the flue gases to the flue assembly, the exhaust assembly having a threshold temperature above which the exhaust assembly is not suitable; and an exhaust assembly including a fan, wherein at least in the low input mode, the flue gases condense in the flue assembly, and wherein operation of the fan reduces a temperature of the flue gases in the exhaust assembly to below the threshold temperature at least in the high input mode.

A water heater system includes a tank for storing water; a flue assembly positioned within the tank, the flue assembly adapted to transfer heat from flue gases within the flue assembly to water in the tank; a burner in fluid communication with an inlet end of the flue assembly and operable in at least a high input mode and a low input mode to deliver the flue gases to the flue assembly, the exhaust assembly having a threshold temperature above which the exhaust assembly is not suitable; and an exhaust assembly including a fan, wherein at least in the low input mode, the flue gases condense in the flue assembly, and wherein operation of the fan reduces a temperature of the flue gases in the exhaust assembly to below the threshold temperature at least in the high input mode.

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.

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.

A water heating device includes: a heat exchanger having a case to which heating air is supplied, and heat transfer pipes accommodated inside the case; and a straightening vane arranged on the downstream side in a heating air flow direction of the heat transfer pipes, and having a plurality of vent holes. The heat transfer pipe includes a plurality of pipe body portions that extend along a direction intersecting the heating air flow direction and approach the straightening vane. The plurality of vent holes are arranged so as to overlap the plurality of pipe body portions in the heating air flow direction.