A hot water supply device including an inlet pipe, an outlet pipe, a burner unit, a heat exchanger, an exhaust aperture, a first temperature sensor detecting a measured exhaust temperature of the exhaust gas, a second temperature sensor detecting a water temperature of water entering the inlet pipe, and a processor. The processor is configured to obtain an error between the measured exhaust temperature and an estimated exhaust temperature, and detects that scale clogging has occurred inside the heat exchange tubing based on an index which is generated using the error between the measured exhaust temperature and the estimated exhaust temperature. The estimated exhaust temperature is a first predetermined value that is determined using a numerical equation which has at least the water temperature of water entering the inlet pipe and a scale number of the hot water supply device as variables of the numerical equation.

A hot water supply apparatus has: a thermo-sensitive valve which is connected in parallel to a cold water delivery pipe and a hot water delivery pipe and which is closed when the hot water temperature to flow inside the valve is above a predetermined temperature to thereby shut off communication between the cold water delivery pipe and the hot water delivery pipe; and a circulation pump. By operation of the circulation pump, water circulation takes place from a heat exchanger through the hot water delivery pipe, a return pipe, the circulation pump, and a cold water supply pipe back to the heat exchanger. When the thermo-sensitive valve is open, water circulation takes place also through the thermo-sensitive valve. Instantaneous hot water supply operation is finished when an amount detected by a flow sensor falls below a predetermined amount during the instantaneous hot water supply operation.

In a heat source apparatus in which an electric component having an electrode and an insulator is mounted on a side plate of a combustion box, in a state in which a packing is interposed between a flange portion of the insulator and the side plate, by fastening a clamp which overlaps with an outer surface of the flange portion, to the side plate, the temperature rise in the clamp is restrained.

Upper and lower water tubes constituting a part of a water jacket are disposed on the side plate on upper and lower sides of the position of mounting the electrode component. In case the upper and lower water tubes are disposed on an inside surface of the side plate, the upper and lower parts of the clamp are brought into contact with those disposed positions of the water tubes which are in upper and lower portions of the side plate and, in case the upper and lower water tubes are disposed on an outside of the side plate, the upper and lower parts of the clamp are brought into contact with the upper and lower water tubes.

In a heat source apparatus in which an electric component having an electrode and an insulator is mounted on a side plate of a combustion box, in a state in which a packing is interposed between a flange portion of the insulator and the side plate, by fastening to the side plate a clamp which overlaps with an outer surface of the flange portion, the packing is prevented from getting spread when compressed, thereby securing good sealing properties.

Upper and lower water tubes constituting a part of a water jacket are disposed on a side plate on upper and lower sides of the mounting position of the electrode component. In case the upper and lower water tubes are disposed on an inside surface of the side plate, upper and lower side edge portions of the packing are in contact with those upper and lower swelled-out portions formed in the one-side side plate which are swollen outward for respectively receiving into recesses the upper and lower water tubes; and that, in case the upper and lower water tubes are disposed on an outside surface of the side plate, upper and lower side edge portions of the packing are in contact with the upper and lower water tubes.

A fluid heater for a heating fluid and having a fluid inlet and a fluid outlet may comprise a heater housing defining an interior with a combustion chamber being positioned in the interior of the housing, and fluid tubing in the interior of the housing and adjacent to the combustion chamber, with the fluid tubing defining a fluid path through the housing between the fluid inlet and the fluid outlet. The heater may also include a burner configured to combust a fuel in the combustion chamber to heat the fluid tubing. At least a portion of the fluid path may comprise a bifurcated fluid path between the fluid inlet and the fluid outlet.

A combustion apparatus includes a burner (11), a heat exchanger (12) accommodated in a casing (20), an exhaust passage (22B) provided to one side surface side of the casing (20), and an exhaust resistance member (5) having a plurality of ventilation ports (50) through which combustion exhaust gas passes, wherein at least one part of the ventilation ports (50) has an elongated hole shape extending in the flow direction of the combustion exhaust gas from beneath the casing (20) to the exhaust passage (22B).

A water heater includes a primary heat exchanger, a secondary heat exchanger disposed above the primary heat exchanger, a flow path member, and a flow restriction member. The secondary heat exchanger includes a case and heat transfer pipes arranged in the case. The case includes a wall having a gas inlet through which combustion exhaust gas discharged from the primary heat exchanger is introduced into the case. The flow path member connects the primary heat exchanger and the secondary heat exchanger and is disposed adjacent to the gas inlet and is configured to introduce the combustion exhaust gas discharged from the primary heat exchanger into the secondary heat exchanger through the gas inlet. The flow restriction member is disposed on the wall of the case to suppress upward flowing of the combustion exhaust gas that is introduced into the case through the gas inlet.

System and methods for controlling operating state of a heat transfer system are disclosed herein. The heat transfer system can include temperature sensor positioned at the fluid inlet line and the fluid outlet line and a heat exchanger between the fluid inlet line and the fluid outlet line. The heat transfer system can include a processor communicatively coupled to the first temperature sensor and the second temperature sensor. The processor can determine an inlet temperature of water flowing in the fluid inlet line and outlet temperature of water flowing in the fluid outlet line and can determine a delta temperature based on difference between the inlet temperature and the outlet temperature. Based on the inlet temperature and the delta temperature, the processor can determine an operating state of the heat transfer system.

A heat exchanger having a first heat exchanger tube and a second heat exchanger tube is disclosed. The first heat exchanger tube can have a first leg, a second leg, and a bend section, and the bend section of the first heat exchanger tube can include three or more bends, each of the three or more bends having a corresponding bend angle that is less than or equal to approximately 90 degrees. The second heat exchanger tube can have a first leg, a second leg, and a bend section, and the bend section of the second heat exchanger tube can include three or more bends, each of the three or more bends having a corresponding bend angle that is less than or equal to approximately 90 degrees.

A water heater is provided that can suppress backflow (entry) of drainage water into a fan from downstream of the fan in a path of a flow of combustion gas. The fan includes a fan case, an impeller housed within the fan case, a drive source attached to the fan case so as to drive the impeller, and a rotation shaft connecting the impeller and the drive source. An exhaust connection portion has a connection portion case and is provided with an exhaust port for emitting combustion gas delivered from the fan to outside of the water heater. The exhaust connection portion also has a drainage water discharge portion for discharging drainage water accumulated downstream of the fan in the path of the flow of combustion gas.