A premixing apparatus for mixing air with a fuel gas to supply a burner with an air-fuel mixture via a fan includes: a zero governor and a motor-driven type of variable throttle valve, both being disposed in a gas supply passage; and an excess air ratio detecting device for detecting an excess air ratio of the air-fuel mixture, thereby regulating an opening degree of the variable throttle valve so that the excess air ratio of the air-fuel mixture becomes a predetermined value. An arrangement is made to prevent an ignition failure from occurring in an attempt to perform an ignition operation in a state in which, due to a trouble with the variable throttle valve of remaining opened or remaining closed, the excess air ratio of the air-fuel mixture becomes too small or too excessive. The variable throttle valve is provided with a sensing device.

A fluid heating apparatus for heating fluid on a fluid path may comprise a fluid pump, a fluid heater, a temperature sensor to sense fluid temperature and generate a temperature signal, and a temperature control assembly configured to control the temperature of the fluid. The control assembly may comprise a target temperature input to receive a target temperature, a pump control to control operation of the fluid pump to control a flow rate of the fluid, and a heater control to control operation of the fluid heater to control a degree of heat output by the fluid heater. The temperature control assembly may be configured to increase and decrease fluid flow along the fluid path and to increase and decrease heat output of the fluid heater to control the temperature of the fluid at the fluid outlet.

A device for producing and treating a gas stream is provided that includes an enclosure, of which the lower part is submerged in a liquid supply open at the top and includes at least one liquid intake opening. The submerged lower part of the enclosure contains a volume of this liquid and at least one opening for discharging a gas stream, positioned above the surface of the volume of liquid contained in the enclosure. The device further provides for injecting a gas stream including at least one injection conduit and extends in the upper part inside the enclosure outside the volume of liquid. During operation of the device an incoming gas stream is introduced to create an outgoing gas stream, treated by direct contact with said volume of liquid that is discharged outside the enclosure. A facility inclusive of the device and method of operation are also provided.

A fluid heater for heating fluid moving along a fluid path between a fluid inlet and a fluid outlet. The fluid heater comprises a fluid preheating assembly configured to directly heat fluid moving along the fluid path, a fluid holding tank for receiving preheated fluid moving along the fluid path from the fluid preheating assembly, a primary fluid pump configured to pump fluid along the fluid path, and a primary fluid heating assembly configured to indirectly heat fluid moving along the fluid path from the fluid holding tank. Fuel is combusted in the primary fluid assembly and an exhaust gas movement path is defined to guide the exhaust gas from the primary fluid heating assembly through the fluid holding tank to the fluid preheating assembly.

A device for producing and treating a gas stream is provided that includes an enclosure, of which the lower part is submerged in a liquid supply open at the top and includes at least one liquid intake opening. The submerged lower part of the enclosure contains a volume of this liquid and at least one opening for discharging a gas stream, positioned above the surface of the volume of liquid contained in the enclosure. The device further provides for injecting a gas stream including at least one injection conduit and extends in the upper part inside the enclosure outside the volume of liquid. During operation of the device an incoming gas stream is introduced to create an outgoing gas stream, treated by direct contact with said volume of liquid that is discharged outside the enclosure. A facility inclusive of the device and method of operation are also provided.

An automated descaling system can be integrated into a tankless water heater or can be a separate system that is connected to a tankless water heater. The automatic descaling system comprises a cleaning media chamber and a valve with a motor. The descaling system can be set on an automatic cleaning schedule.

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 heat exchanger and a water heater are provided. The heat exchanger is provided with an auxiliary member including a trunk pipe joint portion joined to a trunk pipe and an extension portion extending from the trunk pipe joint portion toward a plurality of fins. The plurality of fins is provided apart from a sidewall portion so as not to directly contact the sidewall portion of a case, the extension portion of the auxiliary member includes an entry portion that enters between the plurality of fins and the sidewall portion, and a first abutment portion which is provided in the entry portion and abuts outer end portions of the plurality of fins, the first abutment portion is separated from the sidewall portion, and a space portion in which inflow of the heating gas is suppressed is formed between the first abutment portion and the sidewall portion.

A hot water supply device includes: a combustion part including a first burner part for which a flame sensor is disposed and a second burner part having a different number of burners from the first burner part such that one or both of the burner parts perform combustion, the flame sensor being configured to detect combustion state information of a flame generated by burners; a combustion control part configured to monitor a combustion mode of the combustion part set in accordance with a hot water supply request and change a second combustion mode in which the first burner part does not perform combustion, to a first combustion mode in which at least the first burner part performs combustion, when the second combustion mode is continuing; and a combustion adjustment control part configured to execute a combustion adjustment process of the combustion part.

A heat exchanger includes front and rear walls forming a flue gas space such that a fluid flowing through a channel formed in the front and rear walls can exchange heat with flue gas in the flue gas space, in use. An entirety of the back wall extends along a first plane, and the back wall is provided with a back fin. The front wall includes a lower portion extending upwardly along the back wall, and an upper portion extending upwardly from an upper end of the lower portion and outwardly away from the back wall to form a combustion space of a flammable gas between the upper portion and the back wall. The upper portion is provided with a front fin. The front and back fins are arranged symmetrically with respect to a virtual line along which the flammable gas is to be injected into the combustion space.