A method for controlling an on-demand high volume capable fluid heating system that supplies a total heating power at a turndown ratio and a total flowrate of a fluid supply, the fluid heating system comprising a plurality of heat exchangers fluidly connected in parallel, each of the plurality of heat exchangers comprising: a fluid conductor, wherein each of the plurality of heat exchangers contributes to the total heating power and a portion of the total flowrate of the fluid supply through the fluid conductor; an inlet conductor configured to connect the fluid supply to the plurality of heat exchangers; an outlet conductor configured for receiving the fluid supply downstream of the plurality of heat exchangers; an auxiliary conductor connecting the inlet conductor at a first location and the outlet conductor, the auxiliary conductor comprising a modulating valve; and a pump disposed downstream from the first location on the inlet conductor.

A combination boiler provides heated water to a boiler loop and domestic hot water (DHW) to a domestic water loop. The combination boiler includes a primary heat exchanger (PHE) connected to the boiler loop and a burner to provide heat to the primary heat exchanger. A secondary heat exchanger (SHE) transfers heat energy from the boiler loop to the domestic water loop. A controller monitors a PHE inlet temperature and a DHW output temperature, obtains a pre-heat initialization temperature threshold and a pre-heat cancellation temperature threshold, and detects a low temperature condition. A pre-heat operation is initiated responsive to the low temperature condition by circulating heated water from the PHE to the SHE. The burner is selectively fired at least in part according to an outlet temperature of the PHE.

A combination boiler provides heated water to a boiler loop and domestic hot water (DHW) to a domestic water loop. The combination boiler includes a primary heat exchanger (PHE) connected to the boiler loop and a burner to provide heat to the primary heat exchanger. A secondary heat exchanger (SHE) transfers heat energy from the boiler loop to the domestic water loop. A controller monitors a PHE inlet temperature and a DHW output temperature, obtains a pre-heat initialization temperature threshold and a pre-heat cancellation temperature threshold, and detects a low temperature condition. A pre-heat operation is initiated responsive to the low temperature condition by circulating heated water from the PHE to the SHE. The burner is selectively fired at least in part according to an outlet temperature of the PHE.

The present invention provides a combined heating and hot-water boiler for heating and hot-water. The combined heating and hot-water boiler comprises: a main heat exchanger which heats heating water through heat exchange; a hot-water heat exchanger to which the heating water heated by the main heat exchanger is supplied, and which heats tap water into hot water through heat exchange with the heating water; and a control unit which controls the flow of the heating water having passed through the hot-water heat exchanger to control the formation of at least one of a first flow path for supplying, to an object to be heated, the heating water having passed through the hot-water heat exchanger, and a second flow path for supplying, to the main heat exchanger, the heating water having passed through the hot-water heat exchanger.

A water heater system includes a water heater having a first water outlet and a second water outlet. The water heater system further includes a flow detection device coupled to the first water outlet to detect a water flow through the first water outlet. The water heater system also includes a flow control valve fluidly coupled to the second water outlet. The flow control valve is configured to control a flow of water through the second water outlet based on whether the water flow through the first water outlet is detected by the flow detection device.

A water heater system includes a water heater having a first water outlet and a second water outlet. The water heater system further includes a flow detection device coupled to the first water outlet to detect a water flow through the first water outlet. The water heater system also includes a flow control valve fluidly coupled to the second water outlet. The flow control valve is configured to control a flow of water through the second water outlet based on whether the water flow through the first water outlet is detected by the flow detection device.

A district energy distributing system is disclosed. The system comprises a geothermal heat source system comprising a geothermal heat source and a feed conduit for a flow of geothermally heated water from the geothermal heat source. The system further comprises a district feed conduit, a district return conduit and a plurality of local heating systems, each having an inlet connected to the district feed conduit and an outlet connected to the district return conduit, wherein each local heating system is configured to provide hot water and/or comfort heating to a building, A central heat exchanger is connected to the feed conduit of the geothermal heat source system such that an incoming flow of geothermally heated water is provided to the central heat exchanger.

Disclosed is a two-stage heating geothermal system using geothermal energy. The two-stage heating geothermal system includes a geothermal heat exchanger, a geothermal heat pump, a booster heat pump, a bypass line, and a bypass line opening and closing valve. The operating efficiency of the two-stage heating geothermal system using geothermal energy is significantly improved. Hot water supply, auxiliary heating, and the like are controlled to be completely independent of main heating.

A waste heat recovery device with a first heat medium side inlet; a first heat medium side outlet; a first heat medium flow path; a second heat medium side inlet; a second heat medium side outlet; a second heat medium flow path; a heat exchanger that exchanges heat between the first heat medium and second heat medium; an expansion tank in the first heat medium flow path; a bypass flow path that causes the first heat medium to flow and bypass the heat exchanger; and a mixer where the bypass flow path and first heat medium flow path merge together. The mixer is configured to adjust a ratio of a flow rate of the first heat medium in the bypass flow path and a flow rate of the first heat medium in the heat exchanger, such that the temperature of the first heat medium after merging approaches a predetermined temperature.

A regulating method for a heating and/or cooling system uses at least one load circuit (6), through which a fluid as a heat transfer medium flows and switches the at least one load circuit (6) on and off in dependence on a room temperature in a room to be thermally regulated by the at least one load circuit (6). A feed temperature (T.sub.mix) of the fluid fed to the at least one load circuit (6) is set in dependence on the relative switch-on duration (D) of the at least one load circuit (6). A manifold device is also provided for a heating and/or cooling system with a control device for carrying out such a regulating method.