A gas valve for a gas appliance of a gas burner system. The gas valve is connected to a gas source via a gas pipe. The gas valve is disposed with a check valve body, wherein the check valve body allows gas in the gas pipe to flow into the gas valve and prohibits the gas in the gas valve to flow into the gas pipe so the check valve body can thereby prevent the gas in the gas valve from flwoing back to the gas pipe. When gas in the gas pipe flows to to another gas appliance of the gas burner system, the gas flowing to another gas appliance does not mix with air in the gas appliance, thereby reducing the iginition time and enhancing the combustion efficiency.

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 connected-type hot-water supply system includes hot-water supply apparatuses connected in parallel and a control means. The control means sets one main hot-water supply apparatus and sub-hot-water supply apparatuses, and performs leveling control of cumulative loads of the hot-water supply apparatuses by setting the main hot-water supply apparatus based on sequential rotation among the hot-water supply apparatuses. The control means includes a failure sign response mode in which it is determined whether there is a failure sign respectively for components of the hot-water supply apparatuses, and when a component of a part of hot-water supply apparatuses is a failure sign component determined to have a failure sign, a main use time of a hot-water supply apparatus having the failure sign component is increased, and the main use time is a main use time of serving as the main hot-water supply apparatus in the leveling control.

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.

System and method for grid load-up dual set point. The invention provides a method of operating a water heater having a tank configured to store water. The method includes heating, via a first heating element, a first portion of the water to a first temperature set point. The method also includes heating, via a second heating element, a second portion of the water to a second temperature set point, the second temperature set point being greater than the first temperature set point. The method additionally includes receiving a load-up signal from a grid controller, and heating, via the first heating element, the first portion of the water to the second temperature set point upon receiving he load-up signal.

An aircraft water supply system supplies water to a water discharge port in an aircraft. A cold water flow path supplies cold water to the water discharge port. A hot water flow path supplies hot water to the water discharge port. A first control valve adjusts the flow rate of cold water flowing through the cold water flow path. A second control valve adjusts the flow rate of hot water flowing through the hot water flow path. A temperature sensor detects the water temperature at any point up to the water discharge port. A flow control unit controls the opening/closing state of the first control valve and the second control valve based on the water temperature detected by the temperature sensor.

A water heater system having a running water inlet through which running water flows in and a hot water outlet through which hot water heated in a heat exchanger is discharged is disclosed. The water heater system may include a first connection pipe connecting a gap between the running water inlet and an entry of the heat exchanger, a second connection pipe connecting a gap between an outlet of the heat exchanger and the hot water outlet; a bypass pipe connecting a gap between the first connection pipe and the second connection pipe, a bypass valve installed to the bypass pipe so as to control the direction of water flowing through the bypass pipe, and a controller, in a hot water usage mode, controlling the bypass valve so that the water moves from the first connection pipe to the second connection pipe through the bypass pipe, and in an inner circulation mode, controlling the bypass valve so that the water moves from the second connection pipe to the first connection pipe through the bypass pipe.

A combined hot water and air heating and conditioning system including a first heat exchanger, a heat pump, a chilling tower loop, a burner and a second heat exchanger to provide hot water, air heating and air cooling. The system provides hot water, air heating and cooling all in one single unit. The system utilizes a heat pump to remove heat from ambient air and transfer the rejected heat into a hot water system, thereby using waste heat to heat the hot water system. The system utilizes a heat exchanger not only for the purpose of transferring heat from a heating source to a fluid in the heat exchanger but also for the purpose of dissipating heat from the fluid in the heat exchanger to the surroundings of the heat exchanger, thereby allowing a heat pump to act both as an air heating and conditioning device.

A connected-type hot-water supply system includes hot-water supply apparatuses connected in parallel and a control means. The control means sets one main hot-water supply apparatus and sub-hot-water supply apparatuses, and performs leveling control of cumulative loads of the hot-water supply apparatuses by setting the main hot-water supply apparatus based on sequential rotation among the hot-water supply apparatuses. The control means includes a failure sign response mode in which it is determined whether there is a failure sign respectively for components of the hot-water supply apparatuses, and when a component of a part of hot-water supply apparatuses is a failure sign component determined to have a failure sign, a main use time of a hot-water supply apparatus having the failure sign component is increased, and the main use time is a main use time of serving as the main hot-water supply apparatus in the leveling control.

A tankless water heater, comprising: a flow channel with a cold-water inlet pipe, a heating unit with an heating element configured to heat water flowing through the heating unit and a hot-water outlet pipe, and a control unit configured to control the tankless water heater, wherein the control unit is configured to receive a power limitation signal of an external facility management system and to control a heating output of the heating element depending on the power limitation signal.