Provided is a gas furnace including a primary heat exchanger and a secondary heat exchanger through which a combustion gas produced by the combustion of a fuel gas flows. The gas furnace includes: a coupling box serving as an intermediary to connect the primary heat exchanger and the secondary heat exchanger; a collect box connected to the secondary heat exchanger, for letting in the combustion gas passed through the secondary heat exchanger; an inducer connected to the collect box, for inducing a flow of the combustion gas; and a bypass pipe connected to one side of the coupling box and including a bypass pipe for guiding the combustion gas passed through the primary heat exchanger to a hot water supply tank for supplying hot water to an indoor space.

The disclosed technology includes a system and method of preventing short cycling in a water heater. The system can include a burner, a temperature sensor, and a controller. The controller can be configured to perform several steps to determine whether to turn on a burner and whether to increment a temperature offset value based on the amount of time that has elapsed since the last time the burner was on.

Control of temperature of water delivered by a dual-stage water heater having an external boiler with a first heater as first stage and an internal duct (water booster) with a second heater as second stage. A control loop based on a measured water temperature in the boiler and controls the first heater. A second loop calculate a reference booster water temperature based on the temperature error at the outlet (difference between a measured outlet water temperature and a reference outlet water temperature) and controls second heater based on error between reference booster water temperature and measured booster water temperature. The reference outlet water temperature depends on type of beverage (e.g. espresso, cappuccino) and includes a temperature profile with different temperature for different sub-beverages (e.g. coffee, milk). Takes into account physical response times, inertia of heater and anticipate sudden changes of reference water temperature at hot water outlet.

The disclosed technology includes systems and methods for operating a pool water heating system. The pool water heating system can include a heat pump, a supplemental heat source, a water temperature sensor, and a controller. The controller can be configured to receive water temperature data and, in response to determining that the temperature of the water is less than a threshold temperature, output a control signal to activate the heat pump. The controller can further determine an expected heating time that can be indicative of an amount of time required for the temperature of the water to be greater than or equal to the threshold temperature. The controller can also generate a heating schedule based at least in part on the expected heat time and a predetermined time of use. The heating schedule can be indicative of a heat pump operation time and a supplemental heat source operation time.

A safety system and method to prevent water within a top portion of a tank of an electric water heater to drop below a safe temperature during a load shedding period, other than a full emergency grid failure, by a power provider whereby to prevent the propagation of harmful bacteria in a top portion the tank. A control device monitors the water temperature in the top portion of the tank by the use of a temperature sensor. If the control device detects a temperature of the water in the top portion of the tank inferior to 140 degrees F., it will by-pass the instructions of the power provider and connect power to one or more of the resistive heating elements of the tank until a predetermined temperature above 140 degrees F. is attained before switching off the resistive heating elements.

A water heating tank is provided comprising a reservoir with a cold water inlet into the reservoir and a hot water outlet from the reservoir. The water heating tank further comprises a heater enclosure located within the reservoir. The heater enclosure encloses at least part of a heater. The heater enclosure has an inlet, a vent and an outlet. The water heating tank further comprises a duct connected to the outlet of the heater enclosure. The duct has an exit located in an upper portion of the reservoir.

A method of controlling a gas powered water heater includes attempting to pick a main gas valve of the main burner using a first pick method. The first pick method includes closing a switch of a valve pick system to couple a capacitor of the valve pick system to the main gas valve for a first length of time to discharge energy stored in the capacitor to the main gas valve, and opening the switch of the valve pick system after the energy stored in the capacitor is discharged to the main gas valve. The controller determines if the main gas valve is open after using the first pick method. When the controller determines the main gas valve is not open, the controller attempts to pick the main gas valve using a second pick method different than the first pick method.

A heat distribution system, method and computer program product, including an unpressurized tank configured for holding a heat transfer fluid; and one or more submersible heat transfer fluid pumps configured to pump the heat transfer fluid to one or more heat load loops respectively connected to the one or more heat transfer fluid pumps.

A heat pump water heater and systems and methods for its control. The systems are configured to heat water within a water storage tank of a heat pump water heater wherein a controller within the system is operatively connected to a plurality of heat sources including at least one electric heating element and a heat pump and sensors in order to selectively energize one of the plurality of heat sources. The controller is configure to process data representative of the temperature of water within the tank near the top of the water storage tank, and rate of water flowing out of the water storage tank, in order to automatically selectively energize the heat sources. The selection of heat sources by the controller is determined by a mode of operation selected by the user and the data processed by the controller in view of the selected mode of operation.

Provided is a fuel cell system. The fuel cell system comprises: a reformer that reforms fuel; a reformed fuel storage unit that receives the reformed fuel from the reformer and stores same; a fuel cell stack that generates electric power and heat by using the reformed fuel; a boiler unit that provides heating by using heating water, a battery unit that stores the electric power generated in the fuel cell stack; and a control unit that controls the operations of the reformer, the reformed fuel storage unit, the fuel cell stack, the boiler unit, and the battery unit, wherein the control unit controls the reformer to operate using the heating water of the boiler unit when the temperature of the heating water of the boiler unit is higher than a first baseline and the stored amount of the reformed fuel stored in the reformed fuel storage unit is equal to or less than a second baseline.