A system and approach for developing a periodic water usage profile and demand for controlling a water heater. A mode may be selected for demand for a certain amount of water of a particular temperature range to be available for use from the water heater. Data on hot water usage may be collected and the usage profile and demand may be calculated from the data. The water heater may be programmed to operate in a certain fashion based on the usage profile and demand. A control knob may be on the water heater control to select a particular demand. Control of the water heater may be operated from a remote device connected in a wireless or wired fashion. An optimization program may be implemented in the control of the water heater for achieving one or more beneficial goals related to water heater performance and hot water production.

A heat pump may include a compressor configured to compress a refrigerant, a first temperature sensor configured to detect an outdoor temperature, a second temperature sensor provided in heating pipes connected to a heating device that performs indoor heating and configured to detect a temperature of fluid flowing through the heating pipes, an outdoor heat exchanger configured to perform heat exchange between outdoor air and a refrigerant, a third temperature sensor configured to detect a temperature of the outdoor heat exchanger, and a controller. The controller may be configured to: control power to a boiler and/or to the compressor based on sensing values of the first, second, and third temperature sensors, calculate an expected efficiency of the heat pump based on the sensing value of the first temperature sensor and an initial target temperature, and control power to the boiler based on the expected efficiency.

A hot water tank is provided. The hot water tank comprising: a tank which includes a bottom, a top, and sides therebetween to define an interior; a combustion chamber within the interior, proximate the bottom and sides, the combustion chamber terminating in a mouth where it connects to the side; a gas burner, which is a first heat source and is housed in the combustion chamber; a combustion fan located at the mouth of the combustion chamber and in gaseous communication with an ambient environment and the combustion chamber; a substantially spiral flue which extends upward through the interior and is in gaseous communication with the combustion chamber and a chimney, which is located proximate the top of the tank, such that in use flue gases travel from the combustion chamber upward to the chimney; a condensation trap, which is outside the tank and is in fluid communication with the combustion chamber or the flue proximate the combustion chamber; and a controller, the controller configured to control the burner.

A hot water tank is provided. The hot water tank comprising: a tank which includes a bottom, a top, and sides therebetween to define an interior; a combustion chamber within the interior, proximate the bottom and sides, the combustion chamber terminating in a mouth where it connects to the side; a gas burner, which is a first heat source and is housed in the combustion chamber; a combustion fan located at the mouth of the combustion chamber and in gaseous communication with an ambient environment and the combustion chamber; a substantially spiral flue which extends upward through the interior and is in gaseous communication with the combustion chamber and a chimney, which is located proximate the top of the tank, such that in use flue gases travel from the combustion chamber upward to the chimney; a condensation trap, which is outside the tank and is in fluid communication with the combustion chamber or the flue proximate the combustion chamber; and a controller, the controller configured to control the burner.

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.

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.

A method and system of providing hot water efficiently. A cost of heating a volume of water to a predetermined temperature in a first water heater is determined. A cost of transferring a volume of hot water from a second water heater of a network of interconnected water heaters to the first water heater is determined. Upon determining that the cost of transferring the volume of hot water from the second water heater is lower than the cost of heating the volume of water of the first water heater, the second water heater transfers at least part of the volume of hot water to the first water heater. Otherwise, the volume of water is heated to the predetermined temperature in the first water heater.

Embodiments described herein generally relate to a domestic hot water (DHW) preheater operable to supply domestic hot water to a structure and/or to preheat a cold return of a space heating system.

This invention provides an electronic control for combination (fuel-fired boiler and electric heat pump) building space and water heating systems that optimizes operation of such within the operating temperature limits and heat capability of both the heat pump and boiler unit in the combination system. In a diagnostic mode, the controller assesses the ability of existing heat radiation systems in thermostatically controlled zones to meet heating loads at different operating temperature limits of the heat pump and boiler. The system/controller provides information to guide most effective deployment of system heat-dissipation devices. In its normal operating mode, the controller is capable of receiving input signals from zone thermostats, the boiler and heat pump, along with current outdoor temperature and other data, processing and evaluating inputs over time, and outputting control signals. The controller facilitates use of a combined heat pump and boiler heating system with minimum equipment, installation, and operational cost.

Hot water heating system comprising one or more water heaters with at least one water heating mechanism, and a heating-control storage tank generally configured to store heated water in a temperature stratified manner where hotter water tends to be separated from cold water. The heating-control storage tank can receive thermal energy or hot water from the water heater, send thermal energy or water to the water heater as its makeup water, and provide hot water directly to end users. The water heater may or may not be used to provide hot water to end users. The system is electronically controlled using a processor, various sensors, a recirculation pump, and electronically actuated valves. Depending on hot water needs and energy costs, the system controls water heating schedule and amount of hot water stored in the heating-control storage tank by changing system operation modes to minimize energy costs while providing reliable service.