A water heater is provided that heats water in a storage tank and discharges the heated water. The water heater includes a storage tank configured to store water, at least one first temperature sensor configured to sense a temperature of the water stored in the storage tank, a second temperature sensor configured to sense a temperature related to an outside of the water heater, a first heat exchanger comprising at least one heating element configured to heat the water, a second heat exchanger comprising a heat pump system and configured to heat the water, and a controller configured to control at least one of the first heat exchanger and the second heat exchanger based on a temperature sensed by the second temperature sensor and a set water temperature.

A heat pump may include a compressor configured to compress a refrigerant, a first temperature sensor provided in heating pipes connected to a heating device that heats an indoor space to sense a temperature of fluid flowing through the heating pipes, and a controller. The controller may be configured to determine whether a boiler is operating to heat an indoor space or is operating to supply hot water based on a sensing value of the first temperature sensor. The compressor may operate when the controller determines that the boiler is not operating to heat the indoor space and/or determines that the boiler is operating to supply hot water.

A solar photovoltaic (PV) water heating system includes a tank (1.020) including at least a first heating unit (1.016) having at least first and second heating elements (1.016.1 . . . 1.016.x), at least one of which is switchable (1.014.1A . . . 1.014.1m); a PV solar collector (1.002); an inverter (1.004) adapted to convert the output from the PV collector to an alternating power supply; a modulator (1.060) to modulate the alternating power supply from the inverter; a controller (1.040) adapted to control the modulator and the switching of the or each switchable heating element; wherein the controller is adapted to control the modulator and the switchable heating elements to maximize the energy drawn from the PC collector.

A CHP optimal dispatching model is a mixed integer programming model and is used for a district heating system (DHS) comprising a heat source, a heating network and a heat load, and the heating network comprises a heat transmission network and a heat distribution network. A plurality of heating areas is divided, and one day is divided into a plurality of time periods; the heat transmission loss of the heat distribution network is omitted, and a heat transmission network model taking transmission time delay of the heating network into consideration is established according to the heat transmission network; a terminal heat consumer model capable of reflecting indoor temperature is established; and a combined optimal dispatching model comprising conventional generators, wind power units, CHP units, electric boilers and heat storage tanks is established.

A thermally enhanced heating system and a method for thermally enhancing a HVAC system are provided. The thermally enhanced heating system preferably includes an outdoor HVAC unit and an indoor HVAC unit. The indoor HVAC unit includes a first heat exchanger for transferring heat from a refrigerant, a second heat exchanger for transferring heat from a fuel source, and a third heat exchanger for transferring heat to the refrigerant. The outdoor HVAC unit includes an outdoor heat exchanger for transferring heat from an outdoor air to the refrigerant, a pump configured to circulate the refrigerant, and an ejector configured to combine the refrigerant from the outdoor heat exchanger and the third heat exchanger. Preferably the outdoor HVAC unit is operated to circulate the refrigerant through a first refrigerant circuit and a second refrigerant circuit, and combine refrigerant in the first refrigerant circuit and the second refrigerant circuit.

A solar photovoltaic (PV) water heating system includes a tank including at least a first heating unit having at least first and second heating elements, at least one of which is switchable; a PV solar collector; an inverter adapted to convert the output from the PV collector to an alternating power supply; a modulator to modulate the alternating power supply from the inverter; a controller adapted to control the modulator and the switching of the or each switchable heating element; wherein the controller is adapted to control the modulator and the switchable heating elements to maximize the energy drawn from the PV collector.

A water heater can include a tank, an inlet line, and an outlet line, where the inlet line provides unheated water to the tank, and where the outlet line draws heated water from the tank for a hot water demand. The water heater can also include a heat pump disposed adjacent to a first portion of the tank, where the heat pump applies heat to transform the unheated water to heated water in the first portion of the tank. The water heater can further include a resistive heating element disposed within a second portion of the tank, where the resistive heating element further applies heat to transform the unheated water to heated water in the second portion of the tank.

A water-heating system, including: a controller; a refrigerant-water heat exchanger for exchanging heat between refrigerant and water; a sensor circuit for measuring a current water temperature of water in a water heater and providing the current water temperature to the controller; a first refrigerant pipe for passing the refrigerant from a refrigerant source to the refrigerant-water heat exchanger; a second refrigerant pipe for passing the refrigerant from the refrigerant-water heat exchanger to the refrigerant source; a first water pipe for passing the water from the water heater to the refrigerant-water heat exchanger; a second water pipe for passing the water from the refrigerant-water heat exchanger to the water heater; and a water pump for pumping water from the water heater to the refrigerant-water heat exchanger via the first water pipe and from the refrigerant-water heat exchanger to the water heater via the second water pipe based on a control signal.

An air conditioning system having an auxiliary heat source is provided and that may include an outdoor unit, an indoor heat exchanger connected to the outdoor unit, the indoor heat exchanger including a temperature sensor, an auxiliary heat source arranged as an auxiliary to the outdoor unit and operated by an energy source different from an energy source of the outdoor unit, a thermostat configured to control a temperature of an installation space supplied with cold air or warm air by the outdoor unit and the auxiliary heat source, and a communicator. The communicator may include an input unit connected to the thermostat, a first output unit connected to the auxiliary heat source, a second output unit connected to the outdoor unit, and a controller configured to process signals between the input unit, the first output unit, and the second output unit.

A gas-fired instantaneous water heater including a thermoelectric generator (TEG) and a heat pump that is powered by the TEG to improve efficiency compared to existing water heaters. Water to be heated is circulated through the heat pump, TEG heat exchanger, and primary heat exchanger to produce a stream of heated water. An adjustable firing rate permeable matrix radiant burner is included, in which natural gas and air are combusted to produce combustion products, including heat. The combustion products are condensed in a condensing system to produce cooled and dry exhaust gas.