A heating system (100), a controller (110) for a heating system and a method of controlling a heating system (100) suitable for responding to grid stress events are disclosed. A heating system (100) comprises a tank (104) for holding water; a heat pump (102) arranged to provide heat to the tank (104); an electric heating element (108) disposed in the tank for heating water; and, a controller (110) configured to: control electric power from an electric power grid to the heat pump (102) and the electric heating element (108); detect a grid stress event; determine a heat pump energy penalty for providing heat in response to the grid stress event under a present operating condition; and, vary, in dependence on the determined heat pump energy penalty, a power provided to the electric heating element (108).

A heat-pump circuit may include an indoor heat exchanger, an outdoor heat exchanger, a compressor adapted to circulate a working fluid between the indoor and outdoor heat exchangers, and an expansion device disposed between the indoor and outdoor heat exchangers. A monitor for the heat-pump system may include a return-air temperature sensor, a supply-air temperature sensor, and a processor. The return-air temperature sensor may be adapted to measure a first air temperature of air upstream of the indoor heat exchanger. The supply-air temperature sensor may be adapted to measure a second air temperature of air downstream of the indoor heat exchanger. The processor may be in communication with the return-air temperature sensor and the supply-air temperature sensor. The processor may be programmed to determine a working-fluid-charge condition of the heat-pump system based on the first and second air temperatures.

A method of and system for heating and/or cooling a fluid, the method comprising moving the fluid through a secondary side of a heat exchanger and controlling the temperature of a primary side of the heat exchanger such that the temperature of the primary side of the heat exchanger is maintained substantially at a determined temperature interval from a reference temperature which is a function of at least one of: a temperature of an inlet to the secondary side and a temperature of an outlet of the secondary side.

A heat-pump circuit may include an indoor heat exchanger, an outdoor heat exchanger, a compressor adapted to circulate a working fluid between the indoor and outdoor heat exchangers, and an expansion device disposed between the indoor and outdoor heat exchangers. A monitor for the heat-pump system may include a return-air temperature sensor, a supply-air temperature sensor, and a processor. The return-air temperature sensor may be adapted to measure a first air temperature of air upstream of the indoor heat exchanger. The supply-air temperature sensor may be adapted to measure a second air temperature of air downstream of the indoor heat exchanger. The processor may be in communication with the return-air temperature sensor and the supply-air temperature sensor. The processor may be programmed to determine a working-fluid-charge condition of the heat-pump system based on the first and second air temperatures.

When a heating operation mode using a heating unit is specified and when a hot water supply request using the hot water in a hot water storage tank does not occur, an air conditioning apparatus transmits a first selection signal for selecting the heating unit to a three-way valve. When the heating operation mode is specified and when the hot water supply request occurs, the air conditioning apparatus transmits, to the three-way valve, a second selection signal for changing a destination of circulation of secondary refrigerant from the heating unit to a coil heat exchanger, and transmits an operation start signal to a refrigerant indoor unit.

A hydronic system and method of use that will maintain normal system operating pressure while also reliably detecting even very small fluid losses in any closed loop fluid heat transfer system is described. The system includes a controller having clock or timing functionality in communication with one or more pressure sensors and a fluid supply valve that provides one or more notifications when the pressure drops below predetermined levels during predetermined periods of time. Depending on the nature of the pressure loss, the system has the capability of opening a fluid supply valve to provide make up fluid and increase system pressure.

Heat pump system (100) comprising a heat medium circuit (210,220,230,240,250,310,320,410,420,430,440,450,460) in turn comprising at least three heat exchanging means (314,315,315,422,433,452) between the heat medium and a respective heat source or sink selected from outdoor air, a water body, the ground, indoorair, pool water or tap water, a valve means (311,312,313,421,431,451) arranged to selectively direct the heat medium to at least two of said heat exchanging means, and a control means (500). The invention is characterized in that the heat pump system comprises temperature sensors (314a,314b;315a,315b;316a,316b;423,424,425;432,434,435) both upstream and downstream of at least one of said heat exchanging means, in that the system determines, based upon temperature measurement values comprising at least onevalue read from said sensors, to what heat exchanging means the heat medium is to be directed, and in that when heat medium is not directed to a certain heat exchanging means a measured temperature value is read upstream and downstream of the certain heatexchanging means, and in that an alert is set off in case the values differ by more than a predetermined value. The invention also relates to a method.

A storage type hot water supplying apparatus includes: a condenser having a refrigerant passage located at a hot water storage tank, the condenser being configured to condense refrigerant by exchanging heat between the refrigerant compressed by a compressor and water in the hot water storage tank; control circuitry configured to control a hot water storage operation, and a hot water supply detection sensor capable of detecting that a hot water supply operation is started, the hot water supply operation being an operation in which hot water in the hot water storage tank flows out of the hot water outlet and water flows into the hot water storage tank from the feed water inlet. The control circuitry is configured to increase an opening degree of the expansion valve when the hot water supply operation is started during the hot water storage operation.

A storage type hot water supplying apparatus includes: a condenser having a refrigerant passage located at a hot water storage tank, the condenser being configured to condense refrigerant by exchanging heat between the refrigerant compressed by a compressor and water in the hot water storage tank; control circuitry configured to control a hot water storage operation, and a hot water supply detection sensor capable of detecting that a hot water supply operation is started, the hot water supply operation being an operation in which hot water in the hot water storage tank flows out of the hot water outlet and water flows into the hot water storage tank from the feed water inlet. The control circuitry is configured to increase an opening degree of the expansion valve when the hot water supply operation is started during the hot water storage operation.

A heat-pump circuit may include an indoor heat exchanger, an outdoor heat exchanger, a compressor adapted to circulate a working fluid between the indoor and outdoor heat exchangers, and an expansion device disposed between the indoor and outdoor heat exchangers. A monitor for the heat-pump system may include a return-air temperature sensor, a supply-air temperature sensor, and a processor. The return-air temperature sensor may be adapted to measure a first air temperature of air upstream of the indoor heat exchanger. The supply-air temperature sensor may be adapted to measure a second air temperature of air downstream of the indoor heat exchanger. The processor may be in communication with the return-air temperature sensor and the supply-air temperature sensor. The processor may be programmed to determine a working-fluid-charge condition of the heat-pump system based on the first and second air temperatures.