Systems and methods are directed to water healer systems, including combi boilers and instantaneous water heaters, for initiating pre-heat and energy savings operations. Embodiments of the present invention can include at least one heat exchanger, a plurality of temperature sensors sensing water temperature at one or more locations within the water heater system, and a control system in communication with the first and second heat exchangers. In embodiments, the control system can be configured to at least: determine an expected demand for hot water, determine a target modulation rate based on the plurality of temperature sensors, and the expected demand, monitor the plurality of temperature sensors and a flow rate, and update the modulation rate based on at least one of a detected change in flow rate and a detected change in at least one of the plurality of temperature sensors.

A hybrid heat system, a capacity allocation control method thereof, a readable storage medium and a control system. The hybrid heat system includes a plurality of modular heat recovery units with an air-conditioning mode and a water-heating mode, and a plurality of modular air-conditioning units with an air-conditioning mode, the capacity allocation control method including: a classification step S100 for classifying the compressors in the plurality of modular heat recovery units and the plurality of modular air-conditioning units according to unit category, unit state and start-stop state; a sorting step S200 for sorting classified compressors according to operating time; and a search step S300 for searching target compressors from sorted compressors based on preset energy efficiency search criteria.

A water heater system including a boiler having a heat exchanger and an indirect water heater having a heat exchanger, and a controller configured to activate a pump such that the water flows between the boiler heat exchanger and the indirect water heater heat exchanger, and to control a heat source to provide heat to the boiler at a firing rate. The water heater system measuring temperatures of the water at the boiler water inlet and at the boiler water outlet, calculating an amount of heat transfer from the boiler heat exchanger to the indirect water heater exchanger based on the measured temperatures, and adjusting the firing rate based on the calculated amount of heat transfer to determine a heat transfer capacity of the indirect water heater exchanger.

A heat pump assembly (100) arranged to be connected to a thermal energy circuit (300) comprising a hot conduit (302) configured to allow thermal fluid of a first temperature to flow therethrough, and a cold conduit (304) configured to allow thermal fluid of a second temperature to flow therethrough, the second temperature is lower than the first temperature, and a cooling machine assembly (200) arranged to be connected to a thermal energy circuit (300) comprising a hot conduit (302) configured to allow thermal fluid of a first temperature to flow therethrough, and a cold conduit (304) configured to allow thermal fluid of a second temperature to flow therethrough.