Return temperature

Return temperature is the temperature of the heating water returning from a heating circuit to a heat pump, boiler or heat network after it has passed through radiators, underfloor heating or other heat emitters. It is read alongside flow temperature because the difference between the two shows how much heat the circuit has taken from the water and affects flow rate, emitter output and sometimes heat-source efficiency. In heat pump documents it may appear in design water temperatures, commissioning checks, controller data or hybrid-system limits. It is not the room temperature, the thermostat setting, the Delta T value itself or proof that the heating system is efficient or correctly balanced.