MY185357A - Delta-t expander for heat pump - Google Patents

Abstract

A heat-pump heating apparatus (1) is provided with a means to continuously mix hot fluid via a bypass port (31b) with cold water via an inlet (31a) of a 3-way valve (31) to raise the temperature of incoming water to a predetermined set point temperature before passing through condenser (12) so that the water gains a further small temperature increment to achieve the target hot water temperature. The 3-way valve (31) is driven by a motorised actuator (31c) operatively connected to a temperature controller (33) that receives signals from a temperature sensor (34) disposed at the inlet (22) of condenser (12) and continuously evaluates the temperature of water at said inlet (22) and its difference with a predetermined set point temperature, then, generates an appropriate output to said motorised actuator (31c) to continuously modulate the 3-way valve (31) thus, allowing a correct amount of hot water to mix with cold water to achieve said set point temperature. Said set point temperature is a little lower than the final hot water temperature exiting the heat exchanger (33) by a difference that is equal to the temperature rise achieved at the selected flow rate as water flows through the heat exchanger (33). (Figure 1)