A heat pump system in which the amount of opening of an expansion valve is set to an optimum value in dependence upon the inlet temperature of water undergoing heat exchange at a utilization side heat exchanger and an inlet temperature of air undergoing heat exchange at a non-utilization side heat exchanger....http://www.google.fr/patents/US4498310?utm_source=gb-gplus-shareBrevet US4498310 - Heat pump system
