Heat pump system and method for monitoring valve leaks in a heat pump system

A method for monitoring valve leaks in a heat pump system comprising a heat medium circuit in turn comprising

• at least three heat exchanging means arranged to transfer thermal energy between a heat medium and a respective heat source or sink selected from outdoor air, a water body, the ground, indoor air, pool water, tap water or a topmost ground layer,
• a valve means arranged to selectively direct the heat medium to at least two of said heat exchanging means, and
• a control means arranged to control said valve means,
• wherein the heat pump system comprises respective temperature sensors both upstream and downstream of at least one of said heat exchanging means,
• wherein the method comprises:
• a step in which the control means reads temperature measurement values comprising at least one value read from said sensors and, based upon these values, determines the at least two of said heat exchanging means to which the heat medium is selectively directed, and
• a step in which the control means reads, repeatedly over time, a measured temperature value upstream and downstream of one of the heat exchanging means to which the heat medium is not directed, and sets off an alert in case a difference between the read temperatures increases by more than a predetermined value between a reference reading, measured previously but after a disconnection of delivery of heat medium to the heat exchanger to which the heat medium is not directed, and a later reading, measured after the reference reading while the heat exchanger to which the heat medium is not directed still does not receive any heat medium.