Hi,
I tried to use pin P1,P2 for running water pump, but in the situation, when set temperature=actual temperature Mr. Silence is in “standby mode”, but switch P1,P2 is still ON and pump is still running 
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So, if you have integrated Mr. Silence in HA, do you have some automation to run Mr. Silence & water pump? Stop pump when temperature is ok and run again when HVAC want to heat again…