High pressure
 

The house is on city water which normal pressure 50 psi. This is a new hook up, one year ago. When home is left for the weekend there is high pressure built up 125 psi. Once a valve is turn on all back to normal pressure. Some one told us there could have been a check valve put on by the city or on the city meter and the hot water tank now builds high pressure. Is this true? What's the correct fix? bjr23

There could be a check valve somewhere, or PRV valve thats not working correctly. If so find it replace it.