My the check valve started to show signs of water the first day I used my new heater. So I turned down the thermostat. It still run water. So I turned it way down, and it still does it. When they installed the new heater, the plumber checked the inline pressure and said it was fine. So do I have a bad check valve on this heater? Is a thermal expansion tank necessary? How hard are they to install?
JaKe