Originally Posted by techpappy
You said you have an expansion tank on top of hot water heater..that doesn't make sense to me..I think you must be referring to EX TANK above Boiler for hot water heating system..right?
If that is the case then where is the relief valve located..I think you said ..on line next to washing machine..was it the hot water feed or cold water feed ...
more oictures showing location of valves, cushion tank and HW tank and piping would be helpful
Pictures will help a lot here.
FYI UPC requires expansion tank for hot water storage devices in closed systems IE : Check valve at city.
Your increase in pressure is coming either directly from your city connection (are you on city water?) meaning that your pressure regulator isn't working properly or needs adjusting OR from thermal expansion occurring after the water heater is used, and during heating of the water.
If you're saying that the pressure relief valve leaked right away after changing it, can you tell me this : What is the pressure rating on said relief valve?
Usually a pressure only relief valve is used on a pump system. I'm not sure why you would have one if you're on city water (not sure about that still)
Does your water heater have a temperature/pressure relief valve in the top and/or side of it? This should be sufficient unless you're leaving pieces of the puzzle out that we can't possibly know about.