Hi, We have two tank gas water heater each with expansion tanks. Recently we noticed that the T/P was leaking on our porch. Thinking I had isolated it to one tank, I replaced the valve with one from Lowe's. I then noticed that the other one was still leaking, so I replaced the other. Still leaked. Did some research and found that whole house water pressure could be the cause and remembered hearing that my neighborhood had very high pressure though I do have a PRV. Had the utility come out and they measured 150 at the meater and 80 at the house with low volume. They concluded the PRV was bad or needed adjustment. Had a plumber out today and they tested house pressure at an outdoor spigot and it was at 150. So they dug up and replaced the PRV and left saying the house was at 75. I also had them check the pressure in the hot water heater expansion tanks and they said they did and added some air. As they left we noticed the T/P still leaking. He exercised the valves and it was still leaking. He took apart the T/P outlet pipe at the tanks and we saw no dripping at the valve. He then blew the residual water out of the pipe by mouth. They left hoping that all was good. Well, they have been gone for a couple of hours and the hot water T/P is still leaking. I don't know what else this could be! Any thoughts are appreciated.