It is most likely the PRV responsible for the spiking.I'm confused. Based on feedback from others, the problem with the spiking is due to not having an expansion tank, not the PRV. Or is that incorrect?They are pretty cheap to replace and our plumber said they have a limited lifespan. You definitely don't want pressure at 90 or 100, even if they are spikes. I'd just get it changed and make sure they put in a good quality PRV. Or get a second opinion from another plumber.
But, depending on how your hot water plumbing is configured, it could also be affected by the lack of an expansion tank. For example, my plumbing has a check valve on the cold water line going into the hot water tank. That means that the expanding hot water cannot push back into the cold water side and would not cause your pressure gauge to see any higher pressures due to the hot water expansion. Now, I don't know if you have a check valve or not, it isn't required. If not, the hot water expansion can go back to the cold water side and that would cause your pressure gauge to see any higher pressures due to the hot water expansion. As an example, my expansion tank internal membrane was ruptured (i.e. not working) and the hot water expansion caused the hot water tank pressure relief valve to open slightly causing water to dribble out when the hot water was heating up. This pressure never got back to the cold water inlet because of the check valve that is installed.
You can test this by turning off the hot water for a day and monitoring the pressure with that gauge you have been using. Since the hot water heater is off, there will be no hot water expanding. If the pressure still goes up, it is for sure the PRV. If not, then could be the lack of an expansion tank.
Statistics: Posted by twh — Tue Jun 25, 2024 12:22 am — Replies 40 — Views 3628