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Rick, Construction Supervisor
Category: Plumbing
Satisfied Customers: 21370
Experience:  Licensed Master plumber with 40+ yrs. experience.
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We recently had a water pressure pump installed to help with

Customer Question

We recently had a water pressure pump installed to help with home water pressure and outdoor sprinkler system. The pump was installed with a check valve before the pump coming from the main water supply.
Since the installation, the pressure relief valve on our hot water heater is leaking.
I just replaced it thinking it was bad, but the new one is also leaking. Coming from the long tube down the side of the water heater (40 gallon).
The water heater is over 12 years old.
Anyone have any ideas on the cause?
Submitted: 1 year ago.
Category: Plumbing
Expert:  Rick replied 1 year ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.

What you're describing is the result of your recent work. The water in the water heater expands as it heats up. Before it would expand back into the water main. Can't do that now with a check valve and your starting (tank full of cold water) pressure is higher now too because of the booster pump. The fix is to install a thermal expansion tank (see attached pic) on the cold water line near the heater. It must be rated for a water heater not a hot water heating system.