Re: Water Pressure - Thermal Expansion??
Posted by Deb on April 01, 2004 at 10:32:13:
In response to Re: Water Pressure - Thermal Expansion??
: I recently had to replace my gas hot water heater. I raised the temperature of the new hot water heater to get more hot water fro a longer period of time. Water then began coming from the pressure relief valve into a pan on the floor. I never had any problems with my old water heater.
: I had the man who installed the water heater check it. He claims that I have 90 pounds of water pressure coming into the house. I have had no clanging pipes, leaking faucets, or running toilets which I have been told are symptoms of too high water pressure. He said because the hot water heater is a closed loop system, I now need a thermal expansion tank and the new water pressure adapter. It seems strange that I can replace a 20 year old unit and end up with a system that is worse and more costly than what I had before. What's the story here?

You do not have a "worse and more costly system". You have altered the conditions. You raised the water temp in the new heater and that raises the pressure. How high did you raise it? An expansion tank is a minor thing.
The temperature pressure relief valve line should be run to the outside. If it opens completely, the drain pan will never take the flow and you will have a flood.
90psi is barely over the 80psi that requires a pressure reducer, so you may well have never had any obvious problems. I have seen people with pressures as high as 120 go a long time before they start having problems.
The Pipewench

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