High Water Pressure-Replacing PRV and Expansion Tank

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DMMU

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We had a plumber come out for what we thought was a leak and it turns out our water pressure is too high. We looked in the crawl space and located the pressure regulating valve and expansion tank for the water heater. Apparently the expansion tank isn't working as he took off the cap and nothing came out when he pressed into the nozzle with a phillips head. In the end they recommended replacing both PRV and expansion tank since apparently they work in tandem, as well as installing the expansion tank directly above the water heater instead of in the crawl space. Additionally he recommended installing a check valve.

So now I'm putting my new membership to the forum to use! It would be great to hear from any pros or anyone with experience if their recommendations are what I should go with. I understand the high water pressure definitely needs to be addressed, just want to zero in on what the right fix would be in this situation. Thanks!
 

JoeD

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Everything but the check valve sounds correct to me. Not sure of the reason for the check valve.
 

DMMU

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Everything but the check valve sounds correct to me. Not sure of the reason for the check valve.

Thanks for confirming! He said the check valve cuts off water flow in case of an issue. Something about it not causing further damage, but the precise example is escaping me right now.
 

JoeD

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That would not be a check valve as I understand it. That would be a shut off valve connected to some sort of water sensor.
 

DMMU

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I see. Is that something commonly installed with a water heater?
 

ajaynejr

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Press the nozzle (Schrader valve; tire valve) on the expansion tank and nothing comes out:

Expansion tank has lost its air cushion and that can result in abnormally high pressure in the water system.

To fix that:

Turn off the main water valve.

Open a hot faucet on a higher floor.

Get a bike pump or tire pump and add air to the "nozzle" until you get the pressure (tire gauge needed) to about 40 psi.

Close the upstairs faucet.

Turn the water back on.

Hint: There should not be a check valve or any valve in the pipe path between the expansion tank and the water heater. It is suggested that the expansion tank be on the cold side of the system, otherwise as you use hot water some of the (cooled off) water in the expansion tank will come out somewhat randomly as you use water and your shower will give irregular temperature.
 

kok328

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Press the nozzle (Schrader valve; tire valve) on the expansion tank and nothing comes out:

Expansion tank has lost its air cushion and that can result in abnormally high pressure in the water system.

To fix that:

Turn off the main water valve.

Open a hot faucet on a higher floor.

Get a bike pump or tire pump and add air to the "nozzle" until you get the pressure (tire gauge needed) to about 40 psi.

Close the upstairs faucet.

Turn the water back on.

Hint: There should not be a check valve or any valve in the pipe path between the expansion tank and the water heater. It is suggested that the expansion tank be on the cold side of the system, otherwise as you use hot water some of the (cooled off) water in the expansion tank will come out somewhat randomly as you use water and your shower will give irregular temperature.

I guess the fact that nothing came out, not even water, indicates the diaphragm might still be good and not waterlogged. And something about trapping water in an expansion tank with a check valve just doesn't sound right. Pump up the tank and see what happens and how long it holds pressure and put it on the preventive maintenance list to check pressure.
 

DMMU

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I had another plumber come out, the recommended fixes were done as the expansion tank was shot, water pressure is not at 70-75 psi and I plan on checking it once every month or 2 from now on.
 
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