PRV and Thermal Expansion tank?

I recently purchased a house and the inspectors said I needed to install a Pressure Reducing Valve as the pressure measure at the spigot outside was 80 psi. I've measured it at 78-80 pretty consistently since we moved in.

So, I have a few questions:
-Is 80 psi high enough to necessitate installing a PRV?
-If I install a PRV, do I then need to install a thermal expansion tank on my water heater or are the two not always necessary together?

Thanks a lot for the help!

I hear 55-60 psi is optimum. I've always had a good PRV installed but never needed an expansion tank.

Havasu has become very astute in his recommendations

Thanks. I'm learning, albeit very slowly.

A PRV should be installed at that pressure. Not more than 60psi is required. An expansion tank is a good thing to have to prevent the relief valve from blowing off your hot water heater. I've seen it happen where city workers shut a valve for a line they are working on, and the vibrations travel up the line and pop the relief valve....then floods happen. Where I'm at they also want you to install a double check valve, so your house cannot get siphoned a main water line burst in the street.

azita said:

I recently purchased a house and the inspectors said I needed to install a Pressure Reducing Valve as the pressure measure at the spigot outside was 80 psi. I've measured it at 78-80 pretty consistently since we moved in.

So, I have a few questions:

-Is 80 psi high enough to necessitate installing a PRV?

-If I install a PRV, do I then need to install a thermal expansion tank on my water heater or are the two not always necessary together?

Thanks a lot for the help!

Click to expand...

As mentioned, 60PSI @ the most.

You need to leave the pressure gauge connected for at least 24hrs. to see if any event (heating) leads to short time higher pressure (tattle-tale hand). The expansion tank design is to absorb the pressure surges to prevent possible damage(s) in the system.

I believe current code calls for the tank.

Matt30 said:

A PRV should be installed at that pressure. Not more than 60psi is required.

An expansion tank is a good thing to have to prevent the relief valve from blowing off your hot water heater. I've seen it happen where city workers shut a valve for a line they are working on, and the vibrations travel up the line and pop the relief valve....then floods happen.

Where I'm at they also want you to install a double check valve, so your house cannot get siphoned a main water line burst in the street.

Click to expand...

Won't the PRV stop any vibrations as you described?

Why the double check valve? Are they concerned the one way valve may stick or leak during certain events?

On a learning curve in W (By GOD) V...

A double check works better under higher pressures. Instead of a single check taking the brunt of the action, the double check distributes the force evenly between the two, and is essencially more reliable.

Matt30 said:

A double check works better under higher pressures.

Instead of a single check taking the brunt of the action, the double check distributes the force evenly between the two, and is essencially more reliable.

Click to expand...

THANX!

Makes sense...