Help!High static pressure and knocking noise when a faucet or shower is running

[Joe V]

The tenant at our previous home called me that they have observed water pressure issues past 2-3 weeks. When a faucet is open when someone is showering, the pressure reduces too low in the shower until other faucet is shut. Couple of days back, they reported that they are hearing knocking/thumping noise in a wall behind master bath shower even when it is not open.

I suspected PRV issues. This home was built in 2001. I connected water pressure meter to outside faucet. It showed 100-110 psi. Then I located PRV and turned the screw on top counter clockwise to reduce pressure. That didn't make any difference. The pressure stayed at 100+ psi. Then I turned water off completely at city main meter inlet. Opened all faucets and let them drain so that air goes in. Then opened city water inlet and the closed all the faucets. Waited for pressure to stabilize. The water meter still is reading 110+ psi.

Attached is picture of PRV buried in ground. I don't know if it is Watts/Wilkins/Whatelse brand of PRV that I have.

I am wondering if I need to anything else to diagnose the problem. Is it classic failed PRV or something else?
If you think it is PRV gone bad, do I need to replace the whole thing or are there spare parts to rebuild the PRV?
How do I know what brand/model of PRV do I have?

I appreciate your help.

Thanks
Joe

 

[Reach4]

Sometimes outside faucets don't get fed via the PRV. Yours is probably fed via the PRV, but you can take pressure from a laundry tap or the drain valve of the water heater.

If you straighten out that metal tag, and gently wash the dirt off of the tag, there is a good chance you can read the make and model from the tag.

 

[Sponsor]

 

[Joe V]

I am heading that way later in the day. Thats a great idea to wash the label and get the model info.

If I end up replacing the PRV, what are the recommendations for buried in ground type PRV like I have.
I saw videos on Youtube with PRV that has heat expansion propagate back to city water lines, PRV with pressure gauge etc.

 

[Joe V]

I got a picture of the name tag. It is Watts PRV. Looks like 3/4". The model is not clear from the picture.

 

[Jadnashua]

With a PRV, you should always include an expansion tank in the home.

Many utility companies are following national guidelines and adding check valves to protect their supplies, so a bypass in a PRV is a total waste of money as there'd be no place for the water to go.

PRVs don't last forever. Some have rebuild kits, but if you're paying for the labor to take it out and rebuild then put it back, a new one may be cheaper.

 

[Joe V]

I scheduled a plumber to come take a look at it. The area where the PRV is accessible, but there will be digging involved to replace it.
Wondering what I am expected to pay for labor and parts. The home is in Austin, TX.

I just got response from Watts support team. They are awesome. The PRV that I have is LFN55B-DU (https://www.watts.com/products/plum...ressure-reducing-valves/lfn55b/lfn55b-du-2-in).

 

[Joe V]

I had it replaced with new one with help of a plumber. They charged me $600.

Later while I was looking at old and new PRVs, it looked like the top nut can be unscrewed and the guts replaced with new one. That is an option Watts guy suggested too.

My current home has aging PRV too. If I were to repair it, that is what I like to do. But my question is the tool I need to be able to place from top and screwn or unscrew it with a T like handle.

This is how the PRV looks from top.

 

[Reach4]

I had it replaced with new one with help of a plumber. They charged me $600.

Later while I was looking at old and new PRVs, it looked like the top nut can be unscrewed and the guts replaced with new one. That is an option Watts guy suggested too.

In LFN55B-DU, the DU stands for dual union.

What is at the "current home"?

What was your PRV replaced with? Same model number?

 

[Joe V]

I quoted wrong model number. The one that was there is 3/4" PRV. It is replaced with LFN45B-M1 which 3/4" PRV.
I have same one at current home.