Home>Discussions>PLUMBING>How to determine if a Water Pressure Reducing Valve (PRV) is working properly
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srobb
How to determine if a Water Pressure Reducing Valve (PRV) is working properly
srobb

I've been trying to track down water pressure/flow issues throughout the plumbing in my entire house, but haven't found anything which made any significant difference. For example, I discovered that the main valve and a few others were not fully open. I am able to access all other valves and they are fully open. All lines are copper. My house is a single level with a basement (where the main is located). My neighbors do not have any problems.

Here's my configuration:

City Water -> 3/4" lines -> main -> gauge (reading is maxed out over 100 psi) -> PRV -> gauge reading static 60 psi -> valve -> continue 3/4" lines feeding 1/2" lines for all fixtures.

I have a thermal expansion tank with the hot water heater which is also set to 60 psi.

As soon as any water fixture is turned on (sink, shower, toilet flush, washing machine, etc.), the pressure on gauge immediately following my PRV drops significantly (falls to 20psi or less). As a result, trying to use a second fixture is difficult and a third is near impossible. Additionally, I attempted to turn all water fixtures through the house on. During this test, the water fixtures on the main level did not put out any water.

I'm inclined to believe there is an issue with the PRV. Is that the right place to be looking? Should a PRV have such a large drop in pressure when one fixture is open?

ed21
Re: How to determine if a Water Pressure Reducing Valve (PRV) is working properly
ed21

I would suspect the PRV too. Is it sized properly or adjusted properly. Maybe just old and worn out. I'm not too familiar with them. I don't know if their is any maintenance or repair that can be done to them. At least they aren't too expensive.

dj1
Re: How to determine if a Water Pressure Reducing Valve (PRV) is working properly
dj1

try setting your PRV up to 70 - 75, and see if the situation improves. If you don't know how, just tell us.

How old is the PRV?
Do you have a whole house water filter?
Has work been done, where dirt could enter the main line? (street work, etc). Sometimes sand, tiny rocks get in and clog the valve.

srobb
Re: How to determine if a Water Pressure Reducing Valve (PRV) is working properly
srobb

dj1- I do not have a whole house water filter. The PRV was installed prior to our moving in, but I'm guessing it's not any older than 10 years old.

With respect to work recently, I can't recall anything in particular. However, along those lines, I just noticed something interesting. I took the heads of all the faucets that were easily accessible. They were all filled pretty good with white-ish debris. I cleared it out and let them run. It did not fix the problem, but the sinks are running better. I let them run and flipped the shutoff valves off and on and went back and checked and there is more of the white-ish debris. I wonder if the issue is related to the lines being clogged?

dj1
Re: How to determine if a Water Pressure Reducing Valve (PRV) is working properly
dj1

With the new info...

I'd replace the PRV. If you know how, just get a new one, same size and model (so you won't need to modify the pipes). You can take the one you have apart and service it, but since a new one is around $50, don't waste your time.

New valves come pre-set at 55-80 (it should say on the package).

See if that improves the situation.

srobb
Re: How to determine if a Water Pressure Reducing Valve (PRV) is working properly
srobb

I'm curious about the rationale? Do you suspect that the PRV might be partially obstructed?

Jack
Re: How to determine if a Water Pressure Reducing Valve (PRV) is working properly
Jack

If the pressure after the PRV drops to 20lbs when you open a faucet does it immediately go back to 60 when the faucet is shut off or does it build up slowly?

Jack

dj1
Re: How to determine if a Water Pressure Reducing Valve (PRV) is working properly
dj1
srobb wrote:

I'm curious about the rationale? Do you suspect that the PRV might be partially obstructed?

Could be. You could also have a torn or worn out diaphragm - but these things are unknown at this moment. After you change the valve you will be able to look into it.

I have never had time for "investigations", always been under pressure to fix things quickly. That's why I recommend replacement in most cases - not to have service interruptions.

Nowadays things a more relaxed though :D:D

Still, I wouldn't spend a minute on a 10 year old PRV, when a new one is $50.

dj1
Re: How to determine if a Water Pressure Reducing Valve (PRV) is working properly
dj1

srobb,

I read your original posting again, and I have a couple of questions:

- How many end users do you have? (faucets, toilets washers, etc.)

- What size is your main, from the street to the house - you mentioned 3/4, is it 3/4 all the way? You can look at the meter, and tell what size pipe is coming off the meter.

srobb
Re: How to determine if a Water Pressure Reducing Valve (PRV) is working properly
srobb

Thanks for the explanation, dj1. That definitely helps.

I don't know that it immediately goes back to 60psi, but I don't think that it take a noticeably long time, either. Maybe 30 seconds tops.

I took another look by the PRV and the main and noticed another component I never took note of before. I actually have no idea what it is. It's between the main shutoff and the first gauge and PRV. It looks to have a light electrical wire running to it. I'll try to see if I can figure out what it is to determine if it has any role in the problems.

ed21
Re: How to determine if a Water Pressure Reducing Valve (PRV) is working properly
ed21

Probably just a ground wire

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