Failed PRV

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Nezil

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I recently installed a softener at our home, and as part of this process decided to measure my water pressure.

To cut a long story short, our 10 year old 1-1/4" Watts 25AUB-Z3 appears to have failed. The failure mode is that it is reducing pressure when water flows through it, but as soon as flow stops, it doesn't seal, resulting in a rise to street pressure of 95 PSI over about a 30 second duration.

The photo below shows the location of the unit (central leg), which is actually under a shrub, and therefore a real pain to get to.

IMG_20140710_134526.jpg

It's not actually buried, but it nearly is, and I have no idea why there is tape wrapped around the union side of the pipe.

Looking online, I can find a replacement PRV at a cost of around $210, or a repair kit for $65. This is quite an unexpected cost, and I'd rather not have to cough up in excess of $200 if I don't have to.

I realise that re-building a PRV is probably not easy, but since adding the softener, I've got pretty good at cleaning our particularly type of scale that we suffer with - Muriatic acid! It's strong stuff obviously, but an hour soak in a 1:4 solution dissolves the scale to the point where it pretty much wipes off. I wouldn't want to put every material in such a solution, but I'd have thought the ones used in a PRV would have no issues.

My question then is... Should I go through the trouble of repairing the PRV, or just replace it with a new one?

Does anyone know what the tape wrap is by the way?

Any help or advice appreciated!
 

Terry

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The tape is UPC tape. A plastic tape to prevent contact of copper with cement.

You can just rebuild the PRV if you have a kit for it. That may be easiest. It's the diaphragm that goes bad.
 

Nezil

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Thanks for the response Terry, the tape makes a little more sense now.

I was thinking about rebuilding the PRV in situ, but that's probably not a good idea because it will be difficult to get to the back of it for access to the two caps located there.

As I understand it, the top (input side) of the PRV is a union connection, so that should be straightforward to remove, but the bottom is just FPT, so the PRV will have to be unscrewed in order to get it off. Looking at the PVC branch, which is for irrigation, to the right, I don't think there is enough space to turn the PRV!
 

Dj2

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By installing a brand new unit, you will be able to raise it up a little, so it's not buried under the mulch/shrub.
 

Reach4

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The old PRV might do OK in the interim if Nezil opens a tap to just a drip.
 

DonL

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Repairing it in place should be no problem.

Do you have a expansion tank ? Maybe I missed it.


Good Luck on your project.
 

hj

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The confusing thing about your photo is that the pipe to the left appears to be the "larger one" with a "main shut off valve" and reducing tee that then goes to the PRV. This raises the question as to WHAT the PRV is reducing the pressure to?
 

Nezil

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@hj, the line to the left is the main water line that comes from the meter. That line is not reduced at all, it's 1-1/4", though I agree that the photo does look deceptive.

The first branch (also 1-1/4"), with the failed PRV in series, goes to the home. It's actually branched again into a 1" line that feeds the fire sprinkler system, and a 1-1/4" line that feeds the rest of the property.

The second branch is for the irrigation system. I should check the PRV on that branch as well I guess, but I've not done so yet. Thankfully, that is a smaller Wilkinson PRV, so if it does need to be replaced, it's much cheaper to do so!
 

Gary Swart

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I hope that the "smaller Wilkinson" is not a PRV but a backflow device which you should have in the irrigation line.
 

Nezil

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@DonL, I don't have an expansion tank, no. None of the properties in my development do, which I have to admit is strange.

When I spoke with the local plumbing supplier here about it, they said that theoretically I should have an expansion tank, but many properties do not. If all 8 in our development don't, why not put a lazy needle pressure gauge on for a few days and see how high the pressure gets. If it stays within the 80 PSI recommendation, you'll not be risking any damage.

He was quick to re-iterate that an expansion tank is the correct thing to do, but that we could probably get away without one - if it ain't broke, don't fix it (not sure if that is a British phrase, but you get the point).
 

DonL

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@DonL, I don't have an expansion tank, no. None of the properties in my development do, which I have to admit is strange.

When I spoke with the local plumbing supplier here about it, they said that theoretically I should have an expansion tank, but many properties do not. If all 8 in our development don't, why not put a lazy needle pressure gauge on for a few days and see how high the pressure gets. If it stays within the 80 PSI recommendation, you'll not be risking any damage.

He was quick to re-iterate that an expansion tank is the correct thing to do, but that we could probably get away without one - if it ain't broke, don't fix it (not sure if that is a British phrase, but you get the point).


Well it is broke.

And it should have a tank.

Even with a new PRV the pressure is going to rise.
 

Nezil

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OK, so turning my attention to the tank while I wait for the PRV and Repair Kit to arrive...

There is plenty of space above and around my water heater, but there isn't much space for additional piping where the cold water feed comes out of the wall - A photo illustrates this best (I'll take one and edit this post).

I'd rather not de-solder the joints around the Ball Valve, and I'm therefore thinking of other possible options.

Would it acceptable to use a 3/4" Lead Free Brass FIT Tee, and then put this Tee at the input to the water heater. I should then be able to run a 1/2" pipe over to the wall from there, followed by a 90 degree elbow, 3/4" FIT fitting and screw in the tank, clamped to the wall.

Does there seem anything wrong with this approach? I know that solder Tees are the usual approach, but I'd rather not do that if I don't need to.
 

DonL

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It does not need to be at the water heater. Just on the supply line. Near the Softener maybe ?

Your Idea sounds good. But you may be making it harder than needed.


Good Luck.
 
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Jadnashua

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Technically, the ET should be connected between the tank and any cold-water shutoff to the tank so that it is always able to handle any expansion. How you tap into that cold water supply really doesn't matter. You should also make sure you support the tank properly, since when it fails (they all do eventually), and fills up with water, that extra weight does not put undue stress on the lines or fittings.

Unless you have a very small water heater, OR a leaking valve somewhere, you'll almost always end up discharging some water from the WH's T&P valve after a big hot water usage when you have a closed system (the PRV makes it a closed system). That T&P valve doesn't like to be opened regularly, and the mineral deposits from frequent discharges can cause it to seize up and never close or never open if it needed to for safety.
 
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