Water Pressure Reducing Regulators

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jim dandy

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2 years ago I installed two Watts # LF25AUB-Z3 3/4 inch water pressure reducing regulators on two different jobs. Recently I noticed that they both have problems.

The water main inlet pressure is 61 lbs psi and spikes to around 70 psi. The regulator is set to 55 lbs psi.

From the begining the water volume died down after about 10 seconds of water using (open hose bib), like the valve wasn't allowing the full volume of water to pass through the valve? The other day I noticed that the pressure had gone up on the outlet side to main line pressure and the regulator was no longer adjustable. I see this regulator is has been discontinued.

4 questions:

1) Was this LF25AUB-Z3 3/4 inch reducing regulator valve the wrong one to install in the first place?

2) What has caused this regulator valve to become no longer adjustable?

3) If I had increased the LF25AUB-Z3 reducing regulator valve to 1 inch would that have given me more voulme of water through the valve?

4) I am looking at another valve Watts #LFU5B-Z3. Is this a better valve than the LF25AUB-Z3 and if so should I go 3/4 or 1 inch

Thanks..........Mark
 

Jadnashua

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Did you install expansion tanks with those PRVs? Without an expansion tank, the internal pressure will rise after using some hot water. If the water pressure rises that 15psi, that implies you either have a bad ET, or don't have one at all.

Some PRV's have a built-in by-pass, and that would prevent the house pressure from rising much above the supply (it can't press back until the pressure in the house exceeds the supply to open the bypass against that incoming pressure). If yours have that feature, it's broken.

Code requires a PRV when the supply exceeds 80psi...sounds like you may not actually need one (some codes might call for it, though), but it certainly doesn't hurt.
 

Reach4

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The water main inlet pressure is 61 lbs psi and spikes to around 70 psi. The regulator is set to 55 lbs psi.
If the pressure stays under 80, no regulator is required.
 

Jim Mills

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Biggest complaint I see, besides squeeking from those "cheaper" valves, is reduced flow. The u5b is a great valve, and has a much higher flow rate. It's my go to valve for most residential installs.
 

jim dandy

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Biggest complaint I see, besides squeeking from those "cheaper" valves, is reduced flow. The u5b is a great valve, and has a much higher flow rate. It's my go to valve for most residential installs.

Thank you all for your comments and suggestions.

Both jobs that use the LF25AUB-Z3 3/4 inch PRV failed and have ET's. The original PRV when new had a reduced water flow right from the beginning. The LF25AUB-Z3 PRV does have a bypass built in.

These two houses are on a slab with PVC piping under it so the owners have concerns about the pipes coming apart, thus the PRV's. If I change the PRV to the U5B PRV should I use a 3/4 inch or 1 inch inlet?

Will the flow be better with the 1 inch PRV or the same?

Thank you......Mark
 
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hj

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A 1" valve will have more flow than a 3/4" one. I hope you mean the house has CPVC under it and not PVC. (And if the there are connections under the floor, which either one would require), then NEITHER one should have been used. When the pressure increases will tell you whether it is the valve or the ET. If it drops when a faucet is opened and then immediately starts to rise again, it is a bad PRV. If it only rises after hot water has been used then it is a bad expansion tank. If the valve cannot be adjusted, then the diaphragm has failed, although that would usually be indicated by water leaking from the top of the PRV.
 

jim dandy

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A 1" valve will have more flow than a 3/4" one. I hope you mean the house has CPVC under it and not PVC. (And if the there are connections under the floor, which either one would require), then NEITHER one should have been used. When the pressure increases will tell you whether it is the valve or the ET. If it drops when a faucet is opened and then immediately starts to rise again, it is a bad PRV. If it only rises after hot water has been used then it is a bad expansion tank. If the valve cannot be adjusted, then the diaphragm has failed, although that would usually be indicated by water leaking from the top of the PRV.

Thank you for the quick reply.

I am not sure what type PVC was used under the slab or if it has any connections to it. I do know that schedule 20 PVC was used off the water meter up to the house (which I do not like). This house is located in Cascades World Golf Village Saint Augustine Florida. Inside the house is all CPVC.

Yes what you say is what was happening here, but no water leak at valve. Pressure would build up and as soon as the water bib was opened the flow volume dropped off. This was on a 1 1/2 year old LF25AUB-Z3 PRV 3/4 inch. If the water main is 3/4 inch PVC would I get a better water flow if I used a 1 inch PRV. I know you said yes but I may have a 3/4 inch water main (don't remember). I could adapt it up to use a 1 inch Valve if you think I still would get better water flow through the valve.
 
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