PRV vibration

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kami25

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I don’t know the pressure from the street. The old prv leak was a hairline crack in the casing. Supposedly this new model has a feature to compensate for expansion according to the spec sheet. I will see if I can fix up a bypass. Thanks
Bypass Feature
This regulator has a built-in thermal expansion bypass feature. This feature prevents downstream pressure from rising to more than 10 psi (69 kPa) above the supply pressure.
NOTICE
The Bypass feature will not prevent the pressure relief valve from opening on the hot
 

kami25

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I don’t know the pressure from the street. The old prv leak was a hairline crack in the casing. Supposedly this new model has a feature to compensate for expansion according to the spec sheet. I will see if I can fix up a bypass. Thanks
Bypass Feature
This regulator has a built-in thermal expansion bypass feature. This feature prevents downstream pressure from rising to more than 10 psi (69 kPa) above the supply pressure.
NOTICE
The Bypass feature will not prevent the pressure relief valve from opening on the hot
 

Mliu

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The Bypass feature will not prevent the pressure relief valve from opening on the hot
The hairline crack in the old one was from thermal expansion. You're lucky it was only that, not a pipe inside a wall bursting. I haven't seen a water heater explode, but I have seen a water heater tank split open.

Yes, I'm familiar with the bypass in the Watts regulators. I consider it a nice emergency backup, not a primary line of defense. Install an expansion tank. They're not expensive at all, especially considering the potential consequences of not having one.

The PRV bypass is simple: Two tees (one before and one after the PRV), two 90° elbows, one ball valve, and four short lengths of copper pipe to join everything together.
 

kami25

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Discovered something this morning. The tub/shower will only make the noise when using the shower. In the other bathroom in the shower the noise will only happen when the stream feature is used. The waterfall, or more water feature, no sound. Something backing up the water causing the noise? Hose bibs make the sound.
 

Mliu

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It appears to be caused when the total water flow is low. At higher flow, the vibration stops.

I suspect the problem may be that the pressure from the street is approximately the same, or perhaps lower, than the pressure setting of your PRV. You need to buy a water pressure gauge (they are inexpensive) and measure your water pressure with and without the PRV.

I recommend you get this one by Watts because it has an extra needle that records the high pressure.


You can buy it for $10 from Amazon
or elsewhere.
 

kami25

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I can hear the noise when the water is running in the meter box. Not as loud but it’s there.
 

Mliu

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I can hear the noise when the water is running in the meter box. Not as loud but it’s there.
That doesn't really tell you anything. Water is essentially incompressible. So sound (compression waves) travels very far in water. The vibrations are likely being produced by the new PRV and some of that sound is being transmitted through the supply pipe back to the meter.

If you want to solve your problem, guessing won't help. You need to diagnose as I discussed above. Start with knowing what your water pressure is from the municipal supply by using a pressure gauge.
 

Reach4

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The municipality may be able to tell you what your pressure at the meter is. I suspect they may have study data.
 

Mliu

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The municipality may be able to tell you what your pressure at the meter is. I suspect they may have study data.
They may. But it also may not be accurate as of today. Besides, the OP needs a gauge anyway to fully diagnose his problem and to set his PRV properly.

It's only $10, so I'm not sure why any homeowner would be averse to buying one.
 

Reach4

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They may. But it also may not be accurate as of today. Besides, the OP needs a gauge anyway to fully diagnose his problem and to set his PRV properly.

It's only $10, so I'm not sure why any homeowner would be averse to buying one.
Good points. However I did not see a place OP could currently hook to before the PRV. Maybe I missed it. Removing or disabling the PRV is a lot of work to get that number.

Finding that the city pressure was only 80, so no PRV needed, would be a happy, but unlikely, surprise. It has happened to some.

I agree that the new PRV is probably the problem. Contacting Watts would probably get him a replacement, but maybe selecting a different PRV might be a good idea too. Watts might even upgrade him.

Nobody suggests that OP should not add a thermal expansion tank. I just thought I would add that in again.
 
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Mliu

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Good points. However I did not see a place OP could currently hook to before the PRV. Maybe I missed it. Removing or disabling the PRV is a lot of work to get that number.

Finding that the city pressure was only 80, so no PRV needed, would be a happy, but unlikely, surprise. It has happened to some.
Even 80psi is high for residential. Pressure in the house should be in the 50-60 psi range.

I agree that it may not be simple to get the street pressure. Adding a bypass to the PRV is a good way to do that. If he knows how to solder, correctly, that job is fairly easy and inexpensive. If he has to hire a plumber, then it may be cost-prohibitive.

I agree that the new PRV is probably the problem. Contacting Watts would probably get him a replacement, but maybe selecting a different PRV might be a good idea too. Watts might even upgrade him.
He's already replaced the new PRV with another new PRV and the problem remains, so it's unlikely (although remotely possible) that the PRV is defective. The PRV he has appears to be appropriate for his application, so I don't think an "upgrade" is warranted, nor do I think a different PRV will be an improvement.

Again, I suspect the problem is that the street pressure is very close (or possibly lower) than the pressure setting on his PRV. But it's impossible to know without learning what those pressures actually are.
 

kami25

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Had a plumber I have been talking to on the phone come take a look. He tested the water pressure from the city and it was 105 . He said in his opinion that the Watts prv can’t handle the pressure differences between the city and the house. He says he won’t even use Watts anymore. He said it would be a fine if the incoming pressure was lower. He is going to put in a different brand of prv and an expansion tank next week. He is 99.99 percent sure this will solve my humming. Thoughts?
 

Mliu

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Does the vibration occur only after you have not used any water in a while?
 

Reach4

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I agree that it may not be simple to get the street pressure. Adding a bypass to the PRV is a good way to do that. If he knows how to solder, correctly, that job is fairly easy and inexpensive. If he has to hire a plumber, then it may be cost-prohibitive.
While soldering, would add a drain valve that can mount a pressure gauge in after the shutoff and before the PRV. Alternatively, add a tee with a 1/4 inch FIP adapter to mount a 200 psi pressure gauge. Maybe have another downstream of the PRV for handy PRV setting.

To read the street pressure without soldering, he could put a pressure gauge on a spigot downstream of the PRV. Dribble water from a faucet. Turn up the PRV until the gauge reads 85 to 90. At that point, he would know that a PRV is needed. Then back the PRV off to 60 or whatever. The spigot dribbling is needed to set the PRV.

You would agree that calling Watts with the known info is a good idea. If the call results in a new bigger PRV that will mount differently, then have that in hand before soldering.
 

Mliu

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The Watts PRV you have is rated up to 400 psi input pressure. Watts is a reputable brand with a long history so they know what they're doing. I'm not sure why this particular plumber feels negatively about them.

My recommendation is to install only the expansion tank first. I'll wager that doing so will solve your problem. If it doesn't, then consider replacing the PRV.
 

kami25

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Are you thinking the back pressure is causing the problem? With a expansion tank there would be no back pressure no humming correct? He doesn’t like Watts because he has has too many problems with them.
 

kami25

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If I turn off the WH and see if the sound goes away would that mean the prv is okay and I just need an expansion tank?
 

Mliu

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Yes, if you turn off the heat entirely (leave the water supply valve to the heater open). Since your problem is intermittent, you will have to leave the hot water off for a while to get a good test.

If the sound goes away while the water heater is off, it's a pretty good bet that the expansion tank alone will solve the problem for you.

Make sure your expansion tank is the correct size for your heater and check that it's precharged to the correct pressure (should be at about the same pressure as what the PRV is set to).
 

kami25

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Could I use up the hot water and then do the test instead of letting the water cool down?
 
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