Need Advice: Cavitation at shutoff valve after installation of pressure reduction valve

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mipowell

mipowell

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Location
Atlanta, GA
I recently installed a new pressure reduction valve because the pressure in my water pipes was exceeding 130PSI. After installing the pressure reduction valve, the pressure is now reading approximately 45PSI. However, the pipes near the shut off valve and pressure reduction valve now seem to be cavitating when someone runs the water in the house (toliet flushing, running water at a sink) I understand that the cavitation can be caused by water going from high pressure to lower pressure in the reduction valve. This cavitation never occured prior to the installation of the pressure reduction valve and I am wondering if this is the direct result of having a working pressure reduction valve. The cavitation can be quite violent and I am afraid that the pipes or valves may burst.

Please note: I do not have a pressure tank installed and I was wondering if this might eliminate the caviation if I installed one next to the hot water tank.

Any advice on the root cause and solution to the cavitation is greatly appreciated.

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I don't think you would describe it as typical hammering, but there is an extremely loud vibration coming from the shut off valve. The pipe itself is not moving, but the valve is producing an extremely loud noise. Sounds like a train is coming through my house.
 
No, I have not tried. I'd like to understand why this could work. Should I try to keep the drop in pressure to not be such a drastic one - because the drop in pressure causes the cavitation in a valve?
 
I'm guessing you have a gate valve. The valve in frodo's picture with the red handle.
Check to see if that's fully open. If so, and if you can manage it, try closing it slightly, while the noise is taking place, to see if it has any effect.

You say, "you do not have a pressure tank installed". I assume you are talking about an expansion tank on the cold water inlet to your water heater. I'm surprised you haven't had your Pressure/Temperature Relief valve, on your water heater, relieving pressure occasionally.
You should have one, and yes it MAY help the cavitation problem you are experiencing.

The big difference in pressure, from 130+ psi to 45 psi could lend to the cavitation. So like @Geofd recommended, reducing that difference may do it.
 
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Diehard said:
I'm guessing you have a gate valve. The valve in frodo's picture with the red handle.
Check to see if that's fully open. If so, and if you can manage it, try closing it slightly, while the noise is taking place, to see if it has any effect.

You say, "you do not have a pressure tank installed". I assume you are talking about an expansion tank on the cold water inlet to your water heater. I'm surprised you haven't had your Pressure/Temperature Relief valve, on your water heater, relieving pressure occasionally.
You should have one, and yes it MAY help the cavitation problem you are experiencing.

The big difference in pressure, from 130 psi to 45 psi could lend to the cavitation. So like @Geofd recommended, reducing that difference may do it.
Click to expand...
I have a ball valve as my shut off valve. (the one with the silver, metallic handle) Regarding the tank, you are correct - I'm referring to an expansion tank. These tanks were not required when my home was built,(30 years ago) but I got a notice from my local water authority last year that said I should install one due to changes they were making in my neighborhood. I'm not certain what kind of changes would require the use of the expansion tank, but their letter said that their changes could reduce the life of my water heater if I did not install one.
 
The reason for the expansion tank is typically required/recommended when you have any type of device on your water supply that would prevent an increase in the house pressure/volume to find it's way back into the municipal water supply.
For example, PRV, check valve, or any other type of backflow device.
When your water heats up it expands and typically needs somewhere to expand to. Doesn't always cause a problem but could and has.
I'm curious as to what changes they would be making that would change anything for you, since you already had a PRV, which typically would require an expansion tank.
 
frodo said:
that is a globe valve not a gate valve

do you know how to tell the difference ?
Click to expand...

I would guess, the arrow.
Since a globe valves interior design always has the stem closing down on the horizontal seat before the water enters the stem area. :)

Not that I've seen very many water services but I've never seen a globe valve on a water service. I assume it was due to the inherent pressure loss thru them.

EDIT: Actually a better answer would have been , if it wasn't installed, by looking inside the valve.
 
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Here's a question for you!
When doesn't an arrow on a valve not necessarily indicate the direction of flow?
Here's a hint... It's a type of gate valve.
 
Diehard said:
Here's a question for you!
When doesn't an arrow on a valve not necessarily indicate the direction of flow?
Here's a hint... It's a type of gate valve.
Click to expand...

A globe valve is a directional valve that makes the noise the OP is describing if installed backwards
a gate valve is NOT a directional valve
Does NOT have flow arrows on the valve bodies and
will not make the noise the op describes
 
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LOL
How easy things can get misinterpreted.
I didn't want to indicate that you may have posted the wrong picture representing a gate valve, as the more important issue was whether it was a ball valve. The reason I say that is because either a globe valve OR a gate valve can chatter, whereas a ball valve would not. A globe valve does not have to be installed backwards to make noise. I have come across many with just a loose washer that cause noise.
But I'm not here to question you methods and/or to go off on tangents but to try to help the OP.

As I mentioned, "Not that I've seen very many water services but I've never seen a globe valve on a water service. I assume it was due to the inherent pressure loss thru them."

I understood quite well what you are saying. I just don't always understand the purpose of your questions. For example:
"question i have to ask

which way is the arrow on the valve pointed?

towards the water heater or away from the water heater?"

Please do us both a favor and don't make this a pissing contest again.:rolleyes:
 
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Diehard said:
LOL
How easy things can get misinterpreted.
I didn't want to indicate that you may have posted the wrong picture representing a gate valve, as the more important issue was whether it was a ball valve. The reason I say that is because either a globe valve OR a gate valve can chatter, whereas a ball valve would not. A globe valve does not have to be installed backwards to make noise. I have come across many with just loss washer that cause noise.
But I'm not here to question you methods and/or to go off on tangents but to try to help the OP.

As I mentioned, "Not that I've seen very many water services but I've never seen a globe valve on a water service. I assume it was due to the inherent pressure loss thru them."

I understood quite well what you are saying. I just don't always understand the purpose of your questions. For example:
"question i have to ask

which way is the arrow on the valve pointed?

towards the water heater or away from the water heater?"

Please do us both a favor and don't make this a pissing contest again.:rolleyes:
Click to expand...

I ask questions as a process of elimination.
A globe valve installed backwards makes a chattering noise because water gets behind the bib washer and lossens it.
The question. which way is the arrow pointing. if the answer is with the flow then it is not the bib washer chattering.
A globe valve pointed in the right direction will chatter AND WILL NOT shut off
The OP Did NOT indicate the vale would not shut off. SO common sense..it is not the bib washer on a valve pointed in the correct direction..THAT is eliminated
 
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