Air in pipes

[Gehrkmania]

Hi all,

Over the weekend, we started getting air in our pipes and I can't figure out where it's coming from. Here are the pertinent details I can think of, but let me know what else would help diagnose the issue:

• City water
• Gas water heater (located in basement)
• Copper pipes inside the house, pex from water meter to the house
• We have an expansion tank installed off the water heater
• Possibly/probably failing PRV (I have a new one, just haven't installed it yet)
• With all faucets shut off, no activity on water meter and no mushy front yard above water supply
• The city water company said there hasn't been any work done in my area or leaks reported

I can bleed the whole house and wait 15 minutes or so, and the air is back. I don't see any water leaks anywhere and am wondering if it's possible for air to get in without water getting out somewhere. After I shut off a faucet, I can hear a hissing sound in the pipes for a few seconds, like the sound it would normally make when the toilet tank is refilling, but only for a few seconds.

Is it possible for a bad PRV to allow air into the system without water leaking out?

Let me know what other info you'd need. Thanks very much for your time and any help you can provide!

 

[SHEPLMBR]

After purging air from lines do you run water in faucet from furthest faucet for a while?

 

[Gehrkmania]

Well, I think I've run the water in all of the faucets for 2-3 minutes each. When you say furthest faucet - do you mean the one that's furthest away from where the water comes into the house?

To make sure I'm purging the air correctly, what is the right procedure for that?

Thank you!

 

[Gehrkmania]

Update - a guy from the water company came by this afternoon. He checked the fire hydrant at the end of our driveway and it seemed ok. But, he pointed out that there is a very slow movement on the water meter when all of our faucets are off, indicating that water is flowing somewhere, albeit very slowly.

 

[Diehard]

Hi all,

Over the weekend, we started getting air in our pipes and I can't figure out where it's coming from. Here are the pertinent details I can think of, but let me know what else would help diagnose the issue:

• City water
• Gas water heater (located in basement)
• Copper pipes inside the house, pex from water meter to the house
• We have an expansion tank installed off the water heater
  
• Possibly/probably failing PRV (I have a new one, just haven't installed it yet)
  
• With all faucets shut off, no activity on water meter and no mushy front yard above water supply
• The city water company said there hasn't been any work done in my area or leaks reported

I can bleed the whole house and wait 15 minutes or so, and the air is back. I don't see any water leaks anywhere and am wondering if it's possible for air to get in without water getting out somewhere. After I shut off a faucet, I can hear a hissing sound in the pipes for a few seconds, like the sound it would normally make when the toilet tank is refilling, but only for a few seconds.

Is it possible for a bad PRV to allow air into the system without water leaking out?

Let me know what other info you'd need. Thanks very much for your time and any help you can provide!

"We have an expansion tank installed off the water heater" Assuming it has an Air Inlet Valve, have you ever checked the air pressure in the tank?

Is it possible for a bad PRV to allow air into the system without water leaking out? No more possible than any other valve or device in the system.

When purging each individual valve, allow water to flow at a relatively high flow rate to help carry any trapped air through. And as SHEPLMBR said, "from furthest faucet for a while".

 

[Gehrkmania]

OK - so today was plumbing day. I drained and flushed the water heater, replaced the PRV and charged up the expansion tank. The tank was down to around 20 pounds of pressure, so I upped it to around 65 pounds.

So far, everything seems to be working fine. Fingers crossed that the new PRV and/or adding air to the expansion tank has fixed the problem.

Thanks all for your help - Happy Thanksgiving!

 

[Diehard]

OK - so today was plumbing day. I drained and flushed the water heater, replaced the PRV and charged up the expansion tank. The tank was down to around 20 pounds of pressure, so I upped it to around 65 pounds.

So far, everything seems to be working fine. Fingers crossed that the new PRV and/or adding air to the expansion tank has fixed the problem.

Thanks all for your help - Happy Thanksgiving!

The reason I asked about the expansion tank air pressure was because I was speculating on possible sources of air. I was thinking that if by chance the diaphragm ruptured, the air could get into the water. Although I doubt that condition would last very long, without showing other signs.
I assume you checked the air pressure with the water off and the water pressure relieved.
Interested to see if this does, in fact, help the air problem in the long run.
Happy Thanksgiving!

 

[FishScreener]

The expansion tank should charged to just under the system pressure. If you set your PRV to 60-psi, the expansion tank to about 58-psi.

The fact that your meter is running indicates a leak somewhere. When water runs across a leak, it can form a Venturi effect, creating suction which can pull air into the system. Look up “chemists aspirator”.

 

[Diehard]

The expansion tank should charged to just under the system pressure. If you set your PRV to 60-psi, the expansion tank to about 58-psi.

The fact that your meter is running indicates a leak somewhere. When water runs across a leak, it can form a Venturi effect, creating suction which can pull air into the system. Look up “chemists aspirator”.

The leak was mentioned as, "a very slow movement on the water meter." Doyou think that would be sufficient to create an venturi affect?

 

[FishScreener]

Depends on where it is. You need a velocity increase and fall.