The Pressure Loss Mystery

[CAMMShaft]

About 7 years ago while our home was being built I plumbed my attached shop with PEX for air. There are 9 drops in the walls/ceiling connected to my 80 gallon compressor. Unfortunately, I have a leak somewhere that I cannot locate. I am losing about 30-40 PSI in a day. I turn the compressor off at the breaker when I am done using it each day and up until now have had little pressure loss from one day to the next. I have done the soapy water test on all drops/joints that I can access, including crawling in the attic, so the leak must be behind the drywall somewhere. Any suggestions of how to find the leak?

I am in the process of building another shop which is detached. I was planning to run PEX again for air, but now I am having 2nd thoughts.

CAMM

 

[G1GRANDEUR]

you just answered your own question. no?

make little door or access panel, so next time it's easier to fix or check.

 

[The Cobbler]

is it possible a drywall or other screw went thru the pex?

 

[CAMMShaft]

you just answered your own question. no?

make little door or access panel, so next time it's easier to fix or check.

My question is if anyone has any tips for how to locate an air leak behind drywall.

CAMM

 

[CAMMShaft]

is it possible a drywall or other screw went thru the pex?

I have not put any screws in the walls in months (I don't like having **** hanging all over my walls) so I don't think it would be that. I wish it was so I would have an idea of where to look.

CAMM

 

[The Cobbler]

how about run some water in the line, drain it, pressurize with air & see if you can hear bubbling /spitting

 

[ghnl]

As Click & Clack would say, 'unencumbered by the thought process' but isn't there usually some sort of valve between the tank and the compressor? Could that be leaking/failing to seal?

 

[CAMMShaft]

how about run some water in the line, drain it, pressurize with air & see if you can hear bubbling /spitting

Interesting idea. To some degree, I suspect I already have some water in my lines/drops. While I would like to believe it that I built the system perfectly to avoid this, I doubt that is the case.

CAMM

 

[CAMMShaft]

As Click & Clack would say, 'unencumbered by the thought process' but isn't there usually some sort of valve between the tank and the compressor? Could that be leaking/failing to seal?

I have a ball valve between the tank and the PEX running though the shop. If I close the valve I have no pressure loss, so the leak must be out in the lines somewhere.

CAMM

 

[G1GRANDEUR]

My question is if anyone has any tips for how to locate an air leak behind drywall.

CAMM

I misunderstood, sorry. but again, just cut the drywall and install drywall access panel after fixing it.

have you disconnected air hose from the compressor and tested it's not the compressor for sure?

 

[CAMMShaft]

I misunderstood, sorry. but again, just cut the drywall and install drywall access panel after fixing it.

I have 9 drops throughout the shop, so I would just be randomly cutting them. With my luck I will find the leak after cutting the 9th hole.

CAMM

 

[larry_g]

Have you removed every device from the piping system like hose reels, blasting cabinet, or anything that is permanently attached to the pipes? Remove everything from the piping system that is not in the wall. Don't do everything at once though because you wantto find the item that is leaking, if it is something attached. Get a handful of small party balloons and put one over each QD sticking out from the wall. If one blows up then you've found a bad QD.

If the above doesn't find any leak then you'll have to open the walls. Good trouble shooting divides the system in 1/2. Somewhere near the middle of the piping system cut the pipe and cap the compressor side. That will tell you which 1/2 of the system the leak is in. Keep breaking the bad side in 1/2 and you will soon find the bad section. Basic Kepner Tregoe training.

lg
no neat sig line

 

[RTM]

Sonic listening device maybe? Seems like if the area was quiet, you might be able to hear it with something as simple as a water glass. But I remember a guy had something like these guys talk about.

https://www.airbestpractices.com/system-assessments/leaks/finding-and-fixing-leaks

 

[dalepres]

About 7 years ago while our home was being built I plumbed my attached shop with PEX for air. There are 9 drops in the walls/ceiling connected to my 80 gallon compressor. Unfortunately, I have a leak somewhere that I cannot locate. I am losing about 30-40 PSI in a day. I turn the compressor off at the breaker when I am done using it each day and up until now have had little pressure loss from one day to the next. I have done the soapy water test on all drops/joints that I can access, including crawling in the attic, so the leak must be behind the drywall somewhere. Any suggestions of how to find the leak?

I am in the process of building another shop which is detached. I was planning to run PEX again for air, but now I am having 2nd thoughts.

CAMM

There's a reason electrical junction boxes must be accessible. But that's very cool that you ran air around the house and not just the garage. I'd like to do that.

 

[CAMMShaft]

Have you removed every device from the piping system like hose reels, blasting cabinet, or anything that is permanently attached to the pipes? Remove everything from the piping system that is not in the wall. Don't do everything at once though because you wantto find the item that is leaking, if it is something attached. Get a handful of small party balloons and put one over each QD sticking out from the wall. If one blows up then you've found a bad QD.

If the above doesn't find any leak then you'll have to open the walls. Good trouble shooting divides the system in 1/2. Somewhere near the middle of the piping system cut the pipe and cap the compressor side. That will tell you which 1/2 of the system the leak is in. Keep breaking the bad side in 1/2 and you will soon find the bad section. Basic Kepner Tregoe training.

lg
no neat sig line

I disconnected everything one at a time and waited overnight each time. The leaking continued. I will try the party balloons. Great idea. If that doesn't work I may have to start cutting lines.

Sonic listening device maybe? Seems like if the area was quiet, you might be able to hear it with something as simple as a water glass. But I remember a guy had something like these guys talk about.

https://www.airbestpractices.com/system-assessments/leaks/finding-and-fixing-leaks

An ultrasonic leak detector sounds perfect for my situation. This will probably be a last resort as they are expensive. I wish I could find one to rent or borrow.

CAMM

 

[CAMMShaft]

There's a reason electrical junction boxes must be accessible. But that's very cool that you ran air around the house and not just the garage. I'd like to do that.

All of the drops are just in the garage. My wife would not approve of QD's sticking out of the walls in the house

CAMM

 

[Aquamoose]

If the coupler fittings are pointing down, get a glass of water and dunk ‘em in and watch for bubbles.


Sent from my iPhone using Tapatalk

 

[CAMMShaft]

If the coupler fittings are pointing down, get a glass of water and dunk ‘em in and watch for bubbles.


Sent from my iPhone using Tapatalk

Only the two in the ceiling are pointing down. I will try it with those. The other 7 are horizontal.

CAMM

 

[dalepres]

All of the drops are just in the garage. My wife would not approve of QD's sticking out of the walls in the house

CAMM

Air would be handy in the kitchen, in the pantry, maybe other places. A venturi vacuum generator would put your seal-a-meal out to pasture.

 

[Dustball]

Thermal camera while the compressor has been running for an extended period of time (warm air blowing out of leak).

 

[CAMMShaft]

Thermal camera while the compressor has been running for an extended period of time (warm air blowing out of leak).

I've never used a thermal camera before, so excuse my ignorance, but would it show the leak through the drywall? And I don't think it is leaking enough for the air to still be warm by the time it reaches the drops.

CAMM

 

[Retroman]

make little door or access panel, so next time it's easier to fix or check.

The lines are buried behind the drywall and he doesn't know where the leak is.
Its not a matter of "Putting in a little door" its a matter of where and how does he detect the leak.

Soapy water sprayed on the fittings that are sticking out of the wall?

 

[56Mark]

If it is not the QD's, then it is probably a crimp ring and not the pex itself. That limits the number of areas somewhat. Could you drill a small hole in the drywall near each tee/elbow and insert a tube to listen, or a microphone of some kind? At least small holes would be easy to patch. Where I used to work, we had an ultrasonic leak detector and I think that would work if you can find someone to loan you one.

 

[56Mark]

One more crazy idea. It would require drill small holes iin the wall at each drop, but could you put a little refrigerant in the line and use a sniffer type leak detector?

 

[Bigblockyeti]

I've never used a thermal camera before, so excuse my ignorance, but would it show the leak through the drywall? And I don't think it is leaking enough for the air to still be warm by the time it reaches the drops.

CAMM

Despite loosing as much as you are from an 80 gallon compressor and the volume of the plumbed PEX, I don't think you'd have enough loss that a thermal imaging camera would help, especially buried behind drywall. Another problem with this concept is air is heated when compressed, thus the reason why your compressor pump gets hot, air is chilled when decompressed, thus the reason an aluminum body die grinder gets so cold after running for a while.

There would be a temperature drop where the leak was and if significant enough (not there yet) a thermal imaging camera might actually be able to locate the chilled area even behind drywall. I would suspect a leak flowing enough to chill a wall cavity would be audible and loose far more air much quicker.

 

[Dustball]

I've never used a thermal camera before, so excuse my ignorance, but would it show the leak through the drywall? And I don't think it is leaking enough for the air to still be warm by the time it reaches the drops.

CAMM

It's hard to say if the leak is significant enough to show up on a thermal camera.

 

[Aquamoose]

Only the two in the ceiling are pointing down. I will try it with those. The other 7 are horizontal.

CAMM

Oh ok. Hope you’ll find the leak.

Another tip if you haven’t heard already, spray bottle with dish soap water.


Sent from my iPhone using Tapatalk

 

[Wrench97]

Leaks in a system that has been in place for awhile are usually at the couplers, reels or rubber hoses not the system it self.
I'm assuming you have no splices behind the drywall, so maybe you can plug off end of one drop at a time?

 

[CAMMShaft]

Leaks in a system that has been in place for awhile are usually at the couplers, reels or rubber hoses not the system it self.
I'm assuming you have no splices behind the drywall, so maybe you can plug off end of one drop at a time?

I hope you are correct. I am going to do further testing on each coupler and I hope to find my leak there.

CAMM

 

[Old Steamer]

If it is not the QD's, then it is probably a crimp ring and not the pex itself. That limits the number of areas somewhat. Could you drill a small hole in the drywall near each tee/elbow and insert a tube to listen, or a microphone of some kind? At least small holes would be easy to patch. Where I used to work, we had an ultrasonic leak detector and I think that would work if you can find someone to loan you one.

Something along these lines. Short of removing all the sheet rock, ultrasonic using test holes may be the way to go.

Thermal imagery such as FLIR needs a direct line of sight to properly work, sheetrock will prevent this.

 

[Bigblockyeti]

At the risk of making a bad situation worse, is there any way to over pressure your line to possibly make the leak more audible. I know you mentioned there's a valve between the tank and the lines, if they're already at a maximum of 175psi then that might not a good idea but if your compressor shuts off at a lower pressure or it is in fact regulated before entering the wall, it might be worth a shot.

 

[CAMMShaft]

At the risk of making a bad situation worse, is there any way to over pressure your line to possibly make the leak more audible. I know you mentioned there's a valve between the tank and the lines, if they're already at a maximum of 175psi then that might not a good idea but if your compressor shuts off at a lower pressure or it is in fact regulated before entering the wall, it might be worth a shot.

I currently have it regulated to 110 psi, so maybe I will crank it up when I am continuing my search for the leak.

CAMM

 

[Old Steamer]

This one has my curiosity up. OP, did you ever determine an exact cause?