Air testing mains

Tom_133

I have 3 floors of copper mains, some sweat, and some pressed, each floor is 300' of pipe. I air tested, and everything was good. So I came back a month or so later, and now it wont hold air!!
Of course its all insulated so finding that leak or leaks will be rough. I do have each floor isolated with ball valves, so I can at least narrow it down to which floor has the issue.

I was thinking about trying to smoke the lines so that it may help me find the problem. Any ideas on how to track it down without water from any who have had this happen would be great. Thanks all.

Alan Welch

If you put air pressure back in the isolated zones ,and walk around,  you will probably hear the air leaking out..When we use to rough in new houses with baseboard  heat,, we would stub out the supply and return piping at the boiler location and leave under pressure.  Then if another contractor put a nail, screw or nick into the pipe they knew right away.

Tom_133

It definitely had air in it. This is a relatively large commercial job. Sheet rockers painters electricians plumbers they’re all in there right now. More than likely if somebody hit it with a nail or nicked it, they are not saying anything. The fact that I have insulation on it makes it very tough to hear a leak. I was thinking about putting some smoke by the compressor near the air inlet so that possibly I would see it? Only other idea would be to add maybe a couple gallons of water, perhaps the water may push out the leak and wet the insulation making it easier to find?

dopey27177

You can try putting in a very small amount (use an eye dropper) of oil of wintergreen in the piping with the air pressure, if there is a leak you will smell it.

EBEBRATT-Ed

Seeing that you tested it it's probably a decent size leak that someone put a nail or screw in it. When you find the leak you will know who did it.

Never used oil of wintergreen but that sounds like the way i would go

realliveplumber

If the nail or screw is still in it, it might be a small leak.

Put some detectable gas in it, and use a leak detector. You could isolate sections of the insulation by removing one section of it, and sniffing either side under the insulation.

ratio

With linesets concealed in the wall, I've in the past left them under 600 lbs N₂. They'll know pretty quickly if they catch the copper!

Start out running it up with N₂ as high as you feel comfortable, & watch to see how fast it drops. There's a chance you'll hear the leak. If you can't hear it, add some refrigerant & run it up tight with N₂ again & start sniffing. You may be able to get by with just sticking the probe under the insulation—the refrigerant should (mostly) stay inside the jacket.

Tom_133

These are heating mains, 3 floors of 11/2" copper down to 11/4" about 300' with insulation and around 36 tees per floor. With nearly every trade making a horrendous amount of noise, I promise I WONT hear it. I guess I will just try the wintergreen trick, I only have peppermint on hand hope that works. Then if that doesn't work it will be the detectable gas. I will isolate and hope its not in the 2.5" mains going from floor to floor

kcopp

Any chance to to go back at night? or really early?

Tom_133

Kcopp, thats my plan if the smell test doesn't work today! Hey actually aren't you in NH or somewhere close by...

kcopp

Seacoast NH

hot_rod

And at some point you may need to put water in it. A nail or screw in a pipe can be very hard to find, very slow leak down in a large system like that. Until the nail rusts away

Is there a Leak Busters franchise near you? They have a truck full of leak detection options, I've used them on large snowmelt detection and they pinpointed the tiny leak.

Tom_133

Yesterday I filled it with 80psi and it sat with that for 3 hours... this makes me insane. Its possible another trade thought they were being funny, but its also possible I have a slow leak. If it holds 80 for hours the leak is so slow I will be filing with water and looking for a small drip. Thanks all

hot_rod

Water is a good idea, as it may wash some flux out of a questionable solder joint and better show a leak. Water may be messy but it usually shows a leak quickly.
Keep your compressor or shop vac on hand to evacuate with the least mess.

mattmia2

Does this by any chance involve any propex?

Tom_133

nope, sweat and propress.