PEX system leak. How do I find it?

Designie · Sep 17, 2010

I have just finished roughing out the plumbing on my new house using PEX. I did a pressure check on the cold using a gage and ran it up to 60 lbs. It held the whole day and then was down only a couple lbs. in the morning, probably due to the temp.

When I checked the hot I ran it up to the same 60 lbs, and within about 5 minutes it had lost a lb or 2. So i waited a while and sure enough, it was down about 5 lbs. So I re-pressurized it to 80 lbs. and waited. It is losing pressure at about 10 lbs. an hour.

I tried listening for a leak and checked every valve and fitting and could not audibly find a leak. Is there some technique I can use to try and locate where I am losing pressure?

Thanks!!

Redwood · Sep 17, 2010

I use an ultrasonic leak detector when testing with air. It picks them up from about 20' away.

Sponsor · 2022-01-29T12:20:58-0800

Jadnashua · Sep 17, 2010

This is where a manifold system makes life easier, you can shut off individual branches to help isolate things. One of the pros must have run into this, and may have some ideas.

Designie · Sep 17, 2010

I have it set up as a modular system, with each room on it's own 3/4 supply lead with a valve. So I can start by closing all but one zone, then check pressure. I still can't believe that I can't hear the air. I put my ear right next to every fitting I have!

NHmaster3015 · Sep 17, 2010

Crank the pressure up to 125, you should hear the leak then

hj · Sep 17, 2010

Turn the water on. Or use soap suds on the joints.

Jerome2877 · Sep 17, 2010

Yep water will be easier to find! lol Maybe Isolate first then turn water on and look for leaks.

Winslow · Sep 17, 2010

why not just charge the system with water, it's not like you're going to have to solder to repair the leak and the leak will become self evident.

NHmaster3015 · Sep 18, 2010

That part where the leak is an uncrimped fitting might not be much fun when water blows it off

hj · Sep 18, 2010

If it is uncrimped, air pressure would have already blown it off.

Ballvalve · Sep 18, 2010

I would never go anywhere without a 1 gallon pump up sprayer filled with 90% water and 10% dish soap. Instant tire, gas, pipe, leak detector on the cheap. Damn handy portable sink on the job too.

Keep another one with diesel for parts cleaning, and a third with bleach for cleaning up the nasty stuff.

hj · Sep 19, 2010

I just buy the quart bottles of kid's bubble solution from the dollar store. The glycerine in it makes the solution stick to the joints a lot longer than soap, so even a very small leak will usually be very evident after a few minutes.

NHmaster3015 · Sep 19, 2010

And.... it costs a lot lest than a bottle of megabubble

Designie · Sep 20, 2010

Well, I was able to locate the room with the leak. I closed each room's supply valve and it was the last room on the line, the master bedroom. So I have isolated the room, but still have not found which fitting has the leak. So it has to be one of 2 vanity supplies, tub supply (which has a test plug installed) or the shower valve connection (or valve itself).

hj · Sep 20, 2010

You are assuming that you only have ONE leak, which might not be a valid assumption.

PEX system leak. How do I find it?

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