locate pex freeze damage

marcy

Two years ago I built a 20,000 sf building and installed a radiant system with heatlink pex in 4" concrete on top of 1-1/2" decking. Nightmare of nightmares, the pex was allowed to freeze before it was hooked up to the boiler. I had about 10 or so leaks that were chiseled out of the concrete and the damaged pex was cut and replaced with couplings. I finished the floors with an acid stain and a clear epoxy topcoat. A few months ago I noticed that the epoxy was clouding up in certain locations directly above pex locations. My experience with epoxy is that this indicates moisture. I suspect that during the freeze, the pex distorted just to the point of breaking but stopped short. Now two years later, with natural expansion and contraction of the concrete slab, the thing finally gave. I have numerous stripes of blistered epoxy and over the past 4 months they appear to have grown. I have no indication of any leaks on the ceiling below, however there is a 3 foot cavity with insulation. I am trying to figure out how to determine if I actually have a leak without chopping up my finished floor. I have disconnected the suspect line and pressurized it with air to 39 lbs. The next day it dropped to 38 and a week later it was down to 34 lbs. Do you think this is the best way to test this line or do you have another suggestion or scenario? Also, if it is a leak do you have any ideas how to pinpoint a location? Any help to this dreadful dilemma would be appreciated

jalcoplumb_2

could be leaking

but the epoxy could be reacting to the heat and changing color.

I hope it is the latter.

Good Luck,
Joe

Rick Kelly_3

Leaking PEX

While you might have some leaking PEX, a few other things need to be confirmed. When doing an "air" pressure test, your only indication of a leak/ no-leak situation is to trust in your gauge. By doing a hydrostatic test (pressurized water), should you experience a loss of pressure, it should be accompanied by some evidence of dripping water or at least some wet spots.

Another possibility for those "stains" is that you might have a phenomena known in the business as "striping".
Striping is usually caused by excessive heat localized above the embedded tubing. Your slab floor temperature should never exceed 85 degrees in most applications. Check that. If your floor temperature is much higher than that, what you might be seeing is a heat induced chemical change to the dye and/or epoxy finish.

Concrete is a lot more porous than it seems. If you have a very slow leak, it wouldn't be out of the question for the small amount of leakage to evaporate before you would ever see any wetness.

Another thing you can try easily is to close your make-up water valve to your system, note the system pressure with the power off (should be approximately 12-15psi), and observe over a few days whether or not you lose system pressure. If you do, you might just have a leak problem. Keep in mind to look elsewhere in your system for any other evidence of leaking before making a final determination.

marcy

continued

i don't think the epoxy is reacting to the heat because this is one of the few areas where this has occured-if that was the case, i would expect to see it elsewhere in 20,000 sf of this stuff. i neglected to mention that when i pressurized the loop, i left the water in. i did check to see that the gauge and fittings were not leaking when i set up. i will check the temperature and double check to see if the gauge is leaking too. i like your idea about the make-up water valve. if i have a slow leak, how much pressure would you expect to lose over a few days? thanks for the input.

Dave Faust

Refrigeration guys use dry nitrogen to leak test. It dosn't make a mess, and it dosn't react to heat gain or loss by changing it's pressure. They also use a negative pressure created by a vacuume pump, but this might draw in too much contamination.
As far a pinpointing, didn't I read somothing about having a cat lie on the warm spot? or water evaporating first from the area directly above the leak (if the water is hot)? Couldn't thermal immaging be used for this?
Good Luck.

jerry scharf_3

Time to call in pros

Marcy,

There are professional leak locater services. Given the value of the finished floor, it seems like it's worth the call.

If it weren't epoxy sealed, I would suggest high pressure helium with a sniffer, but that's not going to work with the sealer.

Also as a lesson for the future, when a situation like this occurs, you need to get a fairly long no questions repair clause added. If you stressed the pex enough to get leakers, you can bet there are other areas that were stressed to within a few % of leaking... The radiant contractor and general might balk at first to such a clause, but a cold stare and the simple statement "OK, then rip it out and start over" will usually bring them around. There is a certain type of contractor that all to often try to make their mistakes the homeowner's problem.

just my $.02

jerry

Weezbo

Marcy, i have seen this with older systems (not pex)

these systems were installed to never reach out of 100 degreesF....unfortunately due to unforseen memory lapses maybe people didnt pay thier fuel bill or whatever or werent on automatic fill or, whatever the cause, you choose...thing is instead of leaving the controls alone and pumping in surface BTU's to thaw the place out the "plan " was to try Jacking up the temps....i have also seen this when there was no apparent limiting devices on temps to the systems..this also can cause what you "see" in the pictures you have offered ....now sometimes a leak in an area will follow the pipes going along the outside pipe wall a ways before finding its way out some where ...the thing that i found to be rather remarkable on some leaks is that they werent consistent....what i mean by that is,not every time the zone opened or closed would the leak become apparent.! now that is probably because of the temperature of the water somehow changes the variables just enough that the leak expands shut or something in the pipe collapses and relaminates enough to slow the leaks...all i can honestly say is that i havent seen the pipes always leak through the concrete at the break...so, i might check the zone you are thinking is the culprit at the point it enters and leaves the slab also..i have also seen what people Thought were leaking slabs only to point out parts on the headers or valves that were the cause of the leaks....specific locations under an epoxy coating...well, spectography ,ultra sound and maybe a tool that is a didgital moisture sensor might be the best places to start ...i am fortunate so far the leakers can be directly attributed to Nails ,hilti;s concrete blades,big drills,sheetrock screws and carpet tack strips oh an one roofing staple dont even ask ...........one other thing Add foor colour to your boiler waters ...bright cherry red or cool blue...then if you have surface leaks it will more easily be caught..*~/:)