Radiant Pex Pressure Check

[Gunslinger99]

I just got done installing the radiant tubing before they pour the concrete slab and am doing the pressure check now. I have been searching this site and other sites but I can't quite seem to find an answer for my situation. I'm hoping someone can help me out here...

I put about 80 psi of air in the lines yesterday afternoon (inspector wants 100psi but I didn't have an air compressor on hand at that time, used a tank), ambient temp gauge in my truck said about 87. Went back to check on it after dark and the ambient temp had dropped down to around 50 degrees and the pressure gauge on the PEX lines said about 60 psi. I put about 10 psi back in. I checked the pressure gauge this morning and it was down to 20 psi and the ambient temp was about 30 degrees. I didn't pay much attention to the temperature as I wasn't really sure that it mattered that much at the time.....

Not knowing much about this kind of stuff, from what I have read it appears that changes in ambient temperature will affect the pressure in the tubing. If this is correct, then is the pressure change that I am experiencing normal? Seems like if there was a leak I would not have any pressure left in the lines this morning, right???

Thanks in advance for any help with this.

 

[Highbeam]

Leave the air pressure in there and see if it goes up as the ambient temps go up.

 

[custom1]

Temp will affect the pressure but not that much. I would say you have a leak. Mine did the same thing. A slow leak will take a long time to get to 0. How are your lines connected? Do you have a manifold or did you just connect them together temporarily? Spray some soapy water on all your connections. Watch for SMALL bubbles. I have a Manifold from Blueridge and it had a couple small leaks where the ends thread on.

 

[Gunslinger99]

I just have them hooked up temporarily, no manifold yet. I will try the soapy water and see if I can track it down. Thanks!!!

 

[brewchief]

Check your gauge connections first, I've found more then one that leaked.

FWIW a 2 gallon pump sprayer with soapy water works good to cover a lot of pipe fast.

 

[Highbeam]

Pressure testing your pex before the pour might not be that important so long as you have no joints in the floor. From reading on teh net, it is very unlikely that you'll have a leak in the continuous loops. Pex is pretty is pretty tough stuff and you would have to really try to puncture it.

I'm also pouring this weekend and I don't even plan to pressure test the lines.

 

[anthony666]

if you're bringing your pour in via wheelbarrow it would behoove you to fill it with 50 or 60 psi .. if i had a nickel for every time some gorilla burst my pex by pinching it with the lip of a barrow i'd be able to put gas in my truck .. at least that way when the concrete volcano goes off you know where to couple it instead of cursing & bashing away at a vast slippery stain with a pickaxe after the fact

 

[plumbstupid]

Check the schrader valve on your gauge, about 40 % of the ones I get leak.

 

[Gunslinger99]

Where is the schrader valve?

 

[jhelrey]

Looks like a valvestem for your tire

 

[Gunslinger99]

Thanks! I took the pressure gauge off and re-applied the teflon tape using more then I did before and that seems to have stopped the leak.

They poured the slab yesterday and the pressure held. I feel much better having the tubing in-bedded in 4" of concrete. Hard to hurt it now.....

Thanks again everyone!!