Air leak in radiant system-looking for help

[bigred292]

It's time to install the radiant floor heat!!! Hurray!! Been waiting since December!!!!
Installed vapor barrier, 2 inch Dow board on entire floor, plus 1 1/2 foil face board up the sides of the walls with the top cut at a 45 to floor level.
First question I have is how or where to put this across the door openings?
I'm wondering if you can do it across the door without cracking the concrete- I know there's a way out there- just looking for help.
Second, all piping installed today- 7/8 pex . Hooked it all up and did the pressure test. My installation guide says to fill it to 50 psi- If you lose more than 5 psi after "several" hours then you need some adjutments.
I filled mine today at noontime at 50 psi.
It went down to 45 about an hour into it but held at that til I went to work at 2:00. Just got home at 11:00 and the gauge is showing 36.
Is this too much of a drop over the course of 11 hrs? Should I re-test it?
I just don't know what they consider several hours.

 

[koditten]

The door opening on mine is just a 6" strip of dow board between the main floor and apron(out side concrete pad.) I bridged the foam with some threshold material and glued it down. Seems to be holding up just fine. My concrete pours were in 2 phases so the foam is my expansion material and heat transfer seperator in one. I do have pins to make sure the 2 seperate concrete pads will not lift independent of each other.

As for the leaks, did you use any soap/water solution to test for leaks in your pex tube? It is highly unlikely that you have a leak in the pex. It is always seems to be the connection between the pex headers and pex tube. The soapy water will find the leak quickly.

Good luck, you are going to love the system.

 

[bigred292]

Thanks for your reply- I was talking with the guys at work today and someone mentioned the soap trick- can't remember how many tire beads I checked like that working at a gas station when I was 15!
Did it as soon as I got home and worked like a charm! Both returns needed a little tightening. Filled to 50 psi about 2 hrs ago and no drop.
As far as the insulation that's kinda what I was thinking. So you poured your floor all the way to outside face of wall then insulated it there? If that's the case the foam is actually on the exterior?
Once again guys at work said I was being **** but I'd rather do it right the first time.
Thanks for your help!

 

[raspy]

bigred,

You really don't want ANY leak in the system at all. But, the drop in pressure you noticed might be at a joint at the manifold or other piping and not in the tubing itself. Air leaks far easier that water, so if it's just a leak at the threads, or something above ground, no problem. The tubing is very good and will not leak unless it's been punctured by rough treatment, a sharp edge, or something. Also, pressure changes with temperature overnight or during hot days.

You said it was 7/8 tubing. I think you mean it measures 7/8" OD but it is called 3/4" PEX. This is very tough stuff and hard to puncture.

Don't worry about leaks above the pour. We test all out layouts at 100 PSI according to code, but often have a slight leak somewhere that we get to later when hooking up the boiler.

 

[Frank The Plumber]

Generally when using an air compressor to test lines you will have a slight temperature elevation due to heat generated by the device. As much as a 5 pound loss can be considered normal. But then it remains at that 5 lb loss and may even rise if the lines warm. At a 15 psi loss yours is not. You need to isolate the device from the test run with a good and positive valve, you can not just leave it attached to the compressor with no isolation.

Mix a 50% joy or dawn and 50% water solution, mix well and put it into an old spray bottle, adjust it to mist, repressurize and soap soak all of your connections. If you continue to see a drop, sap test all of your footage and fittings. Lines and fittings can and do have defects and can cause troubles. Be persistent. It's well worth doing a proper test.

 

[bigred292]

Thanks for all the advice- I did do the soap trick and found where the leak was.
Hasn't dropped at all in 1 1/2 days.