Hydronic floor heat......."Pressure Test"

[steel butcher]

I had an interesting weekend...starting up my floor heat. I have a "subray" style floor heat, tubes sandwiched between the subfloor and the finish floor. (Engineered wood floor).

Before, during, and after installation I had 70 PSI of air in the system.....held rock steady.

Saturday I flooded the tubes and purged the air. No leaks. Sunday I cranked up the heat and the @#$*#ing thing leaked after a couple of hours. (The garage below does not have a ceiling yet,so I could inspect it. drip..drip..drip)

I proceeded to demo 25 sq.ft of Maple flooring, there really wasn't much water. When I pulled the last board out, I found the problem. I had put a staple square into the tube.

To repair, I cut slots into the subfloor, brought the ends below (joist area) and spliced it together. I had just enough "extra" maple to put it back together. This part was amazingly smooth, you would never know what happened.

Apparantly the staple made a great seal until the pipe heated up and expanded.

So my quesiton is: What good is a pressure test?

[markwolf]

I am guessing a cement coated staple?The glue would hold until heated.I would not let that keep me from pressure testing though.I had to fix multiple holes in poured systems be glad you didn't have to chisel out concrete from around the tube without damaging it more!

[key]

I ran across this before. I found that if I relieved the pressure from the piping and re-introduce pressure at 20 lbs intervals. it helps in diagnosing a leak..


How come a A/C can hold vacuume a leak when pressurized?

Sometimes less pressure is better for testing. More pressure expands the pipe against a object that might seal the leak.

How come you can put a petroleum jelly coated needle through a balloon? (staple = heat friction = seal)

[Edited by key on 11-01-2005 at 08:24 AM]