pressure testing hydronic system with air

Kevin O. Pulver_2

that all our tubing must undergo 100 PSI hydrostatic test before pour. So far, I haven't done it and they have left me alone.
My reasoning? I don't have any control over when this building will be framed, closed in, electricy and gas ran in, and when Winter will hit Nebraska this year.
What if my slab is frozen solid before then?
If it will hold 60 PSI air, it will hold 12 PSI water. Also, what if a sweat joint has a leak and needs to be repaired? It's much more fun to just let the air out than dry to drain the water. Kevin

Rich Davis

Somebody asked me, and I couldn't give a good answer. Why can't you pressure test a hydronic system with air to test for leaks. Say to just under 30psi the only thing I could think of would be that you would have to block the air scoop and the pump might leak. Could anybody help with this.
Thanks

Terry Trommeshauser

why use water?

Water won't compress. Air will (potentially dangerous)
There are prob. more reasons to use hydrostatic testing w/water instead of air - but this one is why we use water (on systems)

now if we're testing infloor tubing only, we will use air, not water - simply because a leak during the pour can be repaired w/o affecting the pour, whereas a leak with water will soup up the concrete in a hurry. And it's easy to see the bubbles

Brad White_185

Pressure is pressure...

Personally, I do both. Air pressure to find more obvious leaks (soap bubbles or a good hissing if I see a drop in pressure) and if there is a water leak requiring a joint be re-soldered, it takes a lot less time to do that to dry piping.

Air leaks are a lot neater...

Where air does fall short is in the compressibility department as Terry pointed out. The limitation is that if left over-night and the system cools, you will show a slight pressure drop. (Water will do this but less so.) Point being, it may lead to to try to find a leak you do not have, or if you write it off to "temperature differences only", that may mask a real, albeit slight, leak.

The up-side is, if you fill a system with air when it is cold, it warms and the pressure increases, you are in good shape. A rise and fall with temperature is a good indicator.

I always finish with a hydro-test to twice working pressure but as stated, be careful to isolate air vents, safety valves and certain panel radiators. (I turned a couple of Runtal vertical panel radiators into air mattresses. They heat well enough but look as puffy as Bridgette Bardot's lips lately.)

Unknown

Brad, puffy lips ?

Brad, thought u were getting married and u still allowed to say puffy lips?

Brad White_185

Yes and Yes, Ray

Both are true.

Now behave!

Mike Thomas_2

ultra sonic leak detector

When installing new systems I pressure test with air and then listen with an ultrasonic leak detector. I can spot a leak in minutes with it. Just bleed off the air and repair the leaky joint..

Gary Reecher

In the Air Force we had to hydrostatic test repaired engine bleed air ducts. Leaks were easy to spot but being curious one day we air tested one that failed the hydrostatic test. We found that the pressure gage would drop quickly on ducts with leaks when doing the hydrostatic test but when testing with air the drop time would be longer.

Imam

Testing a new hydronic system

I am pressure testing a new hydronic system with air. From day one before any pour I could not keep air in the system for more than a few hours. Snoop checked all joints and tightened.  Now I do not get any bublles but I still cant keep air in for any amount of time.  All runs are start and finish at the headers. Can there be small leaks that I can't detect with soapy water?

Mark Eatherton

Options...

If you do a water test, you WILL see the leaks.



If you do use water, be certain and purge the water out with compressed air when done.



If you use air, purchase or borrow an ultrasonic listening device that will take you to the leak.



Sometimes, the O rings on the ends of the tube connections to the manifold get nicked and lose air, but when you hit it with water, they seal up. Sometimes...



ME