I finished running the 300' of PEX tubing + an additional 25'. I put together a little pressure test jig, which allows my to pressurize the tube to test for leaks. I did this and pumped 20 lbs. or pressure into the tubing. I found that it loses about 10 lbs/hour. Does this mean I have a leak in my tubing (or test jig) or is this normal?

I would thing something is leaking. It should not drop at all.

Seems like a weird flooring question, but you should be able to put pressure on the line, and hold it with no drop for 24 hrs before you consider yourself to have passed the test.

Ron

When an intertube has a hole, does it hold pressure or lose pressure?

No hole. I just tightened up the fittings and viola, it holds pressure. I have it pumped up to 30 lbs right now, and it seems to be holding. I am thinking now to get it hooked up to the furnace before putting the floor down. I just don't want to take any chances.....