Originally Posted by
stickman42
I'm assuming you have a closed loop and a non-pressurized flow center like a B&D brand. This is what I have. My reservoir has a screw-on lid which seems to tighten enough to keep loop fluid from escaping. If your loop was properly filled in the beginning, I would think that air could only enter the loop by replacing lost fluid. The only logical place I could see that happening is in the reservoir. From what I've read, the loop pipes do expand and contract, which would cause the level in the reservoir to fall and rise.