after doing some reading it seems the system is likely drawing in air (or drew it in at one time).

I tried opening multiple valves manually and quickly turning on the main to 'sweep' out the air - that didn't work.

tonight I connected the system to compressed air at 50psi. It didn't hold - comp refilled but no noise of leaks.

Any ideas??????????????

davebarnes21, if you pump water into the system when all the valves are closed, water hammer is to be expected; if this is done regularly a fitting will fail soon. How did all that junk get into the system? Did you not flush it?

It's a new system and I am having troubles with a certain valve. I have since corrected that problem.

There wasn't an extraordinary amount of debris in the system, just some pebbles in one spot. The shop vac was overkill.

When I fill the system at the main shut off I do it slowly. So I don't slam it with water.

Its air hammer and I can't get it out - would blowing down the system with air and then filling back up help?

I guess my question is this:

Could running the shop vac (suction) on a valve create a seepage in a fitting that only lets air in - underground and, if so, do I have to dig it up? How do I find that leak? etc...

davebarnes21, I got a little confused over the terms 'air hammer' and 'water hammer', so I 'googled' each and found some information which might be of more help to you. I'd be interested to know how it all works out. Thanks.