Plumbing question

[Charlief]

I'm getting air in my hot water line when the system is not used for several hours.   Turn the hot on and it will spurt and spit for a few seconds then run fine. I've run just the cold side and that's fine.

At first I was thinking my well pump or the expansion tank was on its way out. But with just the hot doing it ......I figured those are fine.

Hot water tank (electric) is about 10 months old. No leaks or any other problems. 

Any ideas?

Could it be this thing on the  cold water feed of the water heater? It looks like some kind of pressure/vacuum valve. It's got some corrosion on it so I just might replace it and see if that cures my problem.

Thanks in advance for the help.

[The Architect]

Can you check the temperature of the hot water.

I wonder if there is air stuck somewhere in the line. Have you tried running all the hot water faucets to flush out the air?

[Charlief]

It happens on all the fixtures.  The temp seems fine. 

[The Architect]

That fitting looks like a fancy pressure relief valve.  I don't think it's letting air in.  Those typically leak due to failing seals.  It would be impossible for air to get into the system without water getting out first.

Do you have a radon system?

Could the coil in the water heater not be working right?  Could it be causing water to boil around the coil and create air?  Have you tried lowering the water temperature?

That's all I've got.

Good luck. 

[Speeddog]

This doesn't appear to be directly on point, but may lead you to it:

http://www.ehow.com/how_7586557_air-water-service-shut-off.html