baseboard hot water noise

[sean_sarah]

My baseboard hot water system was drained during the summer while remodeling the home. In November I restarted the system but have been unsuccessful in eliminating the gurgling noise. The system is not zoned but does have a loop which runs upstairs and a loop for the ground floor. The boiler is on the first floor (no basement). Only one of the radiators in each of the two loops has a bleed valve. I've made numerous attempts to bleed the system. If I shut off the upper loop (manual in line valve) I am able to operate the lower loop gurgle free. When I attempt to bleed the upper loop I am unable to get the air out and in fact the gurgling seems to increase. I get plenty of heat in both loops.

I manually shut off the auto feed and let the system run for a week in this condition looking for a pressure drop but there was none indicating to me that I didnt have any leaks. I don't understand why the bleeding seems to worsen the noise.

In trying to figure this out I discovered that the expansion tank (extrol #15) appears to be installed in an unusual way and am wondering if this is part of the problem. The outlet on top of the boiler where the PRV is installed has a Tee and the tank is attached to the top of this TEE. The tank is upside down (schrader valve at top/writing upside down)This seems wrong in that there is no way to evacuate the air in this dead end configuration. It seems that the wet side of the diaphragm will always have a pocket of air underneath it. It is also noteworthy that when I shut the boiler down in the spring I noted it was running at a high pressure (29-30 lbs) which is right on the border of the PRV. I'm wondering if the previous owner ran it this high and kicked the PRV essentially bleeding some air under the expansion tank and quieting the system. Does this tank configuration sound wrong to anyone?

Any suggestions on quieting this system would be appreciated.
Scott

[Ed Imeduc]

When I attempt to bleed the upper loop I am unable to get the air out and in fact the gurgling seems to increase. I get plenty of heat in both loops.

Do you get water out of here with the pump off????
Do you get air or water out of the expansion tank schrader valve??

ED ;)

[sean_sarah]

I get a tiny bit of air followed by water when I bleed from the upstairs loop when I turn the pump on and bleed it spits air and water as the water circulates and the gurgling increases indicating more air is circulating. I'm unsure as to where this air is coming from.

When I depressed the schrader valve just now it gave me a spit of water follow by air. Has the tank failed? I don't see a significant increase in pressure when the boiler is hot (maybe 1 psi tops).
Scott