Help! I have to keep purging 2nd floor zone


Old 02-01-08, 04:34 PM
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Unhappy Help! I have to keep purging 2nd floor zone

I have a closed loop forced hot water heating system with four zones. The 2nd floor zone keeps getting cold and I have to purge the air out of the zone over again each day to keep it heating. I just installed 3 days ago in the highest point a SpiroTop air purge valve, it seems to work, I do hear the air releasing, the reason I installed this valve is to get rid of the waterfall sound in the pipes when heat is circulating. It was working ok before I installed this Spirotop, there are no leaks, my system is ok on the other zones. I have to purge the air from the Thrush Co. purge valve in the cellar which is above the circulators, the circs ae on the return line, it seems to always get air pockets !
I installed last year on the same zone near the boiler a Spirotherm air eliminator but it never seemed to work, it was a used one from a neighbors heating system, and I never heard anything purge or hiss from this inline Spirotherm valve. My Boiler pressure is around 20 lbs, its a Weil Mclain 468 with the old style ceilng expansion tank, I give up !!!

I had the hardest time to purge the air out and get circulation in the zone. I manually filled the system to 25 psi and it seemed to purge after that, I filled the system after purging to 25 psi to see if that helps, maybe I needed more water in the system, but it happened again today, and the expansion tank is more active than before, so I guess there is ore water than it needs.
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Old 02-02-08, 09:09 AM
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Air problems

You said the expansion tank is more "active" than before increasing the pressure. What do you mean by "active"?
In general, automatic air vents & conventional expansion tanks are not a good mix. What happens if you turn off the make up water? Does the pressure drop?
Old 02-08-08, 07:49 PM
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air problems

If you hear a "water fall" you have too much air in the system . I would replace the "used" auto vent you have with a new one or better yet install a rad. bleeder at the highest point and bleed it manually!
Old 02-09-08, 07:06 AM
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PipeD, what Grady said about auto air vents not generally being used on a system with a conventional (non-bladder) type expansion tank is because you don't want to eliminate the air ... If you do that, the tank will eventually become water-logged and cause the relief valve to open.

The system should be designed so that the trapped air is sent back up to the tank where it belongs.

On a system with a bladder (or diaphraghm) type tank you DO want to eliminate the air because it has nowhere to "hide" and serves no other purpose than to cause problems.
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