Can pumping away pull in air

Unknown

A fellow tech asked me this question . Call it a 4 zone boiler , circs are pumping away from the expansion tank and fast venting B+G EAS . Pressure around 15 psi . What if all 4 zones came on at once when the low limit is satisfied ? Can air get sucked into the system through a fast venting air eliminator ? Thanks in advance . Ron

DanHolohan

No.

Josh_10

Ditto NO...

Unknown

Nope,nope,nope.....

Unknown

Just to be clear ....

I see a common theme in the responses , thanks guys .

OK , next question . Can air be introduced through the scoop at very low pressure in the same scenario ( all pumps on at once ) ? Could it happen at low pressure with the expansion tank downstream of a circ ? This is to help out a serviceman buddy , so if anyone can elobarate on a response , I'd appreciate it . I have Dan's " Pumping Away " somewhere here but I can't seem to locate it .

Steamhead (in transit)

Not

as long as the system fill pressure is above atmospheric pressure.

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DanHolohan

That's right.

Unknown

Thanks Frank

That was my answer , the system pressure has to be subzero at the airscoop to introduce air . But he was wondering if multiple circulators turned on at once can bring it to subzero at the scoop if it's close enough .

Cosmo_3

The reason why this cannot happen is that even on the suction side of the pumps, you still have pressure. A circulator is a pressure differential device, however you must not forget that the hot water boiler should be set to at least 10-12psi and if you were to install pressure gauges before and after the pump you would read a higher pressure on the discharge side compared to the suction side, but there will be some pressure on the suction side. The air purger will never see a below atmospheric (vacuum) condition.... lets assume standard sizing practices were maintained to size the main (primary) piping.


Cosmo Valavanis