steam boiler sucking air

joecorn

I have a weil mclain egh steam boiler. The heating system is two pipe steam and each radiator has a steam trap. The boiler room has a combination of wet returns and dry return. The dry return connects with a float/trap above boiler with main steam vent. Its been a mystery how the radiators vent that are tied into the wet vent. Maybe another hidden float / trap.

recently the boiler would not heat the home and I noted the proper water level in glass. I wanted to confirm water level so I shut boiler and open drain valve. instead of releasing water the boiler sucked air for several minutes. finally the water drained and I checked level, low water cutoff and feeder.

since then the boiler has heated the home better than ever ? its been a week.

what happened? how do I prevent it again ? the boiler was installed three years ago.

Steamhead

Somehow the system created a vacuum. What vent is on that float trap?

joecorn

yes

a vacuum was created ?

the main steam vent is a Hoffman 3/4 inch. I checked it for blockage during my initial inspect.

when the boiler fired I heard it venting properly

Jamie Hall

Maybe a silly question — but exactly which model Hoffman vent? The number, please…

pecmsg

Was everything hot at that time?

EBEBRATT-Ed

You can buy a steam rated vacuum breaker to put on the boiler but I would suspect you have other issues