Unwanted Vacum

Tom_42

How might I tell if my one-pipe steam system is producing unwanted vacuum. Lately after the system has stopped producing steam, within 10 minutes I hear this great sucking sound coming from usually just one of the radiator vents. To me this sounds like a vacum situation that is finally being releived. Can this be ok?

Ted_4

Vacuum

After a steam boiler has stopped producing steam, the steam left in the piping and radiators condenses and leaves....a vacuum! Normally all radiator vents would open and let in air to replace the steam, and the noise would be minimal.

The fact that one of your vents is producing a large amount of noise might indicate that other radiator vents or main vents (at the end of the steam main) are not functioning properly. Also, check to make sure all radiator valves are in the full-open position so that condensate and air can get out into the risers and mains.

Tom_42

Vents

The main vents are new. One is a Hoffman #75 the other a Dole #5 (I think). Anyway after this gushing in of AIR happens sometimes you will hear the main vents opening up. It sounds like a clink. The radiator vents are all VariValve vents that were installed last year. I would hate to have to replace them again this year.

Tom_42

Oversided Boiler

Could part of this problem also be too much pressure by an oversized boiler. I do have the pressuretrol to cut out at about 1.5 PSI with a cut in of 0.5 PSI. Sometimes it does cut out other times it does not. Also, it happens only on one of my two steam lines.

Dale

Pitch or junk

Sounds like since it's only on one line that you have poorly pitched main or that there's junk blocking something, I guess I would also take out take out the main vent on that line and see if it is really open and maybe leave it open from the pipe at the end of the call to see if when air gets in the inhalation noise stops.