Main Steam Relief Valve

Eric W. Bray

The valve shown here has been on my system for over (20)twenty years! (SEE ATTACHMENT)

How is it SUPPOSE to work?

Isn't it suppose to open when the steam first warms it up and close when it cools off?

Isn't it possible for it to fail in the open position and how do you test to see if it has failed in the open position?

Jamie Hall

eh?

Are you sure that's a steam vent? Could it be a main air vent, such as is used on vapour systems? In which case, it should be open (letting air out) until steam hits it, when it should close... I'd worry some if steam were coming out of it...

Good luck!

I am now going to retire the the Handbook's Companion to see if there might be a picture of it...

Jamie H

ed wallace

air vent

that is a main air vent its job is to vent air from the steam main so that steam can flow to the radiaters your heating contractor can replace it not sold at home depot

Eric W. Bray

Air vent Valve Problem

Thanks;

I replaced it with a NEW Hoffman No. 75H

All is well now.

Jacob Myron_2

Vent Valve

The green thing you have on theat pipe appears to be a Hoffman Vent valve.

The valves purpose is to vent air out of the steam main so steam can flow quicker to the radiators. The steam does not travel faster. Because large amounts of air were releasd in the basement that air does not travel to the radiators.

The radiator vents have much smaller orifices in them than the main vent in the basement, if you did not have the main vent in the basement it would take a longer period of time to vent the air out of the piping, this would result in a longer period of time for the steam to get to the radiator.

If your steam system operates at less than 5 PSIG and and the drop back is more than a pound use a Hoffman 75. They have a larger air release orifice than a Hofmann 75H.

The 75 H is for higher operating pressures than the 75.


Jake.