testing a main vent

zepfan

what is the best way to tell if a main vent on a two pipe system is plugged up without burning yourself? just slowly unscrew it till you get steam and no air? i need to go look at a steam system on tuesday where the problem is several radiators on the top floor don't get hot and haven't for about ten years.i am suspecting a plugged main vent or too low of pressure.steam systems are very rare in our area.

gerry gill

turn off the system,

then unscrew the vent, and holding the vent vertical, blow up into it..if your cheeks puff out from backpressure she most likely is no good anymore..if you can easily blow thru it, then it is probably so other issue that is effecting your rads.

crash2009

Shut off the system

  Gerry explained stuck closed, I will attempt to explain stuck open.  Remove the vent.  Turn the vent upside down, keeping it verticle, blow into it.  If air will pass, this is stuck open.  If the vent fails either test, sell them a new one.  For a look at whats inside those vents click on this  http://www.gwgillplumbingandheating.com/webapp/GetPage?pid=610

Dave in QCA

More information needed

It might be best if you take pictures, make observations, then come back to the wall.

My first thoughts are that I have never seen nor heard of a steam main getting plugged up.   Also, raising the pressure setting is the sign of an attempt to fix a system that is not working, withouth correcting the actual problem.  Usually, the increased pressue causes more problems than it fixes.  DON"T raise the pressure.  Residential systems operate at 2 PSI max.   Most operate quite well at 0.5 psi.