How do I know my main vent is working

DeeJay3

I've got a single-pipe steam system in a 3,000 sf house in CT. Boiler is new--installed 5 years ago.



The system has worked very very well since the install, but this year I'm experiencing a lot of hissing and some spitting from the rads.



I went to see if the main vent was in good shape and I can't tell if it is working; with the system on, I couldn't hear / feel any pressure coming from the main vent.



Any easy ways to test the main vent?

Jamie Hall

It is oddly difficult

to tell if a vent is actually venting -- you'd think it would be easy, but it's not.



What you can try, though, is a strip of tissue paper -- bathroom tissue is fine.  Hold it at one end with the other end right near the vent opening.  When the system starts to make steam, it should at least wiggle.  If not, chances are you are right -- the vent isn't opening, or not opening enough.



Sometimes you can clean them -- I've heard vinegar works well enough.  Sometimes you can't.