Subject: Re: Double-venting radiators in one-pipe steam system

From: Dave Nelsen <[email-masked]>
Date: 20 Oct 1995 01:38:17 GMT

if you are having problems with a slow radiator on a one pipe steam system 
it is most likley due to a bad main steam vent. these vents allow the 
steam to quickley travel down the main then rise up to the radiators. the 
problem with double venting the radiator is when a lot of steam enters a 
cold radiator it will condence forming a vaccume and draw air back into 
the radiator until it equilizes. if you still have aproblem after 
replacing the main vents you can try venting the riser leading to the 
radiator this will get the steam to the radiator quickly then a normal 
vent can be used on the radiator itself.

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From: [email-masked] (burdickw)
Date: 20 Oct 1995 22:27:43 GMT

MUR ([email-masked]) wrote: : A heating mechanic suggested
installing a second air vent in a one-pipe : steam radiator that takes too
long to heat up. This suggestion was made : after all of the usual
remedies were tried, and didn't work - the one vent : on the slow radiator
was set to the maximum, the other radiators in the bldg. : were set to the
minimum, the vent itself was checked, the pitch and the : sizing of the
piping seemed OK. : Have any of you double vented a one-pipe steam
radiator? Will adding : a second vent to a radiator decrease the
resistance to the cold air : escaping enough to make a difference? 

Double vents are a standard solution used in one-pipe steam systems where
one radiator won't heat quickly enough.  I've seen it done; I've also seen it
recommended in old textbooks.  It's a better idea than cutting back the
venting rate on all the other radiators! 

Have you checked the quickvent on the main serving this radiator?  If 
that is blocked, it can cause this problem.  Also, sometimes there isn't 
a quickvent installed close enough to the radiator.  The radiator vent 
can't be expected to vent the main as well as the radiator and riser, 
it's not big enough.

Speaking of which, another solution to your problem is to install a
quickvent of the type used at the ends of the mains on, or very near, the
slow radiator. 

Hope this is helpful!

				--Bill Burdick