Vacuum on steam radiators

TeeJay

We have a situation where the radiators are not getting hot. The 2" supply is hot but where it taps off to the bedroom is slightly warm. We opened up the radiator and feel it pulling a vacuum.  Can this be a partial blockage.

Jamie Hall

Look for a sag

or some other place where water can accumulate in the riser or runout...  that'll do it.

nicholas bonham-carter

radiator sucking air

in addition, if your main vent is plugged up, the radiator vents will be the only vacuum relief available to the system. that could be also the reason those radiators are not heating fully. if the steam arrives just after the thermostat is satisfied, they miss the boat.--nbc

DanCanDo

TeeJay's Co_Worker

This place is a huge apartment complex, system piping easily 70 years or older. (2) LARGE Weil McLain Boilers both with 10" Steam headers.  Piping is all jacked up.  The 2" pipe goes directly back to the condensate return, yet is set up as a One Pipe System.  2x3/4 Tee off top of pipe "should" be the steam supply, yet leads to the radiator trap.  The supply side come off the same 2" pipe, Tee on it's side, goes through a"float/ thermostatic" trap and up to the top of the radiator.  YES, this really is how it's piped.

I followed this pipe all the way back to the boiler room; I seen NO connection to "any" steam supply pipe.  The maintenance company has only been there for the past three years and the problem has been there that long...no records on file either.  Has numerous supply terminations that are flanged off.

Dan Houlihan...are you there??!!

Jamie Hall

Aren't you guys...

going to have fun.  Why do I have this feeling that that vacuum radiator may not be the only thing which is a little peculiar, to say the least?



If you two aren't really familiar with steam, or happy with it, you might want to contact one of the top men on this board -- depending on where you are -- to come around and give a third viewpoint, if only for laughs.

DanCanDo

Jamie...I hear ya

Jamie, I'm pretty familiar with steam...I tried to walk away, I really did, but I'm told I'm the only one making any kind of sense.  Hoping to hear back from the CZAR Daniel Houlihan.  Location is in Philadelphia, I have a call out to some local vendors looking for a "Senior Citizen" type former tradesman..."just in case" i'm missing something.  The place trully is a MESS though, but I like challenges.

nicholas bonham-carter

apartment complex

maybe you can draw a diagram of this layout. if the piping is 70 years old, it would have been done by the dead men, and probably worked well when first installed.

maybe it is an old vapor/ vacuum system, and the vacuum was serving a purpose in the days of coal. if so every component would have been designed for low pressure, such as 12 ounces.

are both boilers firing at the same time, or are they staged? are there motorised valves involved?--nbc

DanCanDo

NBC...

I'll visit again to post some good digiatls and do my best to provide a sketch.  There are not motorized dampers, boilers seem to be fired together.  I still can't see how steam gets into this "uninsulated", condensate return, is all it's proving to be. 

nicholas bonham-carter

staged firing

when you get this problem worked out, you may be able to make some additional improvement by way of a staged firing of the boilers. as pressure builds, the lead boiler continues, and the secondary goes off. when it is 20 below, and the condensing load is equal to the firing rate, they would both work.--nbc