Cold two-pipe steam radiator

jjkraft

I have seven cast iron two-pipe steam radiators. All are hot except one. The intake pipe on the cold radiator is hot so I know steam is getting to that spot in the house. Also, when I shut all of the other radiators down (closing the steam valves), that radiator will heat up.

I've replaced the steam vent with no luck and tried adjusting the steam vents on the other radiators. Any thoughts on next steps?

Thanks.

Unknown

2 Pipe Steam

If you have a 2 pipe steam systems you generally don't need vents on your radiators. You should have a steam trap (like the one in the attached picture) on the pipe coming out of the bottom of each radiator. I've also attached a diagram of a typical 2 pipe steam system.

Do you have steam traps on your radiators? Why I'm asking is that while most 2 pipe systems have them, there is a type of two pipe system that doesn't. If youy have traps it sounds as though one or more of your traps is bad.  What is the maximum steam pressure your system attains?



You might want to get a couple of books on steam heating that are offered on this site. One is "We Got Steam Heat"

[url=http://www.heatinghelp.com/products/Books/5/61/We-Got-Steam-Heat-A-Homeowners-Guide-to-Peaceful-Coexistence]http://www.heatinghelp.com/products/Books/5/61/We-Got-Steam-Heat-A-Homeowners-Guide-to-Peaceful-Coexistence

and the other is "The Lost Art of Steam Heating" http://www.heatinghelp.com/products/Books/5/68/Lost-Art-Of-Steam-Heating

These books are easy reading, humorous and packed full of facts, pictures and diagrams about steam heating. They pay for themselves very quickly. - Rod

Jamie Hall

It does sound

like a bad trap, although failing open is more common than failing closed.  As Rod notes, very very few two pipe systems had radiator vents; their existence suggests that perhaps someone in years previous did some unwarranted "fixing".  If there is a bad trap, though, it would tend to keep that radiator from working, vent or no vent, as the feed line to a two pipe radiator is not meant to handle condensate and, although the steam would try to get in, the water would have trouble getting out.

BRIANJ

COLD RADIATOR

Not all two pipe systems have traps. Some have return els which allow the air and condensate to pass through. However, the els can sometimes become clogged and block the air from escaping and therefore steam from entering. Pretty easy to clean but be careful, the radiator might be filled with water. Ask me how I know? Good Luck.

jjkraft

No traps on the 2 pipe system

No traps as far as I can tell. I'm also not sure about the maximum steam pressure the system attains.



I've attached a photo of the cold radiator.



A local DIY guy said that I might need to take the radiator and de-gunk it. Could a build-up be causing the problems? The system is probably 30+ years old (in a house from 1910).

Jamie Hall

Looks very like

one of the many different systems which had a widget of some kind in the outlet elbow, which had a small orifice or other contraption to allow air out.  These can get clogged and not allow the air out -- presto, no heat.



The thing to do is to take the outlet elbow off -- carefully -- it has a union to the radiator spud so this isn't hard, with care, and examine the innards and clean everything up nicely.  Then put it back together; that should help.

TomM

yeah but

If that was some type of orifice on the return, even if it was clogged, the rad would still heat and act like a one pipe radiator because of the air vent.

TomM

valve?

are you sure that that old inlet valve is fully open?

jjkraft

Another photo

I've opened and closed the inlet valve several times. It's currently open. The vent is also fully open (and replaced once). Also, when all of the other radiators in the house are closed, this one will heat up.



Another photo from a different angle.



Thanks for all the help.

Unknown

Condensate needs to escape

Even with the air vent, it won't act like a one pipe steam system very long as the inlet pipe is too small and the condensate can't escape and will back up. As has been mentioned above by BrainJ and Jamie the elbow on the side away from the valve most probably is plugged and needs cleaning. Since condensate is being backed up in the radiator, be careful as you may have a lot of water leak out when you crack the fittings so be prepared for that.

You might also check the slope of the radiator. In most two pipe radiators this isn't a problem at steam is introduced at the top of the radiator but since your inlet and outlet are at the same level (the bottom of the radiator) you might want to make sure the radiator is either level or has a very slight slope towards the exit pipe.

- Rod

Steamhead

So does air

from the steam mains that is. This could be a main-venting issue. Measure the length and diameter of your steam mains and tell us what vents are installed at or near the ends, and we can tell you what you need.