Two-pipe radiators with no steam trap

MGSteamAmateur

We are the owners of a 32-apartment complex in Sioux City, Iowa that is heated mostly by a 31-year-old Burnham boiler.  The boiler sends steam to four different buildings.  Some of the radiators are one-pipe with air vents, some are two-pipe with steam traps, and some have two pipes with nothing.  We cannot understand how these last ones work as the steam would just sail right through them and not condense.  Can anyone explain how these work?  Is there a steam trap on the return line somewhere?  We are planning to replace all of our steam traps before the upcoming winter and need to know what to do with these.  Thanks.

Tim_Hodgson

no steam traps

You are correct that without a trap the steam will just blow through. I can only think of three possibilities:  The steam is throttled at the radiator inlet, the steam traps are in the basement ceiling or the condensate piping is directed into a wet return in the basement.

Good Luck,

Tim 

MGSteamAmateur

Install traps?

Thanks for your reply.  There are valves on the inlets to the radiators but this seems like a rather crude method of controlling the steam.  Would there be any harm in installing individual steam traps on the radiators if one of the other methods you mention is in effect?

AlexR

orifice plate

The term you want to search for is "orifice plate".  It's a metal disc with a hole drilled in it to limit steam flow.  I believe it basically fits into a pipe on the inlet side of the radiator, so it may be hard to tell it's there without looking carefully.  Maybe someone else can point you at a picture.

Charlie from wmass

DO NOT ADD TRAPS

If you do not know what is controlling the steam adding traps is a bad idea. the returns may go back below the water line or they may just use the differential of a large supply and a small return with orifices to control the flow. the steam will condense with out a trap there, that is not what a trap does. a trap allows air to leave and closes when the steam is there so the steam does not back flow into other radiator return pipes.

Steamhead

Take some pictures

of the boiler area and at least one of each two-pipe radiator variant. Let's take a look at it. 

nicholas bonham-carter

steam inlet valves

usually the inlet valves were designed with an adjustable limiting pin, or screw so that once the valve was opened just enough to allow only that amount of steam which could be condensed, the screw was tightened, thus preventing the valve from being opened any further. these systems operate best with a few ounces of pressure [2-10 oz.].

while you are replacing the innards of any non-functioning traps, look at the main [not radiator] air vents, as you do not want to pay the gas company to squeeeeeeeeze the air out of constipated little openings so the steam can rise quickly. keep the pressure low, and the venting generous so that the air escapes at a back-pressure of 2 ounces, with a cut-out on the system at 10 ounces or as low as your far-flung layout will allow [requires a vaporstat, and a good low-pressure gauge {gaugestore.com 0-15 ouces}].

get some of the books from the shop here which will explain further the concept of "vapor systems". your system is really one of the best when properly maintained.--nbc

MGSteamAmateur

Many thanks

Thanks, all, for the responses.  I do have all of Dan's books and I see that he does discuss systems like what I have described.  I will post some pictures when I get a chance.

Jamie Hall

There is nothing crude

about controlling the steam flow to a radiator with an adjustable valve or an orifice at the inlet.  Quite the contrary.  If it is done right, and some idiot doesn't mess with the pressure of the system (keep it low!!!), you get a system which supplies exactly enough steam to meet the needs of the radiator with no moving parts; nothing to wear out, nothing to break.  Wonderful and elegant.  Likely enough they aren't broke, so don't go and try to fix them.



Now you do need to keep your pressure down, but that pretty well goes without saying.  10 ounces max., perhaps -- or as low, anyway, as your controls will let you and you get even heat (assuming that everything mechanical is right, that is).