Unknown 2 pipe steam radiator inlet part

euge

The attached images show the inlet and outlet piping used for all the radiators in a single home two pipe steam system. The system was likely downsized from its original full house application, retaining a kitchen and all bathroom radiators. The house was built in 1938 in Westchester County NY.

Guess which piping is used for the inlet? It’s NOT the two 90 degree elbows.

Before I wrenched these pipes apart I thought that the straight L shaped part would be some sort of steam trap, but all the radiators are piped so that this is the inlet piping for all of them.

Is this some sort of old fashioned inlet device? Or is it actually a small orifice steam trap that the previous inhabitants decided worked better in reverse and reversed ALL the radiators to function backwards?

I haven’t yet found anything on the internet that looks like this so I’m really not sure what kind of part this is supposed to be.

Any ideas?

Steamhead

What other devices are in that system- examples might be a return trap or vent trap?

euge

From what I can tell, that’s it. The return mains have air vents down in the basement. Doesn’t seem like steam traps are used on the radiators, just seems to be these open elbows going to the return lines.

It doesn’t make sense from what I’ve read about these systems, including Dan Holohan’s articles and one of his books. There is heat coming from the system at least, but the configuration doesn’t match anything I’ve seen in references.

My guess is that the inlet should be the outlet and the outlet the inlet. I think that the small orifice easily got clogged, and flipping all the radiators around let there be some heat even though that really doesn’t seem ideal. But if that is the case, putting them back in their original directions might not be a good long term plan.

That L part has stamped on it “TYPE NO 197A” but I couldn’t find a manufacturer name.

Steamhead

OK- those inlet fittings are probably there to orifice the incoming steam so it doesn't reach the dry return as long as the pressure doesn't get too high.

euge

Ok, so this is a two-pipe system, orificed on the inlet but with no steam trap at the outlet? This is a “valid” configuration?

Steam pressure is no higher than 2 psig at the boiler. The main vents aren’t high enough to allow more pressure in the system.

Would it be advisable though to plan to add steam traps at the outlet and remove the orifice at the inlet?

JStar

One big advantage of orifice systems is that you don't need radiator traps. The orifice is sized to only fill the radiator about 80%, so steam never enters the return, thus no need for traps.

These systems typically run at just a few ounces of pressure, not pounds. If this is set up right, you've got one of the best heating systems ever made.

JUGHNE

Was there any adjustment on the inlet device?
That nut on the bottom?
Seems like it may have been one size fits most application and was field adjusted for each emitter.