cast iron fin tube in steam systems

Mike Miller_2

Okay you steam heads, I could use a little help here, I am working on a boiler replacement on a two pipe system with hoffman 17c traps and cast iron fin tube radiators. Now some of these radiators have had air vents added to them over the years, and I thought that this was a no no. But then, I get this service call the other day, and here is this two pipe system, with no traps at all, and air vents at every radiator and all over the place in the basement on every condensate return line before they go into a wet return. System works fine, so I had to really think this one out, and as I see it these air vents on this two pipe system with the Hoffman 17c and the main line air vents won't really cause any problems as long as the trap is working correctly, but they are surplus to the cause once I rebuild all of these traps, which is part of my bid on this thing, Ii think they were put on here because a service tech couldn't see how to fix the trap and had seen an air vent replacement do wonders on a single pipe system. So here is my point, if any of you esteemed gentlemen, (and otherwise) have anything to add to my thought process, or see something I missed, I would be most grateful for the input, I do want to give these customers the best job I can, and my ego hates not having a system work right when I am done with it. Thanks, Mike in Denver  

Jamie Hall

I know just what you mean!

It's annoying to have a system which is supposed to work one way, working but set up more or less 'incorrectly'!  Been there...  The main line air vents you will need -- after all, the air has to get out of the pipes somewhere! -- but in a two pipe system, you should't need the vents on the radiators -- although, as you note, they won't hurt anything.  Just not elegant.  Suspect you're right on the service man gettng carried away...



You say there are no traps on the radiation?  Or is it that they aren't working?  Or does each radiator go to a wet return?

Mike Miller_2

whoops two different systems

Jamie, sorry, I can see I should have been a little clearer. The one system I am working on is a two pipe with the traps, what blew my mind and was the reason I began this thread was a service call I went on last week just as I was putting this job together which had no traps on a two pipe system, just air vents on the cast iron fin tube radiation, (which both systems have), in the system without the traps the fin tube was installed with a slant toward the condensate line, and each radiator has a wet return, where the system with the traps was installed level, and some of the condensate lines tie together before dropping into the wet return. Thanks for your input. Your questions helped me get a better picture of the whole thing Mike from Denver