Adding a Steam Radiator

[Fein]

I plan to install a new small radiator on a one pipe steam system. This is for a new small bath on the second floor of a 1920's house. I would like to run the new line about 15'-0" between joists before heading down through an interior wall and teeing into the 2" main in the basement. All of the existing lines run directly up from the basement to the radiators.

Q 1. Is there a requirement to keep the horizontal run in an exposed area (basement)?

Q 2. Other than maintaining slope, are there many pitfalls to running a new steam line on an existing system?

Thanks!

[hj]

How many do you want other than you CANNOT do it, and it will NOT work. Steam radiators, especially one pipe systems MUST be above the main. Steam rises and condensage falls, and it has to drain backwards to the boiler. In the basement, the steam might get to the radiator, but the radiator would fill with condensation and stay there. That is why you see "flat panel" ceiling radiators along the basement ceiling of old buildings with one pipe steam systems.

[Fein]

Hj- I'm Not sure I follow you. Existing radiators all have longish horizontal runs in the basement. I'm just thinking of putting it between first and second floor instead of basement. Everything proposed would be above the main and sloped back to it. Thanks.

[hj]

You said, "down through an interior wall". DOWN usually means down, and one pipe steam lines cannot go down. AH, now I see that you were starting at the radiator and going to the main. In that case as long as you maintain pitch and use a large enough pipe it should work. I say "should" because one pipe steam systems can be tempermental and can make you pull your hair out when they do not work even though everything says they should.

[frenchie]

From the little bit I've come to understand, I don't think it's likely to be as simple as you think.

Your horizontal run would actually move up & down as the system cycles; because the vertical run below it expands when the heat comes on... Not sure if that can change the pitch, leading to pings. I do know that every time I've seen it (and I've only seen it a few times), the system pings.


Changes to a steam systems are not DIY-level work. The guys who designed those, understood thing that are now lost art. It's like wooden boat building, the province of some very few fanatics...

That said, about the best knowledge base I know of for steam heat systems, is heatinghelp.com's Wall.

[Fein]

I'll try and find an old salt who is willing to take a look at it. Two plumbers I've talked to were very negative (read 'no thanks- how about a pump system') about touching the old pipes (without even looking at them). The pipes are in good condition and when I moved a radiator for another room a few feet they came apart fine. Thanks for the note of caution.

[frenchie]

Holohan (the host at heatinghelp) has a book about steam systems. Probably worth every penny. I've got his radiant heat book & his hydronics book, they were both excellent.

Posting at that forum might help you track down someone local, who can work on the system, or help you out. Steam heads are a pretty small group,