Adding a radiator

Jordan

I have a one-pipe steam system in an 80-year old house with original cast-iron radiators. I am contemplating finishing an unfinished, radiator-less room in my attic. I want to put a new cast-iron radiator in this room and, as near as I can tell, I have two options: 1) extend a pipe up from the second-floor bathroom radiator below, which would put the new radiator under the one window in the attic room; and 2) put a pipe through the wall opposite the window and connect with the radiator in the adjoining attic room (this radiator is next to the wall in a corner with an exterior wall). This second option would put the new radiator near the corner of the room to be finished, where the roof slopes downward toward the side of the house.

I read in your "Old radiator Q & A" from 1999 that "ideally a cast-iron radiator should be under the window," but my architect tells me that the "through the wall" option will provide as much heat while working out better cost-wise and design-wise.

Which option would you recommend? Or do you have another to suggest?

By the way, I recently read "The Lost Art of Steam Heating" and enjoyed it so much that I ordered copies for two of my neighbors, who are architects, and just today ordered "We've Got Heat: the Homeowner's Guide...". Thanks for sharing your treasure-trove of knowledge on a fascinating subject.

Sincerely,

Jordan of Richmond Hill

Steamhead

Whichever way you go

be aware that you may need to "drip" the base of the riser into the return. The reason is that a horizontal pipe can handle more steam when it is dripped. The drip will keep excess condensate out of the runout between the steam main and the radiator riser.

I'd run the pipe for the new radiator off the bathroom radiator riser since a vertical pipe can carry more steam than a horizontal one.

Check the sizing tables in Lost Art to be sure your pipes will handle the load.

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