Rearranging single pipe steam radiators

Phil_17

We bought an old house with single pipe steam last fall. I bought Dan's books last year and have been learning ever since. The house is large, with a main body and an attached ell in the rear. The main house has new windows and recent icynene insulation, while the back is in original condition. Needless to say the upgraded portion is comfortable, but the back can be downright cold.

I am thinking of swapping radiators around - trading large ones from the warm section with small ones in the colder area. From my reading I believe that the sizing of the pipes is based upon the run and not the size of the attached load (pressure drop is mostly a function of diameter and length, right?), so I think it should be okay for me to juggle them around, but wanted to be sure before I undertake that much work. I know I have other work to do with venting, as the cold end does not have adequate insulation on the pipes in the crawl space (main house is well insulated) and the cold rooms take a lot longer to get any heat than the warm ones.

From my reading it would appear that the boiler (~1950) is also not properly plumbed (no hartford loop, no equalizer, and the two risers are not connected via a common header) but that will have to wait until it gets replaced at some point in the future...

Any advice would be appreciated.

Tim Gardner

The sizing of the pipes is based on the attached load and on the run. Basically you have to have enough room for enough steam to get past the returning condensate. A big radiator needs a bigger pipe, and a long horizontal run needs to be bigger. Dan's book TLAOSH has the information needed to size the pipes.

You might be better off starting with the venting.

mel rowe

Does the back of the house, that you mentioned is cold, have any insulation in the walls? Also, how about the windows, and overhead? No matter what actions you take to increase heat to the area, I've found improved insulation to be a good starting point, with continuing payback in your heating efficiency. I have icynene in the attic, and a different type foam in the walls (non-expanding type). Other people like cellulose blown into the wall area. This might preclude the need to add more radiation to the area. It sounds like you have piping issues that need to be addressed as a higher priority than the radiator size issue.FWIW

headerless

I agree with Tim. Start with venting especially if the radiators in the cold rooms are cold. He is also right on the risers -- be careful with the 1" risers as they will never heat up big radiators -- see Dan's book or Hoffman's guide on steam heating.

I also started out w/ boiler where each riser went to seperate mains via it's own header. Must have been a common practice.

chuck_6

Phil:

You have to be careful moving radiators around as 1" pipe holds a lot less than 1 1/4" pipe (28 EDR vs 62 EDR). Make sure the main(s) are properly vented. If the original part of the house is on a different main, you may want to vent it faster, and the radiators as well. I would only use Gorton radiator and main vents. Get some insulation on the pipes and in the wall - blown in cellulose should help.

Chuck