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Stay with one pipe ?

M Downey_2
M Downey_2 Member Posts: 21
My sister and brother in law, who have a one-pipe steam system are looking to possibly swap out their old boiler (approx. 30 yrs old).  I have concerns with the integrity of the piping, due to the age of the house (circa 1924). I was just wondering if I would be better off  removing the old piping and installing a hot water radiant system.  Obviously the allure of running pex is more appealing to me than replacing all the old steam piping (finished drywall ceiling in the basement,etc).  From an energy standpoint wouldn't a hot water system be more efficient ? As this would be a "no-pay" for me I would obviously like them to obtain a "Cadillac" system. Home is approximately 1800 sq ft, two stories, with newly finished basement (not heated, yet) and they do utilize a room in the attic. Any comments or input would be greatly appreciated,


  • Jamie Hall
    Jamie Hall Member Posts: 17,060
    I'd stay

    with it.  One pipe steam is a very very good system -- easy to maintain and very good even heat.  I would not be too concerned about the steam pipes.  Mine are over a century old now, and the only one which has given any problem at all is a wet return which was unused for some years.  Everything else is completely sound.  Steam pipes and radiators do rust, but only very very slowly.  Do NOT, however, attempt to pressure test the system.  It wasn't designed or built for pressures over a pound or two!

    Even if you were to run the pex yourself, going to hot water will not be a zero cost option.  There may be a very small increase in efficiency for a hot water system -- if, and only if, you are using a very high efficiency mod-con boiler with all the bells and whistles.  Otherwise, no.  The increase is minor (at best, for a system using 1,000 gallons of oil a year, you might save as much as 87 gallons if you were really fortunate), and you will never pay back the cost to run the pex.  Nor, in my humble opinion, will you get more comfort, once you get the steam system running properly (it's likely that it needs tuning -- you do have Dan's books, don't you?).  A good steam system is the Cadillac of systems!

    While replacing the boiler, you can probably figure out a way to pick up a new radiator (steam) in the attic without too much trouble.  Ideally, obviously, the new riser would be iron or steel.  However, in a pinch and if you don't mind the odd expansion noise, you can use copper.  Just make sure that it is free to expand, and that it can expand in such a way as to not twist any joints if at all possible.  The basement, if it needs heat, can be heated with a hot water loop off the steam boiler.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • M Downey_2
    M Downey_2 Member Posts: 21
    Thanks Jamie

    Thanks for your input, Jamie, I appreciate it !  Yes, I do own most of Dan's books, but I'll be adding to the library with this job, because I'm going to pick up "Every Darn Radiator".  After I do a heat load,  I want to  make sure that the load matches the boiler (my brother-in-law  might have taken out a radiator years ago). And yes, being a pipefitter by trade I'll be putting in the riser with steel pipe and cast fittings. Having concentrated on the refrigeration end of the industry the last 10 yrs, I've been out of the loop as far as boilers go, do you have a preference as far as boilers go ? Do they make a high efficiency steamer ?
  • Steamhead
    Steamhead Member Posts: 14,838
    edited October 2009
    Not in the 90%+ range

    yet, though it is possible to do so.

    If you're burning oil, the Burnham MegaSteam is the best. Unfortunately they haven't approved it with a gas burner (yet?). For gas, I'd use a Slant/Fin Intrepid or Smith G-8 boiler- these are wet-base units primarily marketed as oil-fired, but are certified for use with power gas burners. These units have roughly 6-7% better thermal efficiency than the usual atmospheric gas boiler.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
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