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One-Pipe Steam --> Radiant Underfloor??

DennisR Member Posts: 2
I could use some advice from the pros!

I own an 1890's Victorian. I believe the heat is steam, since the radiators are single-piped, have air valves, and look a lot like the picture here: http://upload.wikimedia.org/wikipedia/commons/f/f1/2006_400x700_one_pipe_steam_radiator.jpg

I'm remodelling a (small!) bathroom, and it would be really nice if I could remove the radiator. I was hoping I could use the existing pipe, attach copper piping, run it under the (brand new by yours truly) subfloor, and attach radiating plates to do underfloor heating.

Is this even possible with a system like mine? Any experience, advice, or "Don't be an idiot" replies would be most helpful!



  • Al Letellier_9
    Al Letellier_9 Member Posts: 929
    radiant with steam

    What you suggest just won't work. You have to let the air out to let the steam in and then need enough room to get the condensate back to the boiler. You will need to add some sort of heat exchanger to the boiler and add in the necessary hardware to do a radiant job in the bathroom. You might want to consider an electric mat for the bathroom floor to keep it warm but it may not be enough to heat the room. This is not a DIY project unless you have some experience with this trade or get some professional advise and coaching. It think this is one project that needs to be budgeted in for a pro to do.

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  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    If the radiator is \"in the way\"

    have it replaced with another cast-iron radiator that is shaped differently, but has the same heating capacity. Yes, you can still get them!

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  • DennisR
    DennisR Member Posts: 2

    What if I whine, throw a fit, stomp on the floor, and bang my spoon on the table ... THEN is there a way to do it? ;-)

    Thank you for the advice, gentlemen. At least for the time being, the radiator goes back in.

    Please correct me if I'm wrong, but as I consider longer-term possibilities, to put heat under the joists on the ground floor means:
    a) Grab the condensate on its way back to the boiler and pumping it through the radiant system before returning it, or
    b) Using a heat exchanger to get hot water using the existing boiler, or
    c) Build a new system for the ground floor.

    Related question: how pricey are energy-efficient natural gas steam boilers, if you're heating a poorly insulated house of about 2000 sq ft (plus surprisingly usable basement) near Chicago? The existing boiler is in good repair, but is anything but recent. I shudder to think how efficient it is.

    Thanks Again,
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    The best gas-fired steam boiler

    is a wet-base design, as used for oil, with a power gas burner in it. This is pretty common on commercial boilers but not so much on residential ones. We would not normally "field-engineer" such a thing for liability reasons, but one or two manufacturers offer this as a factory option. We're putting one in right now, a Smith G-8, six-section. Smith offers the 8 series, normally oil-fired, with a Carlin EZ-Gas burner as the G-8.

    The wet-base boiler almost completely surrounds the flame with water-backed cast iron. Conversely, the usual atmospheric gas boiler has the flames completely below the cast-iron block. So the latter type loses quite a bit of heat from the base. Now you know why this type of boiler cannot be installed on combustible floors.

    Interestingly enough, DOE doesn't see this as a problem, but it stands to reason that any heat that gets out of the firing zone and doesn't help produce steam is wasted.

    The wet-base design also allows you to switch fuels without buying a new boiler. You simply have a pro change the burner and a couple other things, and tune it with a digital analyzer.

    Price-wise? It's a bit higher than the usual atmospheric, but you get what you pay for.

    Watch for pics here on the Wall when we get our G-8 up and running.

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