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Adding Steam Heat to a New Attached Garage 2nd Floor.

AdmiralYoda Member Posts: 553
edited December 2021 in Strictly Steam
We are thinking of putting a 2 car garage onto our house that will attach to the kitchen. There will be a staircase connected to the end of the kitchen that goes up to the 2nd floor of this garage that will be finished.

Thinking tight construction, great insulation, great windows, etc. Overall that living space will be roughly 750 sq. ft. Rough heatloss calculation is about 12,500 btu/h or 51ish EDR.

I'm toying with the idea of adding steam heat there. My boiler is oversized by about 100 EDR or so and should handle the extra work.

The main concerns are:
1. I would have to install a runout to this living space which may be difficult. The walls will be open, but still. I'm not sure if the main it would be attached to can even supply that much steam.
2. In this new living space the furthest radiator will be something like 60-70 feet of pipe away from the main. That's probably 100ft or so from the boiler. Maybe even a little more.
3. New radiators aren't cheap. Expert steam pipe fitters aren't cheap, and neither are the fittings and pipes.

I'm toying with the idea of adding a different heat source for this area.
1. Hot water baseboard fed from the boiler.
2. Hot water baseboard from a hot water heater installed in the new living space.
3. Electric oil-filled baseboard.

What do you pro's think....stick with steam or pick something else. I'm just in the idea phase now...just want to educate myself a bit on available options before I move forward. Thanks!


    EBEBRATT-Ed Member Posts: 13,422
    Electric baseboard.

    Not likely you can go that far with steam. You would have to add a condensate pump to get the condensate back and you would have a balancing nightmare. I doubt you would be satisfied with it.Adding zone valves to the eteam system will open up all kinds of problems

    Hot water with a loop off the boiler is a possibility, you would need about 22 ft of baseboard.
    copper tubing or pex pipe and fittings
    a heat exchanger
    expansion tank
    prv water feeder
    relief valve
    two circulatores
    pipe insulation
    and glycol if you don't heat it all the time

    A lot of $$$$ for 12,000 btus

    Electric heat is some baseboard wiring thermostats and circuit breaker

    For 12000 btu you would need 15' of baseboard about 3500 watts.

    You might get away with 1 20 amp 240 volt circuit
  • Jamie Hall
    Jamie Hall Member Posts: 21,088
    Much as I like steam... I think I would use baseboard hot water coming off the boiler -- either through a tankless coil in the boiler if it has one, or through a heat exchanger. Why a heat exchanger? Because purging and keeping purged that much line and going up to the second floor would be... shall we say difficult? You'd need a couple of pumps (one to circulate boiler water, one to circulate up to your baseboard) and an aquastat to make sure the boiler water was at least warm if not hot. You can use PEX, which will make the job easier.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 7,708
    I would use a panel radiator, either electric or hot water to get the radiant heat you won't get from baseboard.
  • AdmiralYoda
    AdmiralYoda Member Posts: 553
    edited December 2021
    Thank you @EBEBRATT-Ed and @Jamie Hall

    What I had thought....that's alot of $$$ for 12k btus. I'm fine with the simplicity of electric oil filled baseboards....I just hate electricity.

    My boiler doesn't have a coil and it sounds rather complicated ($$) to even tap off of the boiler.
  • bburd
    bburd Member Posts: 646
    edited December 2021
    I would take a hard look at my electric rates before making that choice. If it were my house I would probably go with hot water baseboard off the boiler as a separate zone.

    Home additions almost never have the same heating requirements as the original space, and nearly always are more comfortable on their own zone.

  • AdmiralYoda
    AdmiralYoda Member Posts: 553
    @mattmia2 Interesting, I didn't know those existed. Any favorite brands of electric panel radiators?

    My other main option is adding an electric water heater for hot water baseboards but with that comes some risks as well. If I'm going to go electric a panel radiator might not be a bad idea.
  • Mosherd1
    Mosherd1 Member Posts: 48
    What’s the space going to be used for?  The thing with bonus rooms over heated garages is the floors are always cold, radiant floors are perfect for these rooms but come at a cost. Electric baseboard is going to be the least expensive to install, typically most expensive to operate. Would a/c be beneficial, you could go with a mini split heat pump, but your still going to have cold floors. 
  • AdmiralYoda
    AdmiralYoda Member Posts: 553
    @Mosherd1 First let me just say I'm just a homeowner and a steam enthusiast, so I'm a little behind on the latest HVAC gizmo's.

    This space *should* be used regularly, both as an office which will also be a spare bedroom and as a gym/lounge area. I'm definitely thinking of a programmable thermostat for up there to limit heating when we aren't typically going to be using it.

    I do plan on some sort of AC for this space. Not exactly central air, as the main house isn't equipped for it and we get by with good window air conditioners. A mini-split did come to mind for this as I'd prefer not to install duct work and an air handler.

    The floors will have a very high R value in them. Not sure if it is going to be spray foam, mineral wool or fiberglass but whatever will fit in a 12" joist.
  • Steamhead
    Steamhead Member Posts: 15,983
    How close does the existing steam main come to where the radiator runout would tie in?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • mattmia2
    mattmia2 Member Posts: 7,708

    @mattmia2 Interesting, I didn't know those existed. Any favorite brands of electric panel radiators?

    My other main option is adding an electric water heater for hot water baseboards but with that comes some risks as well. If I'm going to go electric a panel radiator might not be a bad idea.

    I just know they exist, i don't have any experience. I know the room i have heated with a Runtal hot water radiator is the most comfortable room in my house and they do make electric versions but there might be more cost effective options.

    If you were to buy the pieces you need to make a hot water heater in to a makeshift boiler, you might as well use those pieces to add a hot water loop to the boiler.

    Some electric radiant on the floor just to take the chill off might be a good addition too.
  • AdmiralYoda
    AdmiralYoda Member Posts: 553
    @Steamhead Don't have formal plans to give an exact answer yet, but my best educated guess would be 50-60ft from the main to where the radiator would be.
  • dabrakeman
    dabrakeman Member Posts: 386
    @Steamhead, were you thinking of treating the end of the runout in the garage as the end of main or at least with the highest system venting at the end of that runout?