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Existing Steam versus New Forced Air?

bird Member Posts: 2
I bought an 1836 two-course brick house, with plaster directly onto the brick, so no insulation in the walls.  The house is large (3168 sq. ft.) and came with a now eight-year-old gas one-pipe steam boiler.  I am told that it is oversized at 299k btu by about 50k btu.  There are 17 radiators.

I do not presently use almost half the house, and "experts" are telling me to have a 90k btu high-efficiency gas two-stage furnace installed to heat the downstairs and one bedroom and bath upstairs.  (That means lots of holes cut into old hardwood floors.)  Also, they don't want to heat the bathroom upstairs in the far end of the house (I do use this--the only shower).

They say--on paper--this furnace would cut my heating bills in half.  I am very suspicious.  Does anyone have any advice?


  • Jamie Hall
    Jamie Hall Member Posts: 22,942
    Oh dear...

    in my humble opinion, bad idea.  For several reasons.

    1.  You have a functioning steam system.  It may or may not be oversized.  Correct sizing is dependent on the number and size of the radiators, plus a "pickup" factor.  Did your experts determine the size based on that?  Or on what?  In any event a roughly 20% oversize is no big deal.

    2.  It is perfectly possible to turn radiators off with one pipe steam.  There are several ways to do it, perhaps the best being thermostatically controlled vents on the radiators (when the room is above the setting, the vent closes and the radiator doesn't get -- or use -- any steam).  If you went that route, you could turn them back up to warm the spaces in question when, and if, you needed to.

    3.  The modifications to the vents to "turn off" those rooms aren't going to cost all that much.

    4.  Your present boiler isn't, granted, as efficient as a new, properly installed, forced air furnace might be.  However, have you computed the payback on the installation cost of the forced air system?  I would be a little surprised if there was a payback at all -- that is, the savings in fuel may be less than the cost of the money used to install the forced air system.

    5.  If you take the boiler out, you will then have no way to heat the rooms without the forced air system if and when you want to without a new furnace (again) and lots of new duct work (again).  If you don't take the boiler out, why not go back to item 2. and use it?

    6.  It has been my experience that unheated rooms in an otherwise heated house suffer considerably from moisture damage (mold, mildew, damaged plaster, etc.).  In the long run, this can be very expensive.

    7.  As you note, installing the duct work is going to do a good deal of damage to the historic fabric of the house.

    I could think of more, but I'll stop there.

    And I do know about these things -- I am the building super for an historic house and museum.


    Don't do it.  Keep the steam, and tweak it and modify it to suit your needs.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Unknown
    edited February 2010
    Forced Air is a Mistake!

    Forget the Forced Air! I very much doubt if you would be happy with the result. Forced Air works by blowing air about and in old houses there are already enough drafts without creating more!  As for ruining those beautiful hardwood floors by chopping  holes in them that isn't the way to go either!

     There is probably a lot you can do to improve your steam system. For example- One of the things you can do is uses TRVs  I have a 3 story house (no insulation) in Maine and shut down about 70 % of it in the winter by using TRVs (Thermostatic Radiator Valves)  These attach to your radiators and are a type of thermostat for each room. The minimum setting is about 42 degrees F. which prevent the water piping and plaster from freezing yet can be turned up easily if want to use that room.

    I would suggest that you have a talk with a steam pro who is familiar with steam.  You might want to look in the :"Find a Professional" section at the top of this page. Scroll down to "States" (the zip code function has new software and has some "bugs") and see if there is a steam pro located near you. There are some really good guys listed there. Keep in mind that while there are a lot of people in the heating business, very few really understand steam so seek out a real steam pro. Let us know where you are located as someone may know a good steam pro near you that they can recommend.

    You might also want to get a book that has just been published "Greening Steam". It's available on this site.  Here 's a link to it:


    I just read it last week and it has a lot of good information on making your steam system more economical. (including info on TRVs)

    If you have questions there are a lot of helpful people on this site both homeowners and steam pros, who can help you.

    - Rod
  • Robbie
    Robbie Member Posts: 41

    Have you ever noticed how many old homes have steam systems, and the remains of a forced air system? My 1883 Victorian has single pipe steam, but has the old ducts for forced air heat in the walls still... And I looked at one 1904 one with the forced air still in place. Looks like the steam predated the electricity in the house- one of the ducts has wiring run through it- Knob and Tube! So, apparently by the time they converted to electricity from gas, they'd had steam for a while!

  • Polycarp
    Polycarp Member Posts: 135
    Gravity Heat

    I have one of these houses.  However, they had gravity air and not forced air heating:  heated air, but no fan.  Forced air heating was not introduced until the mid-1930s.

    Gravity air is basically a less effective version of forced air.  It has most of the disadvantages and not all of the advantages.
  • RAF
    RAF Member Posts: 65
    There not air ducts

    That was the central intercom system of the day:-)
  • Robbie
    Robbie Member Posts: 41
    edited February 2010
    Funny you should mention that...

    I used them to trace some of my outlets when I was in the basement the other day: Had a radio upstairs, plugged into the outlet I needed to trace, and positioned it near an opened duct outlet... Had the radio cranked, and went to the basement, and started flipping breakers till the radio went out- the sound was carried through the vent :) Worked well!

    I am considering using the duct to route micro-vent for A/C to the 2nd floor, and have some sort of plenum outlet at the end of each, so I can use the old grates, and have it look like an old air outlet. Have to find about a dozen or so grates, but seems like a simple way to run central air!

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