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Gas Hot water boiler or furnace; utility separation

Bake Member Posts: 4
Hello.  I have a 2 flat building that is about 60 years old...maybe a little older.  Each unit has 2 bedrooms, 1 bathroom, living room, dining room and  enclosed back porch.  Each unit is about 800 sq. ft.  The basement is finished...as I use it to stay overnight from taking long drives home.  The building currently has a hot water gas boiler with the older cast iron radiators.  I am looking to separate the heat and place that responsibility on the tenant.  I have been told that I can keep the current boiler for the first floor and install either another gas hot water boiler or a gas furnace for the second floor. 

If I choose to install a furnace on the 2nd floor, the only place to set it is on the enclosed back porch...which is insulated.  The contractor would have to get through the brick separating the porch and run the duct work over head.  Can the return be placed on the enclosed back porch or any area that is about 10 x 12?  Or does the return have to be in an open area? The porch has a door and on the other side of the furnace is a bedroom with a door.

If I choose to install the boiler, the contractor stated that he can do most of his work from the basement.  Therefore not making holes in the walls for the duct work and vents....less clean up and patching time. He stated that he would run new copper pipes to the 2nd floor.

Can you tell me:

which system is the better solution? which system would be the least expensive to install? which system provides the better heat? which system is more efficient regarding monthly expense?  Please provide me with pros and cons.

I thank you in advance


  • Brad White
    Brad White Member Posts: 2,398
    A lot of things to consider

    Quite a few details I need to sort out. At the core, I think you are asking if a furnace (meaning an air system) would be better than a boiler (presumably a water system).

    All things being equal, I would go with a water (hydronic) system. You can move more BTUs through a 3/4" pipe than a 12x8 duct, for one thing. The downside is any piping subject to freezing. You did mention the porch after all.

    The furnace, no doubt will be less expensive but will take up more space but the larger issue is the return air paths. Sometimes these are not given the full consideration and this can create pressure differences, inducing outside air or affecting combustion air and flue gas exhaust. Sight unseen, I have to at least ask that you address this if you go that way. I also have to presume that your contractor will address combustion air, all of that good code stuff.

    The remaining challenge you have is finding a boiler or furnace small enough.

    So to recap:

    Hydronic/Hot Water heat usually gives superior comfort but often costs more to install. It also allows easier zoning, providing nearly individual room comfort for modest cost. Piping must be freeze protected if it is run anywhere there is a possibility. Glycol is one method but has to be maintained. A chore.

    Warm air heat (furnace), usually costs less but typically has a single zone (one thermostat). For a small place, this may not be a problem.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
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