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  1. #1
    Join Date
    Apr 2012
    Posts
    28

    Arrow best furnace for demanding heating needs

    A family member has developed health problems including anemia and thyroid problems that cause them to feel cold all the time.

    As a result we have to keep the heat at between 78 to 80°. When this first started a couple years ago the furnace heat exchanger cracked within six months of turning the heat to this level.

    This was on a 90,000 btu 80% natural gas furnace. After that happened we got a 95% efficiency natural gas furnace and about a year after running it we have noticed problems with it.

    Is there a type of furnace that is designed to withstand these demanding heating needs without breaking? Our home is 1700 ft. Two stories.

  2. #2
    Join Date
    Aug 2010
    Location
    West Monroe, LA
    Posts
    1,537
    1st off a load needs to be preformed on the home by contractor. At that time you can tell him your needs for the temp. For both winter and summer and he can make recommendations. Also I would want the duct work reviewed over.

    It sounds like duct system might not be sized for the btus you need to keep the home comfortable with your existing furnace. This can lead to problems with high limit kicking out and heat exchanger failure. You might be surprised that with a smaller furnace you can keep the home at temps needed but with little more run time.

    The load cal. Will tell your contractor what is needed for your home to maintain those temps. Might even consider a modulating furnace for the home due to family health concerns. This will let the furnace control the temps better. You don't want to keep going through furnaces because of duct work being to
    Small. Also more info. On your home would be helpful.

  3. #3
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Most furances are oversized to begin with. Depending on where you live, maintaining 78F vs. 70F only requires a furance that's 10% larger. You'll have no issues with a "normally" sized furnace up until the 5 of 6 coldest days and only for 3-4 hours on those coldest days.

    Do you have a humidifier? At 78F I'm sweating and need to wear shorts and a T-shirt above 40%RH. IF you can keep it above 30%RH at 78-80F, rather than possibly 10-20% that you may see without a humidifier, you should see a big difference.

  4. #4
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,789
    As above, your furnace is probably over sized(did they put in the same sized furnace as the old one was), and a correctly size one would work much better for how you want to use it. A humidifier would probably help a lot also.
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  5. #5
    Join Date
    Apr 2012
    Posts
    28
    The new furnace is not 90,000 BTUs I believe it is somewhere around 40,000 BTUs.

    I wonder if I would be better off getting some sort of commercial/industrial furnace? Commercial buildings are usually made of large amounts of glass and so they would have high heating needs. The rock 'n roll Hall of Fame in Cleveland Ohio comes to mind.

    I would like to get away from combustion furnaces if it all possible, because of a problem I'm having with the combustion fumes from my furnace. I live in the Northeast part of the US near the Canadian border and so residential heat pumps are out of the question I believe.

    However I have a friend who works at a library and they recently had a new building built. They described the heating system as a roof mounted unit and from the way they described it almost sounded like a large heat pump.

    What type of commercial/industrial heating systems are available and would any be suited to my use?

  6. #6
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,789
    The library is probably using a gas RTU to heat with.

    Commercial building have a large heat loss load. but they generally don't heat the building to 78 degrees.

    Low air flow for the temp you want to maintain is probably the main cause of your short lived heat exchangers.

    For a 40,000 BTU input 95% efficient furnace to maintain a 78 or higher indoor temp, you would want it to move close to 900 CFM.
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  7. #7
    Join Date
    Apr 2012
    Posts
    28
    my furnace is a three stage how would I find out how many CFM's it's blowing? The fan speed seems to vary depending on how cold it is outside. Is it possible to get satisfactory heating with a heat pump in my climate? I've read new heat pumps have special antifreeze protection. The unit at the library may be a RTU but when the building was in construction stage the contractor also offered a heat pump as one of the options

  8. #8
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,789
    They don't make a 3 stage 40,000 BTU furnace. So if its 3 stages, its bigger then 40,000. How much air its moving can be measured.

    If your furnace is an up flow, the top panel is the burn panel, and the model number is in that compartment. You may want to look what model you have and post it.

    A 90,000 BTU 80 furnace outputs 72,000 BTUs, if they installed a 80,000 BTU 95% furnace, it outputs 76,000 BTUs. So knowing what furnace they installed for sure helps.

    Heat pumps work in most areas. What area are you in. Heat pumps aren't real efficient at keeping homes at 80.
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  9. #9
    Join Date
    Apr 2012
    Posts
    28
    im in rochester ny

  10. #10
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,789
    You would be using the aux heat a fair amount of the time. Depends on your electric and gas rate if its economical or not. But since you want to keep the temp high, I would think a heat pump would cost a lot more to use then a natural gas furnace.
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