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  1. #1
    Join Date
    Jun 2005
    Location
    New England
    Posts
    906
    I think the heat-exchanger on my 45 yr old Forced Hot Air furnace is beginning to go - we've had two CO alarms in the last month. I live in New England and am going to replace it.

    1) the guy who i want to have do the work likes American Standard - should I? If not, what are the good brands?

    2) Current furnace is 140KBTU in, 80% efficient. Maintains temperature fine, but can take about 1-2 hrs per degree to raise temp. Should i get something a little bigger?

    3) I'm offered 85% or 90% efficient models (latter is a few hundred more) - I assume I should go for the 90%. I value reliability, so I don't think I want to bother paying up for a few extra percent.

    4) My drum humidifier works fine (it's on the return), I maintain it. It is 18 yrs old though. Should I replace it (has the technology improved?) or re-use it?

    5) I don't -have- to go direct-vent, but I would assume I want to (or don't I have to with a 90% efficient furnace?)

    6) By the way - my old system was a coleman "high-velocity' system with 4" ducts. I assume if i get an oversized (or A/C-sized) fan I should be ok. (I have a separate A/C system in the attic)

    THANKS SO MUCH -
    /j

    [Edited by jeffw_00 on 01-03-2006 at 10:23 AM]

  2. #2
    Join Date
    Oct 2004
    Posts
    3,400
    Never oversize equipment.

    Your installer/servicer has good reasons for preferring a certain brand.

    That is the brand he is most familiar with. Go with whatever he recommends.

  3. #3
    Join Date
    Jun 2005
    Location
    New England
    Posts
    906
    Thanks - I think you're implying that these are pretty much commodities, and (like a lot of AC systems), the reliability depends more on the installer and less on the brand?

  4. #4
    Join Date
    Oct 2004
    Posts
    3,400
    Originally posted by jeffw_00
    Thanks - I think you're implying that these are pretty much commodities, and (like a lot of AC systems), the reliability depends more on the installer and less on the brand?
    Not implying.

    Vehemently stating!

  5. #5
    Join Date
    Jun 2005
    Location
    New England
    Posts
    906
    thanks 8-}

    any help on my other questions?
    /j

  6. #6
    Join Date
    Dec 2005
    Location
    Cleveland, OH
    Posts
    2,310
    If your furnace is 45 years old, I highly doubt it's anywhere near 80% efficient. More like 60-65%. Never mind what the bonnet is rated at, you'll never get that out of those old clunkers. Let your installing contractor select the proper size.

    I would replace the humidifier, the new ones are much more efficient at delivering water and you don't have a sump with them.

    If money is not an object, 90% is the way to go. If your budget is a concern, the 85% is still nice.

    American Standard owns Trane, you're essentially getting a Trane furnace, which are some of the nicest out there.

    With a 90% efficient furnace, you don't HAVE to use outside air, but it's recommended, and you would have to direct vent it to the outside. With any installation, you want to use outside air if possible.

    As always, choose a contractor that has taken the time to size your furnace and do a thorough job explaining it to you. Joe Hackjob is cheap for a reason.

    Good? Bad? I'm the guy with the gun.

  7. #7
    Join Date
    Jun 2005
    Location
    New England
    Posts
    906
    Thanks - not sure what you mean by a 'sump' for the humidifier

    mine is a skuttle 90SH and is pretty simple - with a foam pad drum on a small motor, a pan, and a h20 feed. Have they really improved upon this? (in fact, skuttle still makes it - a model 90 drum bypass humidifier)

    Dumb qn - why would outside air be better? Isn't it much colder?

    [Edited by jeffw_00 on 01-03-2006 at 04:29 PM]

  8. #8
    Join Date
    Jan 2002
    Location
    Ft.Worth,Tx
    Posts
    4,584
    It does not really matter equipment as much as design and if the system is installed properly..

    1) Is the system that I am choosing the right size for my conditioned space?
    2) Is the system that I am choosing calculated by load for sensible and latent heat.
    3) Is the contractor going to check my ductwork ; the amount of return air and combustion of my system.
    4) Is the contractor going to insure my safety,with inspection of system with local city inspector.
    5) Is the contractor going to cut corners to save himself money, or is he going to lay-out installation according to my homes needs,and will he be there in case of any warranty issues..Is the humidifier that is installed going to provide enough humidity control, and will I be able to maintain it, to manufacture recommendations.

    These would be some questions that I would maybe ask before I choose the right person for the job..

    <<<<<<<<aircooled>>>>>>>>>>>
    "Everyday above ground, is a good day".
    "But everyday that you have made a difference in someones life, may insure you stay above ground a little longer".<aircooled>

  9. #9
    Join Date
    Feb 2005
    Posts
    655
    [

    Dumb qn - why would outside air be better? Isn't it much colder?

    [Edited by jeffw_00 on 01-03-2006 at 04:29 PM] [/B][/QUOTE]

    Outside air is better because, if you use inside air you have
    already paid to heat it and will cause more infiltration of
    unheated air.
    using outside air =more efficiency.

  10. #10
    Join Date
    Jun 2005
    Location
    New England
    Posts
    906
    oh - right - positive (or is it negative) pressure - using outside air keeps unheated air out

    But what happens to the air filter and humidifier on the return?

    /j

    [Edited by jeffw_00 on 01-03-2006 at 05:12 PM]

  11. #11
    Join Date
    Feb 2004
    Location
    Central Kansas
    Posts
    1,145
    Regarding the air filter, you have no reason to be concerned. The air entering the furnace from outside is intended for the combustion processes only and should never intermix with houshold air. In other words, a pipe allows outside air into the burner chamber, it mixes with fuel for ignition and the resulting exhaust gases are piped back outside. The only times these two sources of air (outside combustion air and household air) can mix is if the heat exchanger is breached, cracked, etc. and household air is being polluted with combustion gases. You understand the theories behind not wanting to let your furnace use household air for combustion processes. The furnace will not be more efficient, but why burn up air you've paid to heat and then let the negative pressures pull more outside air into your home?
    Don't confuse me with facts, my mind is already made up.

  12. #12
    Join Date
    Jun 2005
    Location
    New England
    Posts
    906
    oh - ok - so there is still a 'return' for the household air
    /j

  13. #13
    Join Date
    Feb 2005
    Location
    Richmond
    Posts
    480
    [QUOTE]Originally posted by jeffw_00
    [B]oh - right - positive (or is it negative) pressure - using outside air keeps unheated air out

    But what happens to the air filter and humidifier on the return?

    /j

    The burners are sealed off with a box built around them so the return air and combustion air never mix.

    Edit: You beat me to it!

    [Edited by york_hvac on 01-03-2006 at 06:27 PM]

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