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  1. #1
    Join Date
    Jan 2005
    Posts
    4
    I'm in a bind! gah

    I recently have a goodman 3 ton, 75k btu furnace installed into one of my rental properties. It heats an area thats about 1200sq foot with 8ft ceilings.

    I figured the math using what information i could find and the furnace should be plenty large.

    Anyway, after the install was done, it started getting really cold up here in michigan. My tenants have been calling me saying the furnace is not keeping up with the cold! Its getting as cold as 68 degrees inside. The house has new efficent windows but is not insulated well.

    I went to the basment to see if anything obviouse was wrong that might be a quick fix. This is the first time I examined the work. Everything looked nice and good, but he only used 8" round duct work and quite a bit of it is flex Duct work.

    The runs are fairly log, probably 15-18ft. I just don't think that duct work has enough area and is restricting the heat flowing to the house. On top of that the temp rise is only about 30 degrees! The heat going out is about 85-90.
    The heat bill is out f'ing standing.

    My primary house has a probably 20 year old 80% furnace and it blows 110 degree heat. It heats up the house (which is larger) fast and my heat bill is $300 less a month. I have poor windows with storms but they are very drafty. It is insulated though.

    My contractor says its an insulation problem, i disagree and say its a duct work problem.

    I'd get a 2nd opion, but we have but one contractor I've found willing to crawl in this space. Half the basement is a crawl space. Most contractors wanted me to do my own duct work and they will hook it up and check it. I guess in a small town you get to pick and choose your jobs.

    Thanks in advace for your help!

  2. #2
    Join Date
    Mar 2001
    Location
    North Carolina
    Posts
    428
    Originally posted by jaypee

    My contractor says its an insulation problem, i disagree and say its a duct work problem.
    I also disagree with the contractor as the insulation may be poor but that is taken in account when a heat load calculation is done and the system sized accordingly if no heat load was done then the unit size and the ducts are wrong most likely. and if you can not get satisfation from the contractor file a complaint with the state mechanical license board they sometimes have a way of getting things done

    [Edited by obxtech on 01-27-2005 at 12:24 AM]

  3. #3

    30 degree rise

    The fan must be set on high for heat, switch to medium and recheck the rise.

    Math? that's a new one on me. Click on the bullseye's for a load calaulation, you can't count it on thumbs.

    A good contractor "picks" his jobs in large towns too.


  4. #4
    Join Date
    Jan 2005
    Posts
    4
    Thanks guys,

    my main concern was the cold air return. I mean the furnace can only exhale what it breaths in. Its only breathing in though 1 eight inch tube ;/

  5. #5
    Join Date
    Apr 2003
    Location
    Iowa
    Posts
    763
    do the math a one 8 inch flex is about 150 cfm..... a 3 ton blower is about 1200 hmmmmm
    flex duct in a basement...... bet that job was the cheapest bid huh? Good thinkin

  6. #6
    Join Date
    Apr 2003
    Location
    Iowa
    Posts
    763
    if your restricted that much for air your heat rise should be outrageous, you sure you checked that right? 1 8 inch duct should be bouncin off limit big time.

  7. #7
    Join Date
    Jan 2005
    Location
    Seattle
    Posts
    191

    Wink duct work

    Airconman,
    ThaT should have been
    BIG,BIGGER,BIGEST
    {:TIME:}

  8. #8
    Join Date
    Jun 2003
    Location
    Hell Hole Swamp
    Posts
    4,180
    8" return? Please take some pictures and post them here in the "Wall of Shame" section.

  9. #9
    Join Date
    Feb 2004
    Location
    chicago suburbs
    Posts
    4,422
    HARD TO BELIEVE...

    1. Goodman equipment

    2. lots of flex

    3. BUTCHERED IN

    hmmmmm anybody see a pattern here?
    FILL OUT YOUR PROFILE!!

  10. #10
    Join Date
    Oct 2004
    Posts
    1,722
    Originally posted by jaypee
    Everything looked nice and good, but he only used 8" round duct work and quite a bit of it is flex Duct work.

    Most contractors wanted me to do my own duct work and they will hook it up and check it.
    Eight inch duct coming off the unit??? and...

    Most contractors want you to do your own ductwork, but they will check it? What is this...a homework assignment? I've never heard of such a thing.

    Get back to work.

  11. #11
    Join Date
    Apr 2004
    Location
    Niantic, Illinois
    Posts
    545
    Originally posted by airconman
    if your restricted that much for air your heat rise should be outrageous, you sure you checked that right? 1 8 inch duct should be bouncin off limit big time.
    That's what Im saying. I know the heatrise should be tripping the limit.

  12. #12
    Join Date
    Apr 2003
    Location
    Iowa
    Posts
    763
    Well I may not know much, but the only time I use flex is in an attic and most of that is insulated steel..... or a crawl space I can't fit thru and I can't slide steel thru it...
    If I came home to a basement with flex in it.... IT WOULD BE ONNNNNNNNN THENNNNNN!!!!

  13. #13
    Join Date
    Apr 2004
    Location
    Niantic, Illinois
    Posts
    545
    Another thing I thought of is maybe they fired the furnace after installation and it was tripping the limit. So they addressed that by turning up the blower and down the gas pressure. Instant low heatrise and poor performance.

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