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  1. #1

    Desperate questions from a father of three sweaty youngin's (and one sweaty wife)

    I think this is the right thread so here goes... I just bought a 115,00 btu, 95% efficiency, 14 seer, variable speed Amana furnace and Amana outside central air unit. I previously had a 20 year old Lennox outside central air unit and a Goodman furnace. My problem is that the air flow coming out of my ducts is less (not cooling as well) with the new units than with the older units and the new furnace's coils are freezing up when we run our air conditioning. The XXXX Heating and Air tech told me it is freezing up because I'm closing off the duct openings in the basement (we have a two story house with a finished basement). I closed the basement vents so more air flow would reach the second floor where our bedrooms are. The model number of the furnace and blower unit is AMVC951155DXAB. My question is: Is the tech right? Would closing the basement vents cause the system to freeze up, and why isn't there strong air flow upstairs? If he is right it means that I will have a freezing basement and a hot second floor. Also shouldn't the brand new units be blowing my hair back in my bedroom? It is a 5 ton air conditioner for 2500 sq. ft. of space. I know there isn't a problem with the duct work because of the good performance of the older unit. I am at a loss after financing $XXXX and not staying cool. Sorry for the long thread and thank you for any input!
    Last edited by Stamas; 06-18-2010 at 06:41 PM. Reason: Removed Co. Name and Pricing.

  2. #2
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    does it freeze up with the basement vents open? take a temp reading from a vent that blows and a reading from a vent that sucks. then close your vents in basement and imediatly recheck. Also measure the second floor temp, first floor temp and outside temp. log the model numbers of the furnace and outdoor unit then post your findings. typically closing 1 or 2 vents doesnt make a system freeze unless its already close to freezing. could be lack of air flow or incorrect refriderant charge.

  3. #3
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    If your closing off air that the system was design to move you can have freeze ups. Assuming that is the case something will have to be done to accommodate your airflow issues. The contractor should have been told what your were going to do so he could design for the home better. He also should have asked about the upstairs airflow.

  4. #4
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    pls post pix of sweaty wife......
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  5. #5
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    In most cases, just follow the advice given because the tech usually knows.

    Usually. Sometimes fixing problems is a process of elimination. Especially with a new set-up. Sometimes it takes multiple trips to nail down the problem.

    It is in warranty, don't feel bad about calling to report poor performance issues. That is a normal part of the mechanical business.
    "You boys are really making this thing harder than it has to be". Me

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  6. #6
    Ask the tech to bypass the variable blower stuff by setting the dip switches to run on high speed.
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  7. #7
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    5 tons for 2500 sq ft.
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    How many times must one fix something before it is fixed?

  8. #8
    I think if he has a poor duct system the variable furnace blower is never coming up to high speed.
    Have the tech set the sw to run on high speed all the time, just to see what goes.
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  9. #9
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    5 tons for 2500 SQ. FT. sounds OVERSIZED to me. Especially since half the house is a basement.
    I am an experienced, caring, trusted, service provider who solves my customers issues beyond there expectations by educating them and guiding them with value-building options to make excellent buying decisions while building security and wealth for my company, myself and my family.

  10. #10
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    Quote Originally Posted by Diceman View Post
    I think if he has a poor duct system the variable furnace blower is never coming up to high speed.
    Have the tech set the sw to run on high speed all the time, just to see what goes.
    I agree Dice, probably something to do with the varispeed issue. I think the tech on site has a 20x advantage to find the problem.


    Side note: Kinda tosses all that efficiency out when you just drift some cool air into the nearest or lowest outlet huh?
    "You boys are really making this thing harder than it has to be". Me

    "Who ARE you people? And WHAT are you doing in my SWAMP!?" Shrek

    Service calls submitted after 3PM will be posted the next business day.

    I give free estimates [Wild Ass Guesses] over the phone.

    "I am sorry for interrupting, please continue with your quarreling" Some chick on TV

  11. #11
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    Quote Originally Posted by Oldschoolmetal View Post
    5 tons for 2500 SQ. FT. sounds OVERSIZED to me. Especially since half the house is a basement.
    I agree!!
    Knowledge comes with experience

  12. #12
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    Nov 2004
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    5 tons for 2500 sqft? thats a ton for every 500sqft. I am going to go with way over sized unit.
    OP what temp do you have it set at? do you change the filters on a regular schedule.
    also from reading the post. I am starting to think the whole system is oversized. you have a 115k btu furnace at 95% for 2500sqft. that is a bit large even for here in Northern Indiana

  13. #13
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    May 2010
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    Quote Originally Posted by nickellhead View Post
    I agree!!
    I wouldn't necessarly agree. What is the load of the house, are there lots of windows, good insulation in the attic, walls? is the basement completly under ground or only partly underground, what was the size of the origonal equipment and most importantly was a Manual J performed before the installation was Started. Are there trunk dampers to adjust the air flow from one floor to the next for summer/winter that the tech may have adjusted improperly? I would agree with Stamos.
    Last edited by Thurmont HVAC; 06-19-2010 at 01:02 PM. Reason: grammar, Again!

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