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  1. #1
    Join Date
    Jun 2008
    Location
    st louis,metro
    Posts
    2

    not getting cold air

    I was wondering if an evac and recharge could help lower my air temp. i am currently getting 60degree air out of ducts seems a lil high. Service guy says my pressures are good and i need a new furnace. my furnace is old and ac is new. I know knothing about residential air but in car systems sometimes they build moisture causing warmer temps.

  2. #2
    Join Date
    Jun 2008
    Location
    st louis,metro
    Posts
    2

    pres

    what are good press. for a residential unit

  3. #3
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,037
    With home air conditioning it's mostly about temperature difference when you, the homeowner, are investigating whether or not your system needs attention.

    Measure the temperature being pulled in by the return air grills in your home. Next measure the discharge air temperature out of the closest register to the furnace. Subtract the discharge from the return to get what's called Delta T or temperature difference.

    Depending on the age, total system set up and other variables you should see a difference somewhere in the range of 16-20°F of Delta T.

    A properly installed residential central air conditioner is a permanately sealed system. For the life of the equipment there should never be (knock on wood) any reason for moisture to get in or a reason other some types of failures to ever need to take the charge out and replace it.

    The recommendation of a new furnace could be that the tech found the maximum air flow capacity of the old furnace doesn't match the requirements of the new AC.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  4. #4
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,033
    Quote Originally Posted by jmbowl300 View Post
    I was wondering if an evac and recharge could help lower my air temp. i am currently getting 60-degree air out of ducts seems a lil high. Service guy says my pressures are good and i need a new furnace. my furnace is old and ac is new. I know nothing about residential air but in car systems sometimes they build moisture causing warmer temps.
    First, everyone needs to know, at all times, the relative humidity in their home because it affects the SA/RA delta t & comfort. Springfield makes a very low priced TH & Relative Humidity gauge combo, it's available at many hardware stores.

    You provided NO data for making any opinionated judgments concerning whether 60-degree supply air was okay; specific conditions determine what the temp will be!

    View in linked page: Figure A18.1, Air Temperature Drop through Evaporator Coil.
    http://www.udarrell.com/air-conditio...tent-heat.html
    - Darrell

  5. #5
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,785
    You need a service tech that knows what he's doing.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

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