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Thread: Mismatch?

  1. #1
    Join Date
    Aug 2008
    South Carolina
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    Morning all!

    The other week I ran across a Carrier system that had a 4ton Cond and Evap. However, the furnace was a 110k 80% furnace with a 3 ton drive...

    Would that affect any performance? It seemed to have worked for the last 2 summers. Seems to be functioning okay with a 22 degree split.

  2. #2
    Join Date
    Jan 2008
    Elkton, MD
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    As you are aware you have ~1200 CFM of airflow when you have a requirement for 1600CFM.

    Many manufacturers will allow the system to operate at a minimum of 350CFM per ton which would still require 1400CFM for the 4 ton system.

    What you will encounter is a low sensible capacity, high latent capacity with the possibility of a frozen coil if the airflow becomes restricted or if the system is operated at low ambient conditions.

    This could also lead to compressor floodback which will eventually damage the compressor.

    I am more interested in the superheat and subcooling along with indoor and outdoor conditions. The temperature drop may be high for the evaporator entering air conditions.

  3. #3
    Join Date
    Mar 2008
    Houston, Texas
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    Need more information to make any call on the mismatch. It could be a 3 / 4 furnace. It could also be a "4 ton" condenser with 40,000 btu compressor.

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