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  1. #1
    Join Date
    Jul 2008
    Dorval, Quebec, Canada
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    Variable speed air handler questions

    I have a new Trane 2/4TEE air handler that reportedly has variable speeds. The trane site does not really explain how the unit decides what speed to run at a given time. Can someone explain please?

    Also I mentioned the speed mine is running at and the technitian told me they always run at high speed in A/C mode. Is that correct? Is there any speed adjustments that can be made by a homeowner ?

    As I have not had to use the unit for heat yet I don't know what speeds it will be running at. It is used with a heat bump and has a built in heating coil for the real cold weather. I'm in Canada.

    Thanks for any comments.


  2. #2
    Join Date
    May 2007
    DC Metro Area (MD)
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    The blower will ramp up to maintain proper airflow. It can ramp up to dehumidify if Comfort-R is enabled. It can also run at a lower speed for fan only.

    The speed is set by dipswitches in the unit. They're best adjusted by a professional. I'm not sure what high speed is, so I can't comment on that. Cooling CFM can vary--typically 350-450 cfm per ton depending on the climate.

  3. #3
    Join Date
    Nov 2005
    Linn Creek, Mo
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    High speed for cooling is setup according to size or A/C when the furncace is installed. The VS blower with try and maintain that speed according to the static pressure of your duct system. As static pressure in your ducts change (opening and closing of supply registers, filter getting dirty, ect) so will the speed of the VS blower to compensate for the changes to maintain the cfm's for your A/C, or heat.

    If setup with the right thermostat, it will also decrease the blower speed by a certain % in the cooling mode for dehumidification.

  4. #4
    Join Date
    Jan 2004
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    Your tech doesn't know how to set up an A/C correctly.

    Call and have that company send someone that knows how to set one up properly.

    Mis adjustments can cause troubles. So its not something for a customer to do himself.
    Techs misread the settings at times.
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    How many times must one fix something before it is fixed?

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