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  1. #1
    Join Date
    Oct 2005
    N Metro Atlanta GA
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    You guys really gave some good information when I was looking to replace my old system!
    But I have more questions now (after a long description):

    Trane dual fuel installed in ventilated attic in November 05:
    TUD080R9V4K4 + RXC037S3HPD0
    TAYPLUS130A (I don't know why; was not on proposal)
    VisionPro TH8321U

    From Furnace Installer's Guide: 400 CFM/ton temperature rise specs
    ......first stage: from 44 @0.1 ESP to 46 @0.9 ESP.
    ......second stage: from 49 to 48.

    I measured the rise from the return (2 ft from plenum but feeds through about 8-10 ft of flex) to the closest supply (about 10 ft from plenum, insulated metal duct, only one other supply, inside wall at end). The sensors have been tested and maintain identical temperatures under different conditions, i.e., the same relative to each other.

    Set point is 65 degrees.
    HP held 16-17 degree difference @ 25 degrees outside. Aux called.
    26-27 degree difference on Lo Fire; Stage 2 called by 10 minute furnace timer.
    34 degree difference on Hi Fire 10 minutes later.

    First, if you read all this, thanks.
    Second, even though the measurements are not accurate because they were not in the plenums, do these differences seem low to you?
    Third, is the VisionPro inside temp display for cosmetic purposes only? When I set a fan to blow warmer air from upstairs (on the floor under the return) down the stairway to the thermostat on the first floor, the temp displayed as 67. The heat still comes on with the 65 degree set point.
    The system is not zoned - that additional cost would have pushed the replacement price into 5 digits.

  2. #2
    Join Date
    Jun 2003
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    That sounds awful low to me. A heatpump will put out 95 degree air,+ or -, which at a 70 degree return air temp is 25 difference. For your furnace on high fire to put out 34 is awful IMO. Somethings not right and needs to be checked. Call them back.
    If everything was always done "by the book"....the book would never change.

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