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  1. #1
    Join Date
    Feb 2001
    Posts
    445

    Question swapping ECM for PSC fan motors

    I know a HO who runs the fan on his Ruud UBHC-17J11NFD air handler (2.5 ton heat pump) continuously in the summer to help keep the temperature a bit more consistent between the upstairs and downstairs, so he figures swapping the OEM PSC fan motor for an ECM motor, such as the Evergreen, might pay for itself. The Evergreen mfr/distributor says the following:

    "No stock catalog replacement motor is an exact replacement for an OEM Factory Authorized part, standard stock PSC motor or ECM motor. It's the contractors job to ensure proper airflow to meet cooling or heating needs as required for the OEM equipment, and ensure that can be achieved when replacing an OEM motor with a generic replacement motor.

    The OEM body of motor in this system is 4.48" long with a 3.25" shaft.

    The Evergreen AH, which would be my best recommendation for an ECM replacement, pending fit, is 5.75" long with a 5" shaft.

    Both motors are standard 48Frame (5.6") diameter motors.

    Many Rheem systems also have special Rheem mounting brackets that would not work with an Evergreen, the contractor would need to get a standard torsion flex or wire form mount to install the motor.

    Your contractor is the best person to determine mechanical fit.

    The Evergreen AH Model #6001 is the 1/2Hp CCW rotation (same rotation as the OEM motor). The lower 2 or 3 speed selections would be tried (5 available on the AH ) by the contractor to match the airflow of this OEM 2 speed 1/4Hp motor."

    The HO's contractor says, "I don't know what the savings would be versus the expense to install this motor. I don't think there are any savings, unless this is used as a variable speed motor which would require variable speed controls."

    So my questions are 1) Is it even physically possible to swap these motors, and 2) How soon, if ever, would the new ECM pay for itself?

  2. #2
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,702
    My understanding of these motors is they save a lot IF the ductwork is not undersized. If they have to ramp up in an attempt to make airflow, the savings drops exponentially. So how much it will save depends upon how oversized the equipment is relative to the ductwork.

    Hopefully someone more qualified will come along and confirm or correct.


    So, ideally these model paying for themselves in 3 years. Each situation needs to be assessed to determine 3, 4, 5, 10, or never.

    Age of the equipment should be more of a driver than it often is. If the furnace is 10 years old, now that you are considering investing $x??? to update it, are you throwing good money into a nearly fully depreciated asset that may need replacement shortly? Subtract that cost from a brand new 95% mod and how does the incremental cost of a brand new unit, and it's much greater savings, look?


    I encourage taking a step back and looking at the big picture. Start with an energy audit, put the ECM in as an option, and let the numbers speak for themselves.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  3. #3
    Join Date
    Feb 2001
    Posts
    445
    More info: The air handler and coils are about 6 years old, but the compressor is only 2 years old.

  4. #4
    Join Date
    Jan 2011
    Location
    Mich
    Posts
    90
    The G.E ECM mtrs Im familiar with are D.C brushless and hve a controller which is seperable from the mtr itself,but you would still need the circuit board,so I guess if your A.H doesnt hve that than no would be your answer,you cant swap them

  5. #5
    Join Date
    May 2007
    Location
    Dry as a bone Tucson
    Posts
    4,208

    Savings

    According to the literature, the savings comes during continous fan from the use of a low speed on off cycle.

    I love those things, ball bearings, quite.

    I prefer the ECHO-Techs tho.
    Some Talk, Some Do
    "keeping condensing pressures low and evaporator pressures high"
    Comfort is my goal
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