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  1. #1

    Blower Motor Energy Usage.

    I know about how an ECM variaable speed blower motor will use about the same amount of energy as a 100 watt light bulb. I'd like to know how much energy the normal blower motors use. I have a new G61MP 60C-111 and I'm just curious about it.

  2. #2
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    Spec sheet for my Goodman air handler with 3-speed PSC motor for my 3-ton heat pump says Full Load Amps = 3.39 for this 1/2 hp motor.

    If that is on high speed, low speed = 1.13 amps = 135 watts?

    Not sure if the amp draw going from hi to med to low is linear.

    Take care.

  3. #3
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    Apr 2002
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    A furnace used for heating purposes has the fan motor in the air stream, so all the heat produced by the motor is distributed into the living area.

    So, regardless of motor efficiency, the practical efficiency is around 100%. If the motor is relatively inefficient you'll use slightly more expensive electricity and slightly less lower cost gas.

    The advantages of variable speed and input come from other things.

  4. #4
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    In most if not all cases, the energy savings will be realized due to the improved control over the discharge air temperature..

    The best way to think about it is the throttle pedal in your vehicle, if you only had one speed, you would have to turn on and off the engine in slow traffic....

    The electrical savings on the motor is just a tiny part of it....

    GT
    If a day goes by and you have learned nothing, I hope you got a lot of sleep.

  5. #5
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    The electrical savings is very good if you're comparing running a psc motor continuously vs. running ecm continuously.

    If not comparing continuous running the electrical saving is minimal.

  6. #6
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    It depends if you're in the first or second stage of heating and what your external static pressure is. I have a G71MPP and in second stage at .50 static the blower motor uses 390 watts and at .80 static it uses 495 watts.

  7. #7
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    Quote Originally Posted by gary_g View Post
    Spec sheet for my Goodman air handler with 3-speed PSC motor for my 3-ton heat pump says Full Load Amps = 3.39 for this 1/2 hp motor.

    If that is on high speed, low speed = 1.13 amps = 135 watts?

    Not sure if the amp draw going from hi to med to low is linear.

    Take care.
    135watts/1.13amps=119volts

    You have an air handler that runs off of 120 volts???
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  8. #8
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    Quote Originally Posted by beenthere View Post
    135watts/1.13amps=119volts

    You have an air handler that runs off of 120 volts???
    No.

    220v.

    Good catch (again).

    Question BT: For a 3-speed PSC that is rated at 3.39 amps on high speed, does low speed amp draw = 1/3rd of high speed amp draw?

    Thanx.

  9. #9
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    Quote Originally Posted by stinkmeaner View Post
    I know about how an ECM variaable speed blower motor will use about the same amount of energy as a 100 watt light bulb. I'd like to know how much energy the normal blower motors use. I have a new G61MP 60C-111 and I'm just curious about it.
    Normally, a large furnace (111,000 Btu) will have a 4 ton blower (approx. 800 watts) or a 5 ton blower (approx. 1,100 watts).

  10. #10
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    Jul 2004
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    Massachusetts
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    I don't want to rain on anybody's parade here but some things need to be clarified.

    Static pressure is huge when it comes to ECM motors. The basic advantage of an ECM motor is that it will self adjust to variables, such as a dirty filter or someone throwing a rug over a return or closing a register damper. The motor will sense the increase in static and adjust to deliver the programmed CFM. However, in so adjusting, it will increase the watts/amps used to achieve that airflow. So if you have a system with high static, best to NOT use an ECM because it's going to use an awful lot of electricity to deliver the required airflow.

    Second, the only way to truly measure the amps of an ECM is with a true RMS ammeter. If you're not using a True RMS, you'll over state the savings of an ECM. Regular clamp-ons use an average amp reading and that's not a good reading when trying to read the pulsed power of an ECM.
    If YOU want change, YOU have to first change.

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  11. #11
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    best to NOT use an ECM because it's going to use an awful lot of electricity to deliver the required airflow.
    Isn't using more electricity to get the required flow rate better than not moving enough air?
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  12. #12
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    Quote Originally Posted by gary_g View Post
    No.

    220v.

    Good catch (again).

    Question BT: For a 3-speed PSC that is rated at 3.39 amps on high speed, does low speed amp draw = 1/3rd of high speed amp draw?

    Thanx.
    Your blower may have a RLA of 3.39amps.

    But it shouldn't be drawing that much amperage.

    Your amp draw won't drop by a 1/3 when going from high to low, on a 3 speed motor.

    Does tend to vary by manufacturer a bit though. As to how they did their winding taps.
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  13. #13
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    Quote Originally Posted by beenthere View Post
    135watts/1.13amps=119volts

    You have an air handler that runs off of 120 volts???
    Do all air handlers run off 220V?
    Bill

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