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Slow down a fan speed.

Discussion in 'Electrical Engineering' started by Mike Coonrod, Jan 26, 2006.

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  1. Mike Coonrod

    Mike Coonrod Guest

    Electrial experts,
    I have a hot dawg heater and would like to slow down the very powerful
    fan that clicks on after the burn chamber gets hot, it is too loud in my
    garage, drowns' out the football game. I looked at the heater itself
    and I can NOT select any other options on the control board to set the
    speed. Also, the fan on the back of the heater that I want to slow down
    has a start capaciter, and I don't know is that is important but it may
    be. Can I just look at the amp rating on the fan and add a reostat in
    line with the feed to the motor? (I took two years of electronic backin
    the 80's but don't use in day in and day out)

    I have a call into Modine, the makers of the heater, but they do not
    seem that user friendly. Thanks in advance.

    Mike in cold Minnesota.
     
  2. Pop

    Pop Guest

    There are ways to control inductive motor speeds, but
    unfortunately a resistive solution isn't one of them. As you
    decrease the current to a motor, the current increases sometimes
    to the point of catastrophy. More likely the temp would rise
    until an internal winding temperature sensor shuts the fan down.
    Sometimes they are self resetting, sometimes not.
    Check into motor controllers for a better solution.
    Pop
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    ..
    : Electrial experts,
    : I have a hot dawg heater and would like to slow down the very
    powerful
    : fan that clicks on after the burn chamber gets hot, it is too
    loud in my
    : garage, drowns' out the football game. I looked at the heater
    itself
    : and I can NOT select any other options on the control board to
    set the
    : speed. Also, the fan on the back of the heater that I want to
    slow down
    : has a start capaciter, and I don't know is that is important
    but it may
    : be. Can I just look at the amp rating on the fan and add a
    reostat in
    : line with the feed to the motor? (I took two years of
    electronic backin
    : the 80's but don't use in day in and day out)
    :
    : I have a call into Modine, the makers of the heater, but they
    do not
    : seem that user friendly. Thanks in advance.
    :
    : Mike in cold Minnesota.
    :
     
  3. sQuick

    sQuick Guest

    I wouldn't recommend slowing it down. The fan was designed to run at
    that speed for a reason.

    Maybe look at replacing the fan with a quieter one of the same speed.

    sQuick..
     
  4. operator jay

    operator jay Guest

    I agree, and to elaborate for the OP, slowing down the fan may allow the
    unit to overheat.
     
  5. Bud--

    Bud-- Guest

    If it is gas fired yes.

    Old Modine units were a hot water/steam radiator with fan forced air
    through it. If it is one of these reducing the air flow shouldn't be a
    problem.

    Noise, air flow and power consumed fall off rapidly with lower speed,
    What I remember is square law for air flow and power vs. RPM.

    Do you get a lot more heat than you need - you will loose capacity fast
    with lower speed.

    Lower speed motor (which can be lower power).
    Dual speed motor.
    Different fan blade.

    bud--
     
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