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Thread: Amperage usage for Multi Stage Compressors

  1. #1
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    Amperage usage for Multi Stage Compressors

    I am trying to get accurate amperage usage for a dual stage heat pump compressor. I know that the compressor staging is 70%/100% for stage1/stage 2, and the the nameplate indicates a single RL of 15.3 amp.

    I just want to verify that the compressors amperage consumption for the stages is simple as 70%/100% of 15.3amp. Or does it not calculate out this nicely?

  2. #2
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    That's not how it works. Ambient temperature and load along with many other factors affect amps draw.
    It's more like a sliding scale with the 2 numbers you posted as the maximum numbers.
    Just figure that high stage is X. And low stage is 66%of X.
    You don't squat with your spurs on.
    And you NEVER put the torches away before pressure testing.

  3. #3
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    Thread Starter
    ah, makes sense. That actually makes my numbers even better if the compressor is averaging somewhere less than RL.

    Heck, if I assume a 24 hour HP runtime (includes the outdoor fan draw) at an average of 70%, the electric cost equates to 6.4 hours of a pure 10kW heat bank. It really is surprising then why people lock out their HP's in the 30's when the HP is maybe only running 10-15hr/day.

  4. #4
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    Yes I'm not much of a fan of locking out a heat pump until you hit the mid 20s.
    We have fairly cheap natural gas here and the economic balance based on 95% gas furnace is actually 20 degrees.
    My own place has only electric so I run the heat pump to about 5 degrees.
    You don't squat with your spurs on.
    And you NEVER put the torches away before pressure testing.

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  6. #5
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    A couple more very important notes : If you are going to lock out your HP during a cold spell make sure you have a working HP crank case heater. Defiantly a good way to a shortened life span of the compressor .

  7. #6
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    As it gets colder outside, a heat pump compressor will draw less amps. It will also provide less heat. Theoretically, a compressor running in low stage on a warm day might draw the same amount of amps or more than it would if it were in high stage on a really cold day.
    If at First You Don't Succeed, Skydiving Is Not for You.

  8. #7
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    You can try to calculate till the cows come home, and, you might come close...... or likely not.

    Why not install a couple data loggers and capture real time operating conditions?

    Simple, cheap, and accurate.

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