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Community and Q&A

Digital vs. VRF Scroll Compressors?

Lance Peters | Posted in Mechanicals on

I’m looking at two different heat pumps, one using a digital scroll and the other a VRF (variable speed) scroll compressor.

The digital scroll compressor modulates output by separating the scrolls on a duty cycle, essentially a mechanical way of turning the compressor on/off as necessary while keeping the motor running. Modulation is from 100-10%.

The VRF scroll compressor modulates output by varying the speed of the compressor. Modulation is from 100-30%.

Does anyone here have experience with comparing the two technologies? I’m going to assume the VRF system will be more efficient at the compressor level while modulating, but the drive electronics are going to have some inherent inefficiency (90% maybe?). The digital scroll system will likely have much less electrical losses in its controls, but the compressor itself uses more energy when it’s modulating due to the compressor freewheeling. The digital scroll will modulate down further, however, to 10% of its full output.

Anyone have any thoughts or links to good articles comparing the two? I’ve done some searching around and haven’t found anything concrete.

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  1. Lance Peters | | #1

    Bumping my question from a while back.

  2. Jon R | | #2

    As far as I know, all the top efficiency heat pumps use inverter speed control.

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