[rainbowzootsuit]

Yes, they do tend to be quieter, and as far as I know are the only kind on inverter drive AC compressors. It's also a continuous process without having peaks and valleys in the motor load which probably lends itself to work well with an inverter drive, but I'd have to think about it a little more to say if that's accurate.

I did go back and look that there are sometimes valves used in scroll AC compressors. Even with that the full compression cycle is much more gradual, and continuous happening over ~3 revolutions of the compressor instead of half a revolution for a piston so there's not a slug compressed gas to hold the compressor back in the same way as a piston compressor.

This pages has some diagrams that shows the spiral plates and compression cycle pretty well. https://www.sciencedirect.com/topics/engineering/scroll-comp...

[c_o_n_v_e_x]

I did HVAC work in the late 90's till the late 00's. At that time, only the really expensive, high SEER rating units were variable speed. Cheaper 10-13 SEER systems had scrolls but they were fixed speed.

[jcims]

Awesome, thank you!