# Copeland Ultratech 2 Stage Compressor - Opinions



## robinasu (May 11, 2016)

Hey all, I've been trying to learn more about the latest and greatest technology in our industry. I've read about the different modulating compressor technologies:

2-stage
Digital
Variable speed

From what I saw on youtube the copeland digital units don't seem to save much: unloaded 3.8A, loaded 5.8A. 

The variable speed stuff is pretty neat, but the drive electronics seem like a reliability issue, at least in the short term. Plus, the cost of all the electronics.

I like the 2-stage variable capacity compressors - simple modulation control, and you aren't wasting any energy like the digital compressors.

Seems to me if they made an ultratech 3 stage, we could modulate, for example, at 33%, 66%, and 100%, then PWM between the stages with pretty basic controls and no complex motor drives.

Does anybody think we need modulation below 33%? 

Does copeland not do this because at 33% the efficiency is too low? I read on the Emerson Ultratech website the Ultratechs are more efficient at 66% than the variable speed compressors.


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