Looking for opinions, experiences, etc. with Copeland/Bitzer screw compressors. I am looking specifically at the SCA2/CSH (copeland model/bitzer model) R-134a optimized models.

These can either unload in 25% steps down to 25% or do the infinite unloading. I have heard many people (not necessarily in the know) mention how screws don't like to run unloaded for long periods of time. On the particular job where these are being considered, the engineers have specified a 10% turndown. The chiller will be dual circuit so I can do 12.5%, but that would mean a compressor would have to run indefinitely at its lowest unload setting.

I would be using these in air cooled process chillers.

Thanks for you input.