McQuay screw compressors 1

[wj33]

I am looking for some history on McQuays screw chiller (mono screw) relative to compressor failures they have had and causes.
I believe this compressor is no longer manufactured but was approx 5 years ago

 

[absrbrtek]

The single rotor screws they use are the same as JE Hall. The Hall screw has been around forever with a good track record. With the Hall screw they use positive displacement oil pressure that is why it lasts.

With the McQuay screw they are trying to lubricate it with the 3% or 4% of oil mixed in the refrigerant, hence all the failures. They have since gone to a positive displacement oil setup with a seperator, this has improved the failure rate.

They also use Plastique gate rotors which fail almost on a regular basis. The original gates were compliant type which had no tolerance for floodback, the newer non compliant gates where they put a beveled washed under it to give it some additional tolerances have also helped.

IMO I wouldnt sell one. If the customer wanted one it would only be sold with the 5 year extended warranty. If you need a chiller thats dependable this wouldnt be high on my list. JMHO