VFD Compressors with Electronic Expansion Valves

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Email from Clay Brown to Engineering on 1/22/20 

Subject: Electronic Expansion Valves for Copeland ZPV compressors

 

Effective immediately, all circuits with a Copeland ZPV variable speed compressor will have an electronic expansion valve for improved superheat control. Sales has been notified to include this on all factory orders, but if they have missed it, please make sure to have them add it to the factory order. Only the ZPV circuit will get an EEV, unless specified otherwise in the factory order.

 

Email from Clay Brown to Sales Departments on 1/8/20

Subject: Electronic Expansion Valves for Copeland ZPV compressors

 

The first group of teardown reports on the Copeland ZPV compressors show lack of lubrication as the suspected cause of failure, but the several most recent teardowns indicate dilution/washout/slugging as the mode of failure. The end result of both of these failure modes is similar, but the latter shows evidence of liquid back to the compressor. Liquid back to the compressor indicates a loss of superheat control.

To provide better superheat control across the wide operating range of the ZPV compressors, all refrigerant circuits with a ZPV compressor will be provided with an electronic expansion valve going forward. These valves more expensive than a thermostatic expansion valve, but the data suggests that the EEV is more appropriate choice to prevent liquid refrigerant back to the compressor. Unless required by the project specifications, standard single stage, digital or tandem compressors will have a standard thermostatic expansion valve.

Please make sure that this is included in all future quotes and factory orders for units with ZPV variable speed compressors.