4 stages cooling with only 2 piping circuits

[tbedford]

Good morning, I hope everyone is staying safe during Covid precautions.

To provide some background, my installation is in a school in Edmonton, Alberta, Canada. A Daikin RCS045D condensing unit with 4 compressors provides cooling and hot gas bypass if required. The condensing unit is internally wired for the possibility of 4 stages of cooling. The designer has only provided design for two line sets from the condensing unit to the air handler. Each line set comes with a liquid line solenoid. Each liquid and suction line is sized correctly for the two compressors operating concurrently. The supply air temperature is controlled by a BMS system. The BMS system will enable the Daikin unit.
Two questions:

1. Can I expect poor oil return if only 1 stage of cooling is energized?

2. Apart form the lack of efficiency operating with only 2 liquid line solenoids are there any other capacity issues I can expect.

Cheers,

Tom

 

[EnergyProfessional]

The equipment manufacturer can tell you what piping options are possible. Oil return is one of their main considerations in writing up their guidelines.

 

[nglty]

Nowadays, digital compressors are specified in lieu of hot gas by-pass. check with your vendor.