Instruction Manual

Screw Compressor Central Chiller Chapter 3: Installation 28
Checking Motor Direction
Compressor
Caution! Check Compressor Rotation Before Starting Unit!
Connect a phase monitor and phase incoming power ABC.
Note:
• Unit must be wired in sequence (ABC) and checked before start up.
• Never switch contactor leads or motor leads for reversing rotation.
• Do not use contactor or motor leads for phase matching.
• Compressor damage will occur if the compressor is run in reverse.
The compressor motor protector checks for correct phasing and will
not allow it to start in reverse.
• If you discover that phasing is reversed, correct it by switching any
two main power leads into the disconnect switch or distribution
block on the unit.
Water Pump
A positive pressure of > 20 to 30 psi (137.9 to 206.8 kPa/1.38 to 2.07 bars) on the TO
PROCESS line indicates correct pump rotation.
Condenser Fan
On central chillers with remote air-cooled units, air should draw through the condenser and
discharge up from the condenser.
Changing fan rotation direction
• Disconnect and lock out power at the fused disconnect.
• If all fans are going backwards, reverse any two main power leads.
• If only some of the fans are going backwards, switch any two of their
respective motor leads.
3-5 Initial Start-up
Pre-Startup Checks
Note: These lists assume the installation information in this manual have been read
and followed.
Have new chillers started up and checked by a qualified refrigeration
service technician.
The manufacturer offers factory startup for your Screw Compressor Central
Chiller. Call the Manufacturers’ Service Department at for more details.