Hussmann Proto-Aire Installation Manual page 105

Pull a vacuum to 1500 microns. If the vacuum fails to hold, determine the cause and
correct. Begin again and pull a vacuum to 1500 microns.
Break the vacuum with refrigerant vapor to a pressure of about 2 psig. Do not exceed the
micron gauge transducer's maximum pressure surge to the transducer of the micron gauge.
Pull a second vacuum to 1500 microns.
Break the vacuum with refrigerant vapor to a pressure of about 2 psig.
Pull a third vacuum to 500 microns. Close vacuum header valves and allow system to
stand for a minimum of 12 hours. If the 500 micron vacuum holds, charging may begin. If
not, the cause must be determined and corrected. Repeat the entire evacuation procedure
from the first step.
Pre-charge Check List
During any of the pull downs, check:
Merchandisers
Electrical requirements and power supply
Electrical connections tight and clean
Proper fan operation
Thermostat setting
Walk-in Coolers and Freezers
Electrical requirements and power supply
Electrical connections tight and clean
Proper fan operation
Thermostat setting
Water Loop
Electrical requirements and power supply
Electrical connections tight and clean
Proper pump operation
Proper fan operation
Thermostat or pressure settings
Damper operation, if equipped
Protocol™ Water valves set properly
Heat Reclaim and Other Systems
Electrical requirements and power supply
Electrical connections tight and clean
Component Operation
Refrigerant Charge
Remember the condenser in the Protocol™ hold only a small amount of refrigerant. It is
therefore very easy to overcharge the Protocol™ unless care is taken during the charging
process.
Charging until the liquid sight glass is clear of bubbles will often overcharge the system
causing head pressure alarms.
Protocol™ Installation and
101
Service Manual