Protocol™ With 3-Pipe Gas Defrost - Hussmann Proto-Aire Installation Manual

Protocol™ with 3-Pipe Gas Defrost
Oil Return System Not shown
When 3-pipe gas defrost is used, hot gas is piped from the discharge line, after the oil
separator, to the cases. Solenoid valves are placed in both the suction and hot gas line so
that each system can be tuned on or off by the controller. Place a bypass line, with a check
valve ensuring that flow during defrost can bypass the TXV. A pressure differential
solenoid valve needs to be installed in the main liquid line to insure proper flow during
defrost. The pressure differential solenoid valve is factory installed in a vertical or
horizontal Protocol™. Ensure that during defrost no more than 45 lbs or 20% of the total
load is in defrost at any given time.
Pressure
Differential
Solenoid Valve
Case
S
Case
S
Case
S
Case
S
Suction Line
Filter
Liquid Line
Filter / Drier
Receiver
Sight Glass
Hot Gas Line
Discharge Header
Compressors
Suction Header
42
Protocol™ Installation and
Service Manual
Condenser
Turba-Shed
Oil Separator
Check Valve
S Solenoid Valve