Chapter 3: System Operation
Sequence of Operation
Page 48
Sequence of Operation
Compressor and Heater Operation
Note: Diagrams based on Main Setpoint (Stp) = 77°F. For details on changing trigger points, please refer to
“System Parameters and Default Values” on page 58 for detail.
Lead Compressor
The lead compressor turns on at main setpoint +2 (configurable at C02 under E Menu).
The lead compressor turns off at 6 degrees beblow its turn on point (configurable at C01 under E Menu).
Note: Compressor engages a 3 min delay when the units are powered to prevent rapid compressor cycling.
Note 2: When outdoor temp is lower than indoor temp, the lead compressor will have a delayed start ranging from
10s to 300s to gives the system a chance to use FC before turning on the compressor.
Lag Compressor
The lag compressor turns on at main setpoint + 7.4 with 1 min delay (configurable at F38 under L05 Menu).
The lag compressor turns off at 7.2 degrees below its turn on point -7.2 (configurable at F39 under L05 Menu)
Lead Heater
The lead heater turns on at setpoint -27 (configurable at H02 under E Menu).
The lead heater turns off 3 degrees above its turn on point (configurable at H01 under E Menu).
Lag Heater
The lag heater turns on at setpoint -27 with 1 minute delay (configurable at F36 under L05 Menu).
The lag heater turns off 3 degrees above its turn on point (configurable at F37 under L05 Menu).
Free Cooling (Economizer) Operation
When the Free Cooling is engaged, the damper opens to introduce cooler air from outside to be delivered to the
shelter. The top exhaust design cause the exhaust air to be significantly hotter than the indoor temperature. This
allows small temperature difference between indoor and outdoor temperature (minimum 3.6F, connfigurable at
U06 under L04 Menu) to deliver large cooling capacity.
FC starts at low fan speed when indoor temperature reaches above the lead compressor turn off point. As the indoor
temperature rises, the fan speed increases to maintain the indoor temperature within 1 degree F of the main temp
setpoint. If the indoor temperature cannot be maintained below the lead compressor turn on point, the compressor
will start to assist FC.
Note : For shelters without a secondary pressure relief (e.g. a barometric louvre), FC can be disabled when the
compressor is running. (configurable at F04 under L05 Menu).
During cold weather, the outdoor damper modulates to keep mixed air temperature above 51.8 (configurable at
U54 under L04 Menu)
To Next Page
Loading...