Rev.01 03-27-17
Page 11 of 71
Compu-Aire
3.0
SEQUENCE OF OPERATIONS
3.1
Standard Units in General
In general, the controller is operated as follows:
NOTE: The following are applicable while the controller is in active mode and only apply to DX and
Chilled Water units.
•
Fan starts up on demand for cooling, heating, humidifying or dehumidifying, or operates
continuously.
•
Sequences the compressors on in stages with adjustable delays to meet demand for
specified temperature and humidity setpoints.
•
Sequences the heaters on in stages with programmable delays to meet demand for heating
or reheat during dehumidification mode.
•
Activates the humidifier as needed to meet the humidity demand.
•
Dehumidification is achieved by means of cooling to reduce the humidity level. During the
dehumidification process, if the temperature falls below the room setpoint, heating is
brought on to reheat the air and maintain room temperature.
•
The controller monitors the complete system for any sensor, fan, compressor, heater,
and/or humidifier failure. Upon critical failures, the complete system will shut down with
alarm. For certain component failures, the applicable feature is disabled to ensure safe
operation. For example, when compressor failure occurs, the failed compressor shall be
locked out but the system shall provide cooling by other compressor if available. On a
heater failure, the heaters are locked out. The system will not use that function until you
manually reset on the display. The controller also keeps the history of last 100 alarms after
you reset them.
3.2
How to Turn the Unit ON
From the status screen, navigate to the On/Off menu and press enter. Use the Up/Down
arrow buttons to toggle the On/Off operation.
The System Status screen should indicate the current system operating mode.
Default time delay for evaporator fan is 30 seconds to avoid short cycling.
Unit will automatically control the necessary mode of operation to maintain room setpoints.
3.3
Lead/Lag Redundancy – pLAN Network
System 2500 series controllers can be set for n+1 redundancy setup. A maximum of 32 units can
be linked together on the pLAN network. The pLAN networked systems are identified by IP
addresses. Any system within the network can be configured as master unit. This alleviates the
need to cumbersome wiring with the use of standard Ethernet cables. In case of master unit is out
of service, any of the slave units can be set as a new master to reduce network downtime. No
wiring changes are needed. Each controller is self-dependent with necessary sensors and it can be
