COOLLINKS PLC CONTROLLER

Sequences the operation of two air conditioners to ensure the most efficient conditioning of the space and the most balanced use of HVAC units.

The Marvair PLC-based CoolLinks controller sequences the operation of the two Marvair ComPac II units (models ASDCA, ASDCHA, HSDCA) to ensure the most energy-efficient conditioning of the shelter space and the most balanced use of the conditioning equipment. The CoolLinks system determines the need to cool or heat the shelter based on an indoor temperature sensor and outside temperature/humidity sensor connected directly to the controller.

Lead/lag operation ensures that each unit receives equal runtime and therefore extends the operating life of the units. In the event that one of the units is unavailable, for example, scheduled maintenance, the system will automatically select the active unit. Similarly, if the internal shelter temperature continues to rise/fall, the system will run both units. 

When cooling is required, the CoolLinks controller first examines the external shelter conditions to establish whether DC Free Cooling is possible. If acceptable, the 100% full flow economizer damper on the lead unit is opens to use outside air to cool the building. 

The CoolLinks controller communicates with the Marvair air conditioners over Ethernet. An Ethernet connection is also provided for a SNMP interface through which the Network Operations Center can receive traps (alarms), monitor/change cooling and heating set points, and monitor HVAC unit and system operational parameters. 

ALARMS AND LOCKOUTS

Each air conditioner and the shelter are monitored over Ethernet and if a problem is detected, an alarm is generated. The alarm is displayed on the CoolLinks PLC in the shelter and sent via SNMP v2C trap to the network operations center.

REMOTE ACCESS DATA POINTS

Through the Ethernet connection, the network operations center can monitor and change various data points in the HVAC system and the shelter.
Data Points which can be monitored and changed:

• First Stage Cooling Set Point Temperature

• Second Stage Cooling Set Point Differential Temperature

• First Stage Heating Set Point Temperature

• Second Stage Heating Set Point Differential Temperature

• Data points which can only be monitored:

• Inside Temperature - Current

• Outside Temperature - Current

• Outside Humidity - Current

• Dew point - Current

• Inside Temperature - Average Last Hour

• Outside Temperature - Average Last Hour

• Outside Humidity - Average Last Hour

• Dew point - Average Last Hour

• Unit 1 & Unit 2 Mechanical Cooling Time - Last Hour

• Unit 1 & Unit 2 Mechanical Cooling Requests - Last Hour

• Unit 1 & Unit 2 DC Free Air Cooling Time - Last Hour

• Unit 1 & Unit 2 DC Free Air Cooling Requests - Last Hour

• Unit 1 & Unit 2 Heating Time - Last Hour

• Unit 1 & Unit 2 Heating Requests - Last Hour