York R-407C Stand Alone Control, CV Specific Sequences, Cooling Operation Thermostat Control

Controls (continued)

Stand Alone Control

If the unit is not configured for Thermostat or Zone Sen- sor operation, the unit will operate in Stand Alone Mode.

In Stand Alone Mode, the OptiLogic™ Controller will monitor only the Occupied/Unoccupied state. When the unit is commanded into the Occupied Mode of opera- tion, the OptiLogic™ Controller will start the Supply Fan. If the unit is equipped with an Economizer, the Control- ler will check to see if Outside Air conditions are suit- able for Economizing. The controller will then use Out- side Air (when available and suitable) and/or stage com- pressors up and down, as required, to maintain the VAV Low SAT Setpoint.

CV SPECIFIC SEQUENCES

Cooling Operation

Thermostat Control

If a 7-wire thermostat (2 Cool/2Heat) controls the unit, all zone temperature setpoint control is maintained at the thermostat. With this operation, the unit remains idle until it receives a stage call from the Thermostat. If “G” is called from the thermostat, the Supply Fan will start and all occupied functions (if equipped), i.e. venti- lation, economizer, etc. will be allowed to operate.

Stage 1 (“Y1”) Call

If Y1 is called and the unit is equipped with an econo- mizer, the control will check to see if the Outside Air is suitable for economizing. If conditions are suitable for economizing, the control will control the economizer and stage up compressors, as required, to maintain a high

SAT setpoint. If conditions are not suitable for econo- mizing or not equipped with an economizer, the control will stage up 50% of the compressors. This shall be maintained until Stage 1 is deactivated or Stage 2 is called.

Stage 2 (“Y2”) Call

If Y2 is called and the unit is equipped with an econo- mizer, the control will check to see if the Outside Air is suitable for economizing. If conditions are suitable for economizing, the control will control the economizer and stage up compressors, as required, to maintain a LOW SAT setpoint. If conditions are not suitable for econo- mizing or not equipped with an economizer, the control will stage up 100% of the compressors. This shall be maintained until Stage 2 is deactivated.

Zone Sensor Control

If a zone sensor controls the unit, the OptiLogic™ con- troller shall maintain all zone temperature setpoints. These setpoints are user selectable at the OptiLogic™ User Interface.

When a zone sensor is used for control, the OptiLogic™ unit controller will monitor the temperature within the space and control the unit accordingly. A closed-loop staging algorithm is used to stage compressors up and down as required to maintain the desired zone tempera- ture setpoint. If the unit is equipped with an economizer, Outside Air conditions are continuously monitored by the control to determine if conditions are suitable for econo- mizing. If conditions are suitable for economizing, the OptiLogic™ controller will modulate the Outside Air damper in addition to staging compressors up and down to maintain the zone temperature setpoint.

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