– The Simplicity Control uses the temperature difference calculated when the first com- pressor was turned on to verify the supply air temperature will not drop 5.0° F or more below the cooling “VAV COOLING SUPPLY TEMP UPPER SAT SETPOINT” or “VAV
COOLING SUPPLY AIR TEMP LOWER SETPOINT”. If turning a compressor on would result in the specified drop in supply air temperature, the second compressor will not be turned on.
•The same logic will be used to stage on compres- sor 3 and 4.
The Simplicity Control turns off compressor operation as follows:
•The supply air temperature is 5.0° F or more below the “VAV COOLING SUPPLY TEMP UPPER SAT SETPOINT” or “VAV COOLING SUPPLY AIR TEMP LOWER SETPOINT”.
•It has been more than
•The compressors will be turned off in the reverse order they were turned on.
Cooling – Unoccupied with Thermostat
The operation is the same as Occupied Cooling with a Thermostat except:
•A Y1 call will energize the supply fan.
•The Simplicity Control will not bring on compres- sors until the supply air temperature is 5.0° F or more above the “VAV COOLING SUPPLY TEMP UPPER SAT SETPOINT” or “VAV COOLING SUPPLY AIR TEMP LOWER SETPOINT”.
•Both of the above criteria must be met before the Simplicity Control will bring on compressors.
Occupied or Unoccupied Heating with a Thermo- stat
The following parameter must be programmed through the Simplicity Control:
•“VAV OCCUPIED HEATING ENABLED”
– must be turned on using Parameter 26 under the PROGRAM key on the Simplicity control board or under the HEATING SETUP tab in the Simplicity PC software package.
FORM
Any W thermostat input will energize all the available heat stages with a 30 second delay between stages.
Occupied Cooling with Hard Wired or Communi- cated Space Sensor
The following System Parameters must be programmed through the Simplicity Control for VAV operation with a space sensor:
•“VAV COOLING SUPPLY AIR TEMP UPPER SETPOINT” – using Parameter 23 under the PROGRAM key on the Simplicity control board or under the COOLING SETUP tab in the Sim- plicity PC software package.
•“VAV COOLING SUPPLY AIR TEMP LOWER SETPOINT” – using Parameter 24 under the PROGRAM key on the Simplicity control board or under the COOLING SETUP tab in the Sim- plicity PC software package.
•“VAV SUPPLY AIR TEMP RESET SETPOINT”
– using Parameter 25 under the PROGRAM key on the Simplicity control board or under the COOLING SETUP tab in the Simplicity PC software package.
The Simplicity Control will control the operation of the compressors as follows:
• If the space temperature is 2.0° F or more above the 5
“VAV SUPPLY AIR TEMP RESET SETPOINT” the control will use the “VAV COOLING SUPPLY AIR TEMP LOWER SETPOINT”.
•If the space temperature is not 2.0° F or more above the “VAV SUPPLY AIR TEMP RESET SETPOINT” the control will use the “VAV
COOLING SUPPLY AIR TEMP UPPER SETPOINT”.
•If the control is using the “VAV COOLING SUPPLY AIR TEMP LOWER SETPOINT” per above the space temperature must be equal to or less than the “VAV SUPPLY AIR TEMP RESET SETPOINT” before the control would switch to the “VAV COOLING SUPPLY AIR TEMP UP-
PER SETPOINT”.
•The control uses a
PLY AIR TEMP LOWERT SETPOINT”.
JOHNSON CONTROLS | 69 |
