York J Series - Compressor Average Run Times; Supply Fan Operation

JOHNSON CONTROLS
18
FORM 100.50-NOM7 (808)
Unit Sequence of Operation
COMPRESSOR AVERAGE RUN TIMES
To increase system reliability, all compressors will be
staged up (ON) based on average run time. The com-
pressors with the shortest average run time will always
be energized rst in an attempt to equalize run time.
SUPPLY FAN OPERATION
Minimum O Time
The Supply Fan minimum OFF time is as specied in
Table 2 under section on Timeouts and Delays.
The Supply Fan will be ON prior to:
• Starting any compressors.
• Turning ON any gas or electric heating stage.
• Opening any heating valve.
Overrun
The Supply Fan will continue to run for 1 minute af-
ter all compressors or heating stages turn OFF unless
otherwise stated. When in Thermostat operation, the
overrun requirement will override the loss of the G input
from the Thermostat.
For gas or electric heat, the Supply Fan will continue
to run until the SAT is less than 100°F.
CV Operation
For CV operation:
• The Supply Fan will be ON whenever the G input
from the Thermostat is present.
• The Supply Fan will stay ON when the G input is no
longer present to satisfy the Overrun requirement.
• In Space Sensor, or the Supply Fan will be ON
whenever:
• Heating or cooling is called for.
• the Fan On with Sensor parameter is ON and
occupancy is indicated.
VAV Operation
For VAV operation:
• The Supply Fan will be ON at the specied output
level whenever occupancy is indicated.
• When occupancy is not indicated the Supply Fan
will be ON at the specied output level when-
ever:
• unoccupied cooling or heating is called for.
• the Thermostat G input is present and the
VAV with Thermostat parameter is ON.
• In the Heating Mode, the Supply Fan will be at
100% output when ON.
• In the Cooling Mode, the Supply Fan will be op-
erated to maintain the Duct Static Pressure setpoint
when ON.