York ECO2 YPAL 050 - Manual (Page 80)

80 JOHNSON CONTROLS
FORM 100.50-NOM6 (1207)
Sequence of Operation
Constant Volume
The following conditions must be met in order for
Economizer Loading to function:
•
The outdoor air temperature must be greater than
the return air temperature.
•
Economizer must be installed but not active.
•
A call for fi rst stage compressor operation only
•
The unit must be confi gured as a Constant Volume
unit.
•
The unit must be in an occupied or unoccupied
cooling mode.
The sequence of operation is as follows:
•
When the supply air temperature is 0.1° F less
than the “SUPPLY AIR TEMP LIMIT COOLING
SETPOINT” the economizer damper will start to
open.
•
If the economizer damper opens 100% and the
supply air temperature is still 0.1° F less than
the “SUPPLY AIR TEMP LIMIT COOLING
SETPOINT” the Simplicity Control will turn off
the compressor per the Excessive SAT sequence
and close the economizer damper to its minimum
position.
•
When the supply air temperature is between
“SUPPLY AIR TEMP LIMIT COOLING
SETPOINT” and the “SUPPLY AIR TEMP
LIMIT COOLING SETPOINT” plus 5.0° F the
economizer damper movement will stop and
maintain the current position.
•
When the supply air temperature is equal to 5.1°
F or more above the “SUPPLY AIR TEMP LIMIT
COOLING SETPOINT” the economizer damper
will close back to its minimum position.
Variable Air Volume
The following conditions must be met in order for
Economizer Loading to function:
•
The outdoor air temperature must be greater than
the return air temperature.
•
Economizer must be installed but not active.
•
A call for fi rst stage compressor operation only.
•
The unit must be confi gured as a Variable Air
Volume unit.
•
The unit must be in an occupied or unoccupied
cooling mode.
The sequence of operation is as follows:
•
When the supply air temperature is 5.1° F less
than the “VAV COOLING SUPPLY TEMP UP-
PER SAT SETPOINT” or “VAV COOLING
SUPPLY AIR TEMP LOWER SETPOINT” the
economizer damper will start to open.
•
If the economizer damper opens 100% and the
supply air temperature is still 5.1° F less than
the “VAV COOLING SUPPLY TEMP UPPER
SAT SETPOINT” or “VAV COOLING SUPPLY
AIR TEMP LOWER SETPOINT” the Simplicity
Control will turn off the compressor close the
economizer damper to its minimum position.
•
When the supply air temperature is between
“VAV COOLING SUPPLY TEMP UPPER SAT
SETPOINT” and the “VAV COOLING SUPPLY
TEMP UPPER SAT SETPOINT” plus 5.0° F
the economizer damper movement will stop and
maintain the current position.
•
When the supply air temperature is between
“VAV COOLING SUPPLY TEMP LOWER SAT
SETPOINT” and the “VAV COOLING SUPPLY
TEMP LOWER SAT SETPOINT” plus 7.0° F
the economizer damper movement will stop and
maintain the current position.
•
When the supply air temperature is equal to 5.1°
F or more above the “VAV COOLING SUPPLY
TEMP UPPER SAT SETPOINT” and 5 minutes
has expired since the economizer damper started
to open, the economizer damper will close back
to its minimum position and a second compressor
will come on.
•
When the supply air temperature is equal to 7.1°
F or more above the “VAV COOLING SUPPLY
TEMP LOWER SAT SETPOINT” and 5 minutes
has expired since the economizer damper started
to open, the economizer damper will close back
to its minimum position and a second compressor
will come on.