Section 3 - Sequence Of Operation; Compressor Staging; Table 1 - 25 - 40-Ton R410A Compressor Logic - York J Series Manual

SECTION 3 – SEQUENCE OF OPERATION

COMPRESSOR STAGING

Constant Volume and Variable Air Volume stage com-
pressors as follows:
TABLE 1 - 25 – 40-TON R410A COMPRESSOR LOGIC
Compressor Logic Constant Volume
1 Compressor 1
Compressor 2
2
Compressor
3
3 or 4
Compressor
4
4 or 3
The OptiLogic™ controller has default programming for either 4 or 6 stages of cooling.
The R410A units are all 4 compressor, thus program for 4 cooling stages.
JOHNSON CONTROLS
Note that ASCD (anti short cycle delay) and Minimum
VAV
Run Time will take priority above Compressor total-
Compressor 1
ized run time. For example, when turning on the first
Compressor
stage, the control will determine which compressor
3 or 4
has the shortest total run time and also read the ASCD
Compressor
timers for each compressor. If the compressor with the
2, 3 or 4
shortest total run time has expired, it's ASCD, then that
Compressor
compressor will be started. If the compressor with the
2, 3 or 4
shortest total run time has not expired, it's ASCD but
the other compressor has, then the compressor with the
longer run time will be started.
FORM 100.50-NOM7 (808)
17
3