Appendix G: Standard Field Wiring Terminals
Control Field Wiring
Low voltage terminal control consists of the following:
Electro-mechanical Controls Unit
Inputs
• Occupied ventilation timer/sensor
–
Dry contact
• Occupied recirculation (if equipped)
–
Dry contact
• Unoccupied recirculation (if equipped)
–
Dry contact
• Unit fault
–
Dry contact
• Cooling stage 1 (if equipped)
–
Dry contact
• Cooling stage 2 (if equipped)
–
Dry contact
• Heat enable (if equipped)
–
Dry contact
• Modulating heat (if equipped)
–
0 to 10 VDC
• Re-heat valve on/off 1 (if equipped)
–
Dry contact
• Re-heat valve on/off 2 (if equipped)
–
Dry contact
• Re-heat valve modulating (if equipped)
–
0 to 10 VDC
• Modulating supply motor speed (if equipped)
–
0 to 10 VDC
• Modulating exhaust motor speed (if equipped)
–
0 to 10 VDC
Outputs
• Supply fan on
• Exhaust fan on
• External unit fault
• Defrost on (if equipped with recirculation or exhaust
only defrost options)
• Free cooling on (if equipped with free cooling option)
• Wheel failure (if equipped with wheel rotation sensor
option)
• Dirty supply filters (if equipped with dirty filter sensor
option)
• Dirty exhaust filters (if equipped with dirty filter sensor
option)
• Cooling on (if equipped with cooling)
• Heating on (if equipped with gas heat)
IMPORTANT
All output controls are 24 VAC unless otherwise indicated.
24 VAC−
24 VAC+
SCR ELECTRIC POST-HEAT (0–10 VDC+) (OPTIONAL)
SCR ELECTRIC POST-HEAT (0–10 VDC−) (OPTIONAL)
SCR ELECTRIC POSTHEAT (SHIELD) (OPTIONAL)
FREE COOLING ON (OPTIONAL)
DIRTY SUPPLY FILTER (OPTIONAL)
DIRTY EXHAUST FILTER (OPTIONAL)
WHEEL FAILURE (OPTIONAL)
EXHAUST BLOWER ON
COIL LOW LIMIT (OPTIONAL)
24 VAC+
OUTPUTS
20 VA
MAXIMUM
SUPPLY BLOWER ON
HEATING (ON) (OPTIONAL)
COOLING STAGE 1 (ON) (OPTIONAL)
HOT GAS REHEAT MODULATING (0–10 VDC+) (OPTIONAL)
HOT GAS REHEAT MODULATING (0–10 VDC−) (OPTIONAL)
GAS HEAT MODULATING (0–10 VDC+) (OPTIONAL)
GAS HEAT MODULATING (0–10 VDC−) (OPTIONAL)
COOLING STAGE 2 (ON) (OPTIONAL)
SUPPLY BLOWER MODULATING (SHIELD) (OPTIONAL)
SUPPLY BLOWER MODULATING (0–10 VDC−) (OPTIONAL)
SUPPLY BLOWER MODULATING (0–10 VDC+) (OPTIONAL)
EXHAUST BLOWER MODULATING (0–10 VDC+) (OPTIONAL)
EXHAUST BLOWER MODULATING (0–10 VDC−) (OPTIONAL)
EXHAUST BLOWER MODULATING (SHIELD) (OPTIONAL)
COMPRESSOR ONE STATUS (OPTIONAL)
COMPRESSOR TWO STATUS (OPTIONAL)
CR
CR
CR
CR
CR
CR
CR
CR
CR
CR
CR
CR
CR
CR
CR
CR
UNOCCUPIED RECIRCULATION
CONTACT (OPTIONAL)
OCCUPANCY
CONTACT
COOLING STAGE 2
CONTACT (OPTIONAL)
GAS HEAT ENABLE
CONTACT (OPTIONAL)
RE-HEAT VALVE 2
CONTACT (OPTIONAL)
RE-HEAT VALVE 1
CONTACT (OPTIONAL)
SCR ELECTRIC HEAT ENABLE
CONTACT (OPTIONAL)
GAS HEAT STAGE 2
(OPTIONAL)
ELECTRIC HEAT STAGE 1
CONTACT (OPTIONAL)
ELECTRIC HEAT STAGE 2
CONTACT (OPTIONAL)
ELECTRIC HEAT STAGE 3
CONTACT (OPTIONAL)
ELECTRIC HEAT STAGE 4
CONTACT (OPTIONAL)
COOLING STAGE 1
CONTACT (OPTIONAL)
SUPPLY BLOWER HIGH SPEED
CONTACT (OPTIONAL)
EXHAUST BLOWER HIGH SPEED
CONTACT (OPTIONAL)
UNIT FAULT
371
363
370
310
311
312
313
309
308
302
301
304A
305
306
307
314
315
320
321
304
305
326
325
324
322
329
354
360
359
361
362
368
364
358
357
355
352
353
356
376
375
377
410
502
411
501
503
502-S
504
504-S
374
372
373
Figure G1: Electro-mechanical controls
VCES-VHC-IOM-1F – VHC-36, -42 & -50
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