CNT-SVX05A-EN
15
Binary inputs
Exhaust fan status
The exhaust fan status binary input IN 12 indicates the presence of air flow
through an exhaust fan associated with the controlled air handling unit. For
Tracer™ AH.540 applications, a differential pressure switch detects exhaust fan
status, with the high side of the differential being supplied at the outlet. During
exhaust fan operation, differential pressure closes the normally open switch and
confirms that the fan is operating properly.
A
Low Exhaust Fan Air Flow
diagnostic is detected during the following two
conditions:
• The controller is commanding the exhaust fan On and the status switch is not
in the closed position
• The fan status switch does not close the binary input within two minutes of the
controller commanding the exhaust fan On
This is a latching diagnostic but does not affect controller operation of the air
handling unit. Refer to the
Troubleshooting
section for additional details.
Table 16 — Exhaust fan status binary input IN 12 configuration
Note 1:
A
Low Exhaust Fan Air Flow
diagnostic is generated when the controller turns on the exhaust fan output, but
the exhaust fan status binary input indicates the exhaust fan is not running after a two-minute delay time.
IN 12 configuration
Contact closed
Contact open
Not used
Normal
Normal
Normally closed
Exhaust fan diagnostic (Note 1)
Normal
Normally open
Normal
Exhaust fan diagnostic (Note 1)