Honeywell ST9120B Mode D'emploi page 15

Continuous circulating fan is
connected. (Optional connection to
circulating fan low speed tap)
Electronic air cleaner is connected.
(Optional connection to line voltage
powered electronic air cleaner)
Humidity control is connected.
(Optional connection to line voltage
powered humidifier)
Error Condition
Burner limit open (ST9141)
Limit open (ST9120)
Primary limit open
Pressure switch improperly closed
or pressure switch open when
Inducer is running
Overheated
Smart Valve II limit open
Twinning error – packet loss ratio
(PLR) greater than 78% (~10 sec
drop-out)
AC-line error for more than 10 sec
Table 9. ST9160 Operation Mode. (Continued)
1. Circulating fan low speed is energized when there is no call for heat, cool,
or fan.
2. If fan operation is required by a call for heat, cool, or fan, ST9120B,U
switches circulating fan to appropriate speed.
1. In two-speed systems, the electronic air cleaner is energized when the
heat or cool speed of the circulating fan is energized.
2. If continuous fan option is used, connect EAC to line voltage input L1.
1. Humidifier is energized when there is call for heat.
Table 10. Error Conditions.
1. Inducer relay is energized.
2. If the thermostat Y terminal is energized then circulating fan shall run at
cool speed otherwise the circulating fan shall run at heat speed.
1. If the thermostat Y terminal is energized then circulating fan shall run at
cool speed otherwise the circulating fan shall run at heat speed.
2. If there are three consecutive primary limit open events longer than
150sec, then it issues the overheated error condition.
1. The ignition system will not be energized.
1. All output relays are de-energized.
2. The device must be power-cycled to get out of this mode.
1. Inducer blower relay is energized.
2. If the thermostat Y terminal is energized then circulating fan shall run at
cool speed otherwise the circulating fan shall run at heat speed.
1. All twinning line communication is ignored.
2. The PLR must drop below 40% (~5 sec recovery) to resume further
attempts for twinning communication.
1. All output relays are de-energized.
2. Any change of the T-stat inputs is ignored, any information on the twinning
bus is ignored.
3. The device resumes normal operation after 120 sec of proper AC-line con-
dition.
ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS
Operation
15 69-2252EF—07