Honeywell ST9120B Mode D'emploi page 14

ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS
Thermostat begins call for fan.
(Terminal G is energized.)
Thermostat ends call for fan.
(Terminal G is de-energized.)
Primary Limit switch string opens.
Primary limit switch string closes.
Primary limit switch string is open
for more than 150 sec (on each of
three consecutive cycles).
Burner limit switch string opens.
Burner limit switch string remakes.
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)
Action
Thermostat begins call for heat.
(Terminal W is energized.)
Thermostat ends call for heat.
(Terminal W is de-energized.)
Thermostat begins call for cool.
(Terminal Y is energized.)
Thermostat ends call for cool.
(Terminal Y is de-energized.)
Thermostat begins call for fan.
(Terminal G is energized.)
Thermostat ends call for fan.
(Terminal G is de-energized.)
Limit switch condition is received
from the SVII control
Limit switch condition is removed
from the SVII control
69-2252EF—07
Table 8. ST9141 Operation Mode. (Continued)
1. Circulating fan is energized at heat speed
2. If a call for heat occurs, circulating fan continues to run at heat speed.
3. If a call for cool occurs, circulating fan switches to cool speed.
NOTE: Circulating fan can be switched off for one second during the transition
between the fan speeds.
1. Circulating fan is de-energized.
1. Thermostat and ignition system are de-energized and gas valve closes.
2. Inducer is de-energized.
3. Circulating fan is energized at heat speed. If there is a call for cool the cir-
culating fan switches to cool speed.
4. LED flashes twice.
1. Circulating fan turns off after the selected heat fan-off delay timing. Normal
operation resumes.
1. Inducer, circulating fan and ignition system are de-energized.
2. Control goes into lockout mode. Control remains in lockout until 24 VAC
power is removed and reapplied (control is reset).
3. LED flashes four times.
1. Thermostat and ignition system are de-energized and gas valve closes.
2. Inducer and circulating fan heat speed are energized.
3. LED flashes once.
1. Inducer remains energized for postpurge timing.
2. The circulating fan remains energized for the selected delay-off timing.
3. Normal operation resumes.
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 Inducer is energized.
Table 9. ST9160 Operation Mode.
1. Request for heat is sent to the SVII system control.
2. Main burner lights.
3. Request for heat speed fan is received from SVII system control.
4. Heat fan-on delay timing begins. When timing is complete, circulating fan
is energized at heat speed.
1. Request for heat to the SVII system control stops.
2. Heat fan-off delay timing begins. When timing is complete, the circulating
fan is de-energized.
1. Cooling contactor is energized.
2. Circulating fan is energized at cool speed after cool fan-on delay timing.
1. Cooling contactor is de-energized.
2. Circulating fan is de-energized after cool fan-off delay timing.
1. Circulating fan is energized at heat speed
2. If a call for cool occurs, circulating fan switches to cool speed.
NOTE: Circulating fan can be switched off for one second during the transition
between the fan speeds.
1. Circulating fan is de-energized.
1. Circulating fan heat speed is energized.
2. LED flashes five times
1. The circulating fan remains energized for the selected delay-off timing.
2. Normal operation resumes.
System response
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