Honeywell ST9120B Mode D'emploi

ST9120B,U
Universal Electronic Fan Timers
APPLICATION
The ST9120B,U Universal Electronic Fan Timers
integrate control of all combustion blower and circulating
fan operations in a gas warm air appliance. This control
is the central wiring point for most of the electrical
components in the furnace. The basic purposes of the
ST9120B,U are to monitor the thermostat for heat, cool
and fan demands, run the induced draft blower motor
and run a circulating fan (up to two speeds) as required.
The ST9120B,U also monitors limit switch strings and
energizes separate ignition control systems through
pressure switches. The ST9120B,U can replace any
ST9101, ST9120, ST9141 or ST9160 listed in Table 3
below. The ST9120B,U features a field-adjustable heat
fan-on delay, a field-adjustable heat fan-off delay, a field-
adjustable cool fan-on delay and a field-adjustable cool
fan-off delay.
Electronic air cleaner (EAC) and humidifier (HUM)
convenience terminal connections and continuous low
speed indoor air circulation are provided.
SPECIFICATIONS
Electrical Ratings:
Power Voltage Requirements: 18 to 30 VAC, 50/60 Hz.
Contact Ratings:
Combustion Blower:
1.5A full load, 10A locked rotor at 115 VAC.
0.75A full load, 5A locked rotor at 230 VAC.
(Reduce full load rating by humidifier [HUM] load.)
Circulating Fan:
Heat-Cool speed:
15A full load, 30A locked rotor at 115 VAC.
7.5A full load, 15A locked rotor at 230 VAC.
(Reduce full load rating by electronic air cleaner [EAC]
load.)
Continuous speed (optional):
8A full load, 16A locked rotor at 115 VAC.
4A full load, 8A locked rotor at 230 VAC.
EAC and HUM:
0.8A maximum combined load at 115 VAC
0.4A maximum combined load at 230 VAC
Thermostat W Load: 100mA at 24 VAC, plus ignition sys-
tem load.
Thermostat G, Y, Primary Limit, Burner Limit, Pressure
Switch Load: 22mA at 24 VAC load/cleaning current.
INSTALLATION INSTRUCTIONS
On/Off Delay Settings:
NOTE: Timing is derived from 24 VAC supply frequency
and is valid for 60Hz. At 50 Hz, the timings are
lengthened 20%.
Heat Speed:
Delay On: Field-adjustable, 30 or 60 seconds. Delay
timing starts when gas valve is energized.
Delay Off: Field-adjustable, 60, 120, 150 or 180 sec-
onds. Delay timing starts when gas valve is de-
energized.
Cool Speed:
Delay On: Field Adjustable, 4 or 30 seconds.
Delay Off: Field Adjustable, 30 or 60 seconds.
Timing Tolerance: Larger of ±2% or ±2 seconds.
Post Purge Timing:
5 seconds.
Environmental Ratings:
Temperature: -40°F (-40°C) to +175°F (+79°C).
Humidity: 5 to 95 percent, noncondensing.
Approvals:
Underwriters Laboratories Inc.
INSTALLATION
When Installing this Product...
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a
hazardous condition.
2. Check the ratings and specifications given in the
instructions and on the product to make sure the
product is suitable for your application.
3. Installer must be a trained, experienced service
technician.
4. After installation is complete, check out the product
operation as provided in these instructions.
WARNING
Electrical Shock Hazard.
Can cause severe injury, death or property
damage.
Disconnect power supply before wiring to prevent
electrical shock or equipment damage. More than
one disconnection can be required.
69-2252EF—07