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ST9120U Schematic ( PDF Datasheet ) - Honeywell

Teilenummer ST9120U
Beschreibung Universal Electronic Fan Timers
Hersteller Honeywell
Logo Honeywell Logo 




Gesamt 12 Seiten
ST9120U Datasheet, Funktion
ST9120U
Universal Electronic Fan Timers
APPLICATION
The ST9120U 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
ST9120U 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
electronic fan timers also monitor limit switch strings and
energize separate ignition control systems through spst
pressure switches. The ST9120U can replace any
ST9101 or ST9120 listed in Table 2 below. The electronic
fan timers feature a field-adjustable heat fan-on delay, a
field-adjustable heat fan-off delay, a field-adjustable cool
fan-on delay and a fixed cool fan-off delay.
Electronic air cleaner (EAC) and humidifier (HUM)
convenience terminal connections are provided as an
option. Continuous low speed indoor air circulation is
also provided.
SPECIFICATIONS
Electrical Ratings:
Power Voltage Requirements: 18 to 30 Vac, 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.
Thermostat Load: 0.10A plus ignition system load.
INSTALLATION INSTRUCTIONS
On/Off Delay Settings:
Heat Speed:
Delay On: Field-adjustable, 30 or 60 seconds. Delay
timing starts when gas valve is energized.
Delay Off: Field-adjustable, 60, 100, 140 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: Fixed, 30 seconds.
Timing Tolerance: Larger of ±5% 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. File No.: MP466.
Canadian Standards Association File No.: LR95329.
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.
®
69-0644-1






ST9120U Datasheet, Funktion
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
THERMOSTAT
WY G R
AUX
VENT
ROLLOUT
MAIN
LIMIT
X
C
A
SC
C
HC
EO
AO
TL
N M1 M2
PRESSURE
SWITCH
MV
MV
GAS VALVE
STARTER
CAP
LO
HL
HH
HI
CIRCULATING
FAN
24
VAC
120
VAC
TRANSFORMER
CW23
COMBUSTION
AIR BLOWER
N
TO 120 VAC
POWER SUPPLY
L
INTERLOCK
M2547A
Fig. 3. Typical ST9101 wiring connection in standing pilot system.
69-0644—1
6

6 Page









ST9120U pdf, datenblatt
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
Action
System Response
Limit switch string opens.
1. Thermostat and ignition system are de-energized and gas valve
closes.
2. Combustion air blower and circulating fan heat speed are ener-
gized.
Limit switch string remakes.
1. Combustion air blower remains energized for postpurge timing.
2. The circulating fan remains energized for the selected delay-off
timing.
3. Normal operation resumes.
Continuous circulating fan is connected.
(Optional connection to circulating fan low
speed tap.)
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, ST9120U
switches circulating fan to appropriate speed.
Electronic air cleaner is connected.
(Optional connection to 120 Vac electronic
air cleaner.)
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
S1. Line voltage hot lead is also connected in input S1.
Humidity control is connected.
Humidifier is energized when combustion air blower is energized.
(Optional connection to 120 Vac humidifier.)
Automation and Control Solutions
Honeywell International Inc.
Honeywell Limited-Honeywell Limitée
1985 Douglas Drive North
35 Dynamic Drive
Golden Valley, MN 55422
Scarborough, Ontario M1V 4Z9
customer.honeywell.com
® U.S. Registered Trademark
© 2005 Honeywell International Inc.
69-0644—1 M.S. Rev. 11-05

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