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IM 777-18 • SKYLINE OUTDOOR AIR HANDLER
Wiring/Controls
Single Furnace
2-Stage Controls
Sequence
When system is powered up 24 VAC will be applied to the
ignition control (IC) terminals 24VAC/GND. The control will
reset, perform a self-check routine, initiate full time flame
sensing, flash the diagnostic LED for up to four seconds and
enter the thermostat scan standby state. Call for Heat
1. Thermostat (controller) closes on call for heat powering
terminal T2.
2. 24 VAC is supplied to IC terminal Tstat, provided limit
switch is in closed position.
3. The control will check that pressure switch contacts are
open (IC terminal APS (PSW) is not powered).
4. The Induced Draft Fan (ID Fan) is then energized at high
speed through IC terminal IND.
5. When the Air Switch (APS-1) closes, a 15 second pre-
purge period begins.
6. At end of pre-purge period, the spark commences and
either 1st stage or both 1st and 2nd stage gas valves
(depending on status of call for heat) are energized for
the trial for ignition period.
7. If the thermostat (controller) is calling for 1st stage
heat only, the 1st stage valve will open (1.0 to 1.4" w.c.
manifold pressure on Natural Gas or 2.5 to 3.0" w.c. on
Propane Gas). If the thermostat (controller is calling for
high heat, both 1st and 2nd stage valves will open (3.3
to 3.5" w.c. manifold pressure on Natural Gas or 9.5 to
10.0" w.c. on Propane Gas).
8. Burners ignite and cross light.
9.
When flame is detected by flame sensor the spark is
shut-off immediately and gas valve(s) and combustion
blower remain energized.
10. During heating operation, the thermostat, pressure
switch and main burner flame are constantly monitored
to assure proper system operation.
11.
If the 2nd stage thermostat (controller) is satisfied, the 2nd
stage contact opens, de-energizing the 2nd stage valve.
Heater will continue to operate at 1st stage (low fire).
12.
When the thermostat (controller) is satisfied and the
demand for heat ends, the 1st stage valve is de-
energized immediately, the control senses loss of flame
and a 30 second post-purge occurs before de-energizing
the ID Fan.
Recovery from Lockout
1. If the thermostat (controller) is still calling for heat one
hour after a lockout occurs, the control will automatically
reset and initiate a call for heat sequence.
2. The ignition control may also be manually reset, by
turning the thermostat (controller) down and back up to
previous temperature setting or removing power (24V) to
IC terminal 24VAC.
LED Indications, Normal Operation
• Green, ½ sec ON, ½ sec OFF: Pre-purge, Inter-purge,
Post-purge
• Green, blinking rapidly: Trial for ignition
• Green, on solid: Flame detected, pilot/main burners on
ERROR CODES - Red Flashes Error Definition Error Type
•
1 flash, then pause No flame in trial time Lockout
•
2 flashes, then pause Flame sense stuck on Lockout
•
3 flashes, then pause Pilot/Main relay failure Lockout
•
4 flashes, then pause Repetitive flame loss error Lockout
•
5 flashes, then pause Rollout error Lockout
•
6 flashes, then pause APS Airflow error Lockout
•
7 flashes, then pause Internal control error Lockout ON
Solid Red Line Voltage/Freq Error Standby
