LG AR-DE12-05A, Installation And Operation Manual

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Sequence of Operation
Start-Up / Standby
Prior to start-up, verify that all field-installed sensors
have been installed. This includes a room temperature
sensor (optional) and a discharge air temperature sensor
(standard).
Heat Mode
When the unit or furnace controller calls for heat:
1. The ignition control will check that the pressure
switch for the combustion blower is open.
2. The combustion blower will energize and the
15 second pre-purge begins.
3. The gas valve is energized and the igniter will spark
for up to 10 seconds. If a flame is not sensed during
the trial for ignition, two additional tries will be
attempted before going into lockout for one hour.
4. When a flame is sensed, sparking stops immediately.
The gas valve and combustion blower remain
energized.
5. Ignition
4:1 Electronic Modulation - The burner will light at
100% fire and remain there for 10 seconds. The main
burner gas valve will then modulate from 100% down
to a minimum of 25%, as needed. The combustion
blower will change between high and low speed
to maintain acceptable combustion airflow. If the
high speed pressure switch does not pull in when
required, the furnace will lock out.
High Turndown Electronic Modulation - The
furnace controller will ignite the necessary
manifold(s) at 100% for 10 seconds. The main burner
gas valves will then modulate from 100% down to
a minimum of 25% as needed. The combustion
blower will change between high and low speed to
maintain acceptable combustion airflow. If less heat
is needed, a manifold section will be turned off. Each
time a manifold section is initialized, the manifold
section will ignite at 100%.
6. The ignition control constantly monitors the call for
heat, the pressure switch and the burner flame to
assure proper operation.
7. When the unit or furnace controls are satisfied,
the main gas valve is then de-energized and the
combustion blower shuts off following a 30 second
post-purge period.
Recovery from Lockout
If the furnace goes into lockout, the ignition control will
automatically reset after one hour if the thermostat is still
calling for heat. If needed, a manual reset can be
accomplished by either shutting off the power or turning
off the call for heat (turn off the thermostat) for a period
of five seconds.
Performance Data
Supply Air Temperature Rise
20°F 30°F 40°F 50°F 60°F 70°F 80°F 90°F 100°F
Model
Input
(BTU/hr)
CFM
50 50,000 1852 1235 926 741 617 529 463 412 370
75 75,000 2778 1852 1389 1111 926 794 694 617 556
100 100,000 3704 2469 1852 1481 1235 1058 926 823 741
125 125,000 4630 3086 2315 1852 1543 1323 1157 1029 926
150 150,000 5556 3704 2778 2222 1852 1587 1389 1235 1111
175 175,000 6481 4321 3241 2593 2160 1852 1620 1440 1296
200 200,000 7407 4938 3704 2963 2469 2116 1852 1646 1481
225 225,000 8333 5556 4167 3333 2778 2381 2083 1852 1667
250 250,000 9259 6173 4630 3704 3086 2646 2315 2058 1852
275 275,000 10185 6790 5093 4074 3395 2910 2546 2263 2037
300 300,000 11111 7407 5556 4444 3704 3175 2778 2469 2222
325 325,000 12037 8025 6019 4815 4012 3439 3009 2675 2407
350 350,000
12963 8642 6481 5185 4321 3704 3241 2881 2593
400 400,000
14815 9877 7407 5926 4938 4233 3704 3292 2963