Operating instructions
pressure is outside this range. Personal injury or unit damage
may result.
Unsafe operation of the unit may result if manifold pressure
is outside this range. Serious injury , death or unit damage
may result.
3. Replace cover screw cap on gas valve.
4. Turn off gas supply to unit. Remove manometer from pressure
tap and replace pipe plug on gas valve. Turn on gas to unit and
check for leaks.
Measure Manifold Pressure (Propane Units)
The main burner orifices on a propane gas unit are sized for the
unit rated input when the manifold pressure reading matches the
level specified in Table 6.
Proceed as follows to adjust gas input on a propane gas unit:
1. Turn off gas to unit.
2. Remove pipe plug on manifold and connect manometer (See
Fig. 13).
3. Turn on gas to unit.
4. Remove cover screw over regulator adjustment screw on gas
valve.
5. Adjust regulator adjustment screw to the correct manifold
pressure, as specified in Table 6. Turn adjusting screw
clockwise to increase manifold pressure, or turn adjusting
screw counterclockwise to decrease manifold pressure.
6. Replace cover screw.
7. Turn off gas to unit. Remove manometer from pressure tap.
Replace pipe plug on gas valve, then turn on gas to unit. Check
for leaks.
CHECK BURNER FLAME
With burner access panel removed, observe the unit heating
operation. Watch the burner flames to see if they are light blue and
soft in appearance, and that the flames are approximately the same
for each burner. Propane will have blue flame with yellow tips
(See Fig. 14). Refer to the Maintenance section for information on
burner removal.
AIRFLOW AND TEMPERATURE RISE
The heating section for each size unit is designed and approved for
heating operation within the temperature-rise range stamped on the
unit rating plate.
Table 7 shows the approved temperature rise range for each
heating input, and the air delivery cfm at various temperature rises.
The heating operation airflow must produce a temperature rise that
falls within the approved range.
Refer to Indoor Airflow and Airflow Adjustments section to adjust
heating airflow when required.
HEATING SEQUENCE OF OPERATION
(See Fig. 15-17 and unit wiring label).
On a call for heating, terminal ‘‘W’’ of the thermostat is energized,
starting the induced-draft motor. When the hall-effect sensor on
the induced-draft motor senses that it has reached the required
speed, the burner sequence begins. This function is performed by
the integrated gas control (IGC). The evaporator-fan motor is
energized 45 sec. after flame is established. When the thermostat
is satisfied and ‘‘W’’ is deenergized, the burners stop firing and the
evaporator-fan motor shuts off after a 45-sec. time-off delay.
An LED (light-emitting diode) indicator is provided on the control
board to monitor operation. The control board is located by
removing the burner access panel. During normal operation, the
LED is continuously on (See Table 8 for error codes).
LIMIT SWITCHES
Normally closed limit switch (LS) completes the control circuit
through the thermostat R circuit. Should the leaving-air tempera-
ture rise above the maximum allowable temperature, the limit
switch opens and the R control circuit ‘‘breaks.’’ Any interruption
in the R control circuit instantly closes the gas valve and stops gas
flow to the burners and pilot. The blower motor continues to run
until LS resets.
When the air temperature at the limit switch drops to the
low-temperature setting of the limit switch, the switch closes and
completes the R control circuit. The electric-spark ignition system
cycles and the unit returns to normal heating operation.
Table 6—Heating Inputs
HEATING
INPUT
(BTUH)*
NUMBER
OF
ORIFICES
GAS SUPPLY PRESSURE
(IN. WG)
MANIFOLD
PRESSURE
(IN. WG)
Natural Propane†
Min Max Min Max Natural Propane†
40,000 2 4.0 13.0 4.0 13.0 3.5 3.5
60,000 2 4.0 13.0 4.0 13.0 3.5 3.5
90,000 3 4.0 13.0 4.0 13.0 3.5 3.4
115,000 3 4.0 13.0 4.0 13.0 3.5 3.7
130,000 3 4.0 13.0 4.0 13.0 3.5 3.5
* When a unit is converted to propane, different size orifices must be used. See separate, natural-to-propane conversion kit instructions.
† Based on altitudes from sea level to 2000 ft above sea level. For altitudes above 2000 ft, reduce input rating 4 percent for each additional 1000 ft above sea level.
In Canada, from 2000 ft above sea level to 4500 ft above sea level, derate the unit 10 percent.
Table 8—LED Indications
ERROR CODE LED INDICATION
Normal Operation On
Hardware Failure Off
Fan On/Off Delay Modified 1 Flash
Limit Switch Fault 2 Flashes
Flame Sense Fault 3 Flashes
Four Consecutive Limit Switch Faults 4 Flashes
Ignition Lockout Fault 5 Flashes
Induced-Draft Motor Fault 6 Flashes
Rollout Switch Fault 7 Flashes
Internal Control Fault 8 Flashes
Temporary lock-out (1 hr) 9 Flashes
NOTES:
1. There is a 3-sec. pause between error code displays.
2. If more than one error code exists, all applicable error codes will be
displayed in numerical sequence
3. This chart is on the wiring diagram located inside the burner access panel.
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