25
Fig. 38 — Spark Adjustment (04-06)
Gas Valve
All three-phase models (except Low NOx) are equipped with 2-
stage gas valves. Single-phase models and all Low NOx models
are equipped with single-stage gas valves. See Fig. 40 for loca-
tions of adjustment screws and features on the gas valves.
Check Unit Operation and Make Necessary Adjustments
NOTE: Gas supply pressure at gas valve inlet must be within
specified ranges for fuel type and unit size. See Tables 4-7.
1. Remove manifold pressure tap plug from manifold and con-
nect pressure gage or manometer. (See Fig. 36.)
2. Turn on electrical supply.
3. Turn on unit main gas valve.
4. Set room thermostat to call for heat. If unit has two-stage gas
valve, verify high-stage heat operation before attempting to
adjust manifold pressure.
5. When main burners ignite, check all fittings, manifold, and
orifices for leaks.
6. Adjust high-stage pressure to specified setting by turning the
plastic adjustment screw clockwise to increase pressure,
counter-clockwise to decrease pressure.
7. For two-stage gas valves, set room thermostat to call for low-
stage heat. Adjust low-stage pressure to specified setting.
8. Replace regulator cover screw(s) when finished.
9. With burner access panel removed, observe unit heating oper-
ation in both high stage and low stage operation if so
equipped. Observe burner flames to see if they are blue in
appearance, and that the flames are approximately the same
for each burner.
10. Turn off unit, remove pressure manometer and replace the
1
/
8
-in. pipe fitting on the gas manifold. (See Fig. 35.)
LIMIT SWITCH
Remove blower access panel. Limit switch is located on the fan
deck. See Fig. 31.
Burner Ignition
Unit is equipped with a direct spark ignition 100% lockout system.
Integrated Gas Unit Controller (IGC) is located in the control box.
See Fig. 37. The IGC contains a self-diagnostic LED (light-emit-
ting diode). A single LED (see Fig. 41 and Table 9) on the IGC
72,000 BTUH INPUT AND 60,000 BTUH INPUT
115,000 BTUH INPUT,
150,000 BTUH INPUT,
90,000BTUH INPUT AND
120,000 BTUH INPUT
LOW HEAT
MEDIUM AND HIGH HEAT
IMPORTANT: Leak check all gas connections including the
main service connection, gas valve, gas spuds, and manifold
pipe plug. All leaks must be repaired before firing unit.
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