13
Burner Flames
Prior to completing the start-up, check the appearance of the main burner flame. See Figures below for flame
characteristics of properly adjusted Natural gas systems.
Figure 11A
Figure 11B
1. The burner flame should be predominately blue in color and well defined and centered at the tube entry as
shown in Figures above. Distorted flame or yellow tipping of natural gas flame, or a long yellow flame on
propane, may be caused by lint and dirt accumulation inside burner or at burner ports, at air inlet between
burner and manifold pipe, or debris in the main burner orifice. Soft brush or vacuum clean affected areas.
2. Poorly defined, substantially yellow flames, or flames that appear lazy, indicate poor air supply to burners or
excessive burner input. Verify gas supply type and manifold pressure with rating plate.
3. Poor air supply can be caused by obstructions or blockage in heat exchanger tubes or vent discharge pipe.
Inspect and clean as necessary by to eliminate blockage. Vacuum any dirt or loose debris. Clean heat
exchanger tubes with stiff brush. Poor flame characteristics can also be caused by undersized combustion
air openings or flue gas recirculation into combustion air supply. Increase air opening size or re-direct flue
products to prevent re-circulation.
4. Reduced air delivery can also be the result of fan blade slippage, dirt accumulation the fan blade or low
voltage to draft inducer motor. Inspect draft fan assembly and be sure fan blade is secure to motor shaft.
Check line voltage to heater.
Shutdown
1. Set thermostat or controller to lowest setting.
2. Turn off electrical supply to unit at disconnect switch.
3. Turn off manual gas supply.
4. Disconnect manifold and inlet pressure taps and re-install pipe plugs
5. Replace vestibule access panel or close door.
Normal Operation
1. Turn on electrical supply to unit at disconnect switch
2. Turn on manual gas supply
3. Set Thermostat or Temperature controller to desired temperature.
4.
Information outlining the normal Sequence of Operation and Wiring Diagram for the control system supplied
with the furnace model is enclosed with this instruction
.
Burner Flame @ Start-up
1.2” w.c. Manifold
Pressure Draft Inducer
– High Speed
Burner Flame @ High Fire
3.5” w.c. Manifold
Pressure Draft Inducer
– High Speed