1.5.3Main Burner System
For the burners to work the gas supply valve must be open and the main power switch must be on. The main burner receives gas from the main gas supply through the thermostatically controlled valve. When the thermostat is turned up the gas control valve opens. If you have a pilot light system, the pilot will ignite the burners. The electronic ignition system will create a spark to ignite the gas. After the burner system is operating, perform the burner adjustments in the following procedure. Figure
The tubes and baffles are badly carbonized. Check vent and adjust if necessary. Check for heat tube or flue 
blockage.
INSUFFICIENT FLOW
Have gas company check incoming gas pressure. Adjust manifold pressure as described in 1.5.3.2.
The flame seems to "lift off" the face of the burner.
To correct adjust main burner as described in 
1.5.3.2.
EXCESSIVE FLOW
A soft, steady blue flame should enter the heat tube without touching the front outside rim of the tube.
INSUFFICIENT GAS PRESSURE | NORMAL FLOW |