Furnace Pilot Light Adjustments

Lighting the Pilot Light

It is always important to read the furnace instruction manual before attempting to light the pilot burner. The basic procedure for lighting a pilot can be done in these four steps:

1. Turn the room themostat to its lowest setting to ensure it wont go on
2. Shut off the main gas supply to the main burner and the pilot burner
3. Allow at least 5 minutes to go by so the unburned gas can vent
4. Light the pilot burner in accordance with the furnace instructions

Venting the unburned gas is the most important step here.  This is especially true for LP gas because it is heavier than air and will not vent upward on its own. Every precaution should be taken to make sure the appliance is properly venting the unburned gas. Appliance and pilot burner instruction are very detailed for their lighting process of their equipment.  The development of various types of combination gas controls has simplified the lighting procedure and increased the safety factor.

Pilot-Pressure Switch

The pilot-pressure switch operates on the same principle as the gas pressure switch used in the manifold of the gas-fired furnace or boiler. Its function is to prevent the premature failure of the spark igniter or glow coil should a prolonged gas interruption occur while the thermostat is calling for heat.  The pilot-pressure switch is installed in the pilot gas line between the pilot light and regulator.  Installing a pilot switch requires that the pilot gas line be disconnected downstream from the pilot gas regulator. The gas line is then connected tot he pilot-pressure switch by cutting the existing tubing to the regulator and connecting into the tee provided for switch mounting

Pilot Flame Adjustment

The pilot flame must be adjusted for proper color and size. Appliance manufacturers refer to this procedure as pilot flame adjustment or gas adjustment as you are really adjusting the amount of gas that flows to your furnace pilot flame.  The furnace manufacturer will provide instructions for making your flame adjustment. On combination gas valves, this involves the removal of the pilot adjustment cap and turning the adjustment screw until the desired flame characteristics are obtained. The best pilot flame is a steady, nonblowing blue flame that envelopes the upper 1/2 inch of the thermocouple or generator.

If you do not feel comfortable making these adjustments, contact a local HVAC contractor to help with your pilot light.