Adjusting the Pilot Light in a Central Heating System

  • 1 hours
  • Beginner
  • 0-30
What You'll Need
Long matches or butane lighter

As tiny as your central heating system pilot light is, its importance to the operation of the system is huge. Without its functioning properly, your furnace won't light and therefore, won't heat. It is simple to know if your pilot light is working properly. If it is not working as it should, it could be because its flame is not properly adjusted. Once you've determined that your pilot light is not working properly you can often fix it by simply adjusting its flame. To adjust your pilot light, just follow the 5 steps below.

Step 1 – Inspect your System Pilot Light

Remove the panel from your furnace. You may need to remove screws that hold the panel in place. If light is dim near your furnace, you'll need to either turn on a light near your furnace or plug in a work light. Once you have your light ready, remove the screws attaching the panel to the furnace and set them aside where you'll find them when you're ready to replace the cover.

Step 2 – Determine if the Pilot Light Is lit

Look inside the furnace to see if the pilot light is lit. It is a tiny blue flame no higher than ½". If it is lighted you should have no trouble spotting it at once. If you see a larger gas flame in the burner part of the furnace you can usually assume the pilot is working, since the gas in the burner is nearly always ignited by the lighted pilot light. If the pilot is not lighted, it may be because the flame has been extinguished, or because your thermocouple is not working properly.

Step 3 – Inspect the Pilot Light

You furnace may, or may not, have a cap over the pilot light that covers an adjustment screw. If it has a cap, remove the cap and locate the adjustment screw. This screw adjusts the flame size on your pilot light. If the flame is too small, it is likely to be extinguished by a draft or movement of air around it. The flame, if it is working properly, should be blue at the center and bottom and slightly yellow at the tip of the flame. You should also see that the flame envelopes the thermocouple bulb, preferably ½". If the flame has more than a slight yellow edge a its peak this is an indication that gas-oxygen proportion is too much air and not enough gas.

Step 4 – Adjust the Pilot screw

Use your screwdriver to turn the adjustment screw clockwise to make the pilot light flame smaller and less yellow. Turn the screw counter clockwise to make the flame larger and more yellow. If you are unable to reduce the yellow color in the flame by turning the screw, this could mean there could be some sort of obstruction in your fuel line. In this case, you should call an experienced HVAC technician to service your furnace.

Step 5 – Replace the Screw Cap and Furnace Panel.

When you have completed your adjustments, replace the pilot adjustment cap and furnace panel.