Cleaning a Furnace Flame Sensor
If your furnace flame sensor has become dirty with build up, the furnace won't function properly. Keeping the sensor clean is simple and requires just a few tools when you follow these easy steps.
Step 1 - Turn Off the Power
Before you start working on the furnace, you need to cut the power. Turn it off at the breaker box for the safest operation.
Step 2 - Locate and Remove the Sensor
The sensor is typically attached towards the rear of the furnace. Look for a rod that is placed in the path of the burner. The sensor is held in place with one or two sheet metal screws attached to a bracket. Remove the screws to drop the sensor box from the bracket. Not all models will allow you to remove the sensor. You can still clean it; doing so will just require you to work in an odd position to access it.
Step 3 - Clean
Many people suggest you use sandpaper. While this is acceptable, it can damage the sensor. Emery cloth can be found at any hardware supply store and is a much better option. Gently scrub the sensor surface to remove any build up.
Step 4 - Reattach
Reattach the sensor and turn the furnace back on. Check your sensor regularly for subsequent build up.