How to Clean a Furnace Flame Sensor: 5 Steps & Tips
There’s no doubt about it: furnaces are one of the most important appliances in our homes. They help keep us warm in the winter. Furnaces are made up of a variety of parts and components that are engineered to ignite natural gas to create warm air. Although the heat exchanger and gas burners in your furnace are critical to produce heat energy, the most important part in a furnace is the flame sensor. If you are encountering issues with your furnace, this is a sign of a dirty flame sensor. To help you restore the operation of your furnace on a cold day, we have compiled a list of steps to follow when you are cleaning your flame sensor.
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How to Sanitize a Furnace Flame Sensor
Knowing how to clean the flame sensor is an important part of keeping your furnace functioning properly in the winter season. If you don’t clean the flame sensor once a year, the furnace in your home can fail on a cold day or night. To prevent the negative consequences of becoming trapped in a blizzard, follow these steps to remove and sanitize your flame sensor.
1.) Deactivate the Furnace
Before you start to clean the furnace flame sensor, make sure that the power is off. Inspect the area near your furnace to find the power switch. The switch will resemble a miniature toggle on your furnace. If you can’t find it, shut the furnace down from the circuit-breaker box in your garage. Next, make sure to shut off the gas to the furnace prior to cleaning the flame sensor. For your safety, it is important that you both turn off the furnace and shut off the gas. Remember: turning off the thermostat does not deactivate the power to the furnace.
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2.) Detach the Flame Sensor
Prior to cleaning the flame sensor, you will need to remove the screws to detach the sensor from the furnace. Once the screws are removed, the flame sensor will slide out of the furnace. To properly remove it, unscrew the ¼” hex head screw it is mounted by. Remove it with care. Depending on the furnace you have, you might need to detach a wire from the flame sensor.
3.) Sanitize the Flame Sensor
To clean the flame sensor, gently rub the metal rod with light grit sandpaper. Do not use sandpaper on any other component in your furnace. This is to get rid of the buildup on the sensor. Next, take a paper towel to remove excess dirt from the flame sensor.
4.) Replace and Reconnect the Sensor
After you have cleaned the flame sensor, reconnect the wire if you took it off and reconnect the flame sensor on the burner assembly with the ¼” screw. Screw it back in and put the doors back on. Once everything is securely fastened, turn the furnace back on.
5.) Test the Furnace
When you turn the furnace back on, it might take a couple of seconds to start the heating cycle. The fan may activate and operate for a couple of seconds before the natural gas is ignited. It is normal for the furnace to operate for a small amount of time before the gas is ignited in the burners. The delay is caused by a series of tests that are being performed by the furnace to confirm everything is working properly. When the furnace is assembled and the flame sensor is clean, the heating system should operate normally.
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How a Flame Sensor Operates
The furnace’s flame sensor is a small metal rod with a base that conducts an electric current. When the gas valve opens at the beginning of the heating process, an electrical current is distributed to the flame sensor to detect whether or not a flame is present. The pilot light or electric igniter in a furnace is designed to produce a miniature flame that is used to ignite incoming natural gas before it arrives at the heat exchanger.
Once the flame sensor detects a flame, the natural gas will be circulated to the gas burners and heat exchanger. If the flame sensor needs to be cleaned and cannot detect a flame within 10 seconds of operation, it will disburse an electrical signal to turn the furnace off to prevent a toxic gas leak. This cycle repeats a couple of times.
Depending on the model of your furnace, the flame sensor will perform a total of two tests to detect and monitor the flame. If the flame sensor cannot sense the flame at the end of the second test, the furnace may be permanently shut down and you will be required to clean the flame sensor to restore the system.
Why It’s Important to Clean Your Furnace Flame Sensor
Do you hear your furnace starting and shutting off every 5 minutes? Does this happen a variety of times, and you still receive no heat in your home? The likely culprit is a dirty furnace flame sensor that needs to be cleaned by a certified technician. When the furnace doesn’t turn on, many homeowners might look to professionals to assess the situation and remedy it. However, cleaning your flame sensor before calling a licensed technician could save you money in the long run. In some cases, cleaning your flame sensor is what gets your furnace up and running again.
Differences Between Bi-Metallic Strip and Optical Reader Flame Sensors
Bi-Metallic Strip Flame Sensors
There are two main types of flame sensors: a bi-metallic strip and an optical reader. Bi-metallic strip flame sensors generate a small amount of voltage when it comes into contact with heat. The greater the heat, the higher the voltage. Of the two types of flame sensors, bi-metallic strip flame sensors are common because they are inexpensive, easy to clean, and highly accurate.
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Optical Reader Flame Sensors
Optical readers are used for large industrial furnaces and boilers. An optical reader flame sensor features a higher voltage in comparison to bi-metallic strip sensors. They use a photocell that will generate a voltage from the light source. The brighter the light, the larger the voltage. Optical reader flame sensors are especially sensitive to dust or debris, which means they need to get cleaned often to remain effective. Although optical reader and bi-metallic strip flame sensors produce a voltage in the presence of a flame, an optical reader is utilized in industrial applications while a bi-metallic sensor is used in homes.
Heating & Furnace Repair Services
Keep your heating system in tip-top condition with our innovative heating repair services. Our experienced professionals will help you clean your flame sensor and offer dependable furnace repair or furnace tune-up services to homes in New Jersey. In addition, our team of certified technicians offers furnace installation and replacement services. Choosing to delay a furnace maintenance service can put your family at risk of dealing with the negative consequences of a gas leak or dangerous temperatures. Give our staff a call by phone at (732) 201-3305 to create an emergency heating appointment for your furnace.
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