During the cold winter months, very few things can be worse than the furnace going out. It works quietly in the background of our lives–until suddenly the house starts getting colder and we realize just how vital this system can be. However, most often, furnaces don’t fail catastrophically. In fact, sometimes the fix to most common furnace issues are inexpensive, can be fixed with very few tools, and you can even do it yourself.
Here is a list of the most common components that lead to furnace failure. Some of them are simple; others are complex. But one thing is certain: most of these can be diagnosed with routine maintenance. Staying on top of your annual maintenance can ensure that small problems are corrected before they become big ones, and small issues can be remedied before the furnace fails. Here are our top 5 reasons a furnace fails:
1. DIRTY FLAME SENSOR
The flame sensor is a safety feature that allows your furnace to know whether the flame in your furnace is consistent and that there are no problems with the fuel source. The flame sensor tells your furnace to shut off if it doesn’t sense a flame. This way, you don’t have gas spilling into your house that isn’t being burned. The flame sensor is a metal bar that the flame burns onto directly. It can get dirty over time from soot, dust, or other elements in your house. If your furnace seems to be kicking off and on, putting out a little heat but not being consistent, it could be that you have a dirty flame sensor.
Flame sensors can be cleaned relatively easily with few tools. However, be careful when cleaning your sensors. It is a delicate part that takes some care to clean. Also, make sure you’re actually looking at and cleaning the correct part.
→ Click here for a video explaining where the flame sensor is and how to clean it
Sometimes flame sensors fail as well. They are meant to sense electricity from the flame the furnace produces, if the sensor shorts out or goes bad, it may also need to be replaced. Stray voltage in the house can cause a flame sensor to malfunction, wear out, and eventually break. Here is a video explaining how to replace a flame sensor if it has failed:
→ Click here for a video explaining how to replace a flame sensor if it has failed
2. IGNITER
Due to normal wear and tear, often the igniter will go out. This is a component that endures constant expansion and contraction and really high heat, failure is pretty common. They are also susceptible to power surges, which can also cause them to fail.
The average furnace turns on 4-5 times per hour, that means over the course of a season, the igniter is undergoing a lot of stress. We recommend getting a diagnosis from a licensed HVAC technician to know that the igniter is the culprit first before attempting to replace it yourself.
3. INDUCER MOTOR
The inducer motor draws air through the combustion area, through the heat exchanger, and out the exhaust pipe. It has an essential role to play in the overall function of your furnace. This is the first thing to activate when the furnace kicks on. This motor makes sure the pathways are clear in your system and also ensures adequate airflow.
There are many reasons why this motor will fail. For one, there are many bearings in the motor that make it run and these bearings can go out for myriad reasons. Oftentimes birds, for example, can get into the motor, causing big problems. But really, our techs have seen all kinds of things in the motor from golf balls to racoons and squirrels. The inducer motor is only used in the winter when the house needs to be heated so all kinds of critters and things can get in there during the summer that you don’t know about until you run the furnace. While new codes and flue styles will keep most things out, blockages can still occur.
If you hear a high-pitched squeal, this could be the bearings or could be the housing the motor is in–indicating trouble with the inducer motor.
Keeping your furnace clean will go a long way in ensuring you don’t have trouble in the winter.
→ Click here for a video explaining where the flame sensor is and how to clean it
4. BLOWER MOTOR
The blower motor is the big motor that forces air throughout the house. When it comes to this motor, there are myriad things that could go wrong: the capacitor, the motor itself–both the bearings or the electrical components. The capacitor going out is fairly common. It most commonly goes out because of wear and tear on the motor. A dirty motor can also cause imbalances in the fan, which will cause the bearings to wear and make strange noises. Again, this is a part that will benefit greatly from keeping the furnace clean.
Unfortunately, this part is expensive to replace. Routine maintenance is your best strategy for making sure you don’t have a costly blower motor repair down the road! Be sure to clean the furnace frequently and stay on top of filter replacements so you can protect the blower motor and its components.
→ Click here for a video showing how to clean the blower motor on your furnace
→ Click here for a video explaining how to test the run capacitor for your furnace blower fan
5. CIRCUIT BOARD
A failed circuit board is another costly repair. As the “brains” of the furnace, or the computer that tells the furnace how to function, it’s incredibly vital. However, many things can impair its functionality. Voltages and surges can affect the function of the circuit board. Dirt can also cause a circuit board to fail–as dirt and dust build up and cause an insulated layer on the board, creating heat which will cause the board to overheat and burn out.
Additionally, the presence of water could also cause the circuit board to short. A leaking humidifier could be a culprit to a failed circuit board, as could any other water, condensation, or leaks. Water wreaks havoc on the copper components and causes them to fail. So make sure to keep any water sources or leaks away from the furnace!
In all cases, refer to your owner’s manual to see your manufacturer’s recommendations for annual maintenance. Most furnaces get neglected; yet, the best way to make sure your furnace continues to run effectively for years to come is through regular maintenance and cleaning. Additionally, changing the furnace filter is the most important step you can take to ensuring the continued health of your unit.
For additional information on this topic, watch this episode of our podcast – 043: Most Common Furnace Problems
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