Noticing a burning smell coming from your vents or furnace when your heating system is running isn’t always something you need to worry about. Nonetheless, there are many times when a burning smell is a sign of a potentially serious issue. This makes it essential that you immediately try to identify the source of the burning smell so that you know whether you need to have your furnace repaired. With that in mind, here are the main reasons a furnace will produce a burning smell and how you can identify them.
Your furnace will typically always produce a strong burning smell when you turn it on for the first time each winter. This is perfectly normal and nothing you need to worry about as long as the smell goes away within an hour or two. In this case, what you are smelling is all the dust inside the furnace burning away.
Any time a furnace sits idle for a prolonged period, dust and debris will slowly accumulate on the heat exchanger, burners, and other components. Once you finally turn your heating system back on, all the dust will quickly burn away and produce a strong burning smell that circulates throughout the ductwork and out of all your vents.
If you notice a burning smell when your furnace has been in regular use, you will want to immediately start looking for signs to help you identify where the smell is coming from. This is also the case if you have just started your furnace for the first time this winter and the smell doesn’t go away within a couple of hours.
Nothing shcanet inside your furnace’s combustion chamber. Nonetheless, we occasionally encounter situations where a plastic bottle cap, children’s toy, or some other foreign object has gotten inside the furnace and then starts burning whenever the furnace runs. You can easily check for this by inspecting the area around the furnace burners to ensure there aren’t any foreign objects inside. If you do see anything, you will want to make sure to leave your furnace shut off to allow it to cool down before you try to remove the object fully.
Overheating Blower Motor
If the blower motor or its components overheat, it can also produce a strong burning smell that circulates throughout the building. A clogged air filter is the most common cause of overheating, as it restricts how much air the blower can draw in. This forces the blower to work harder and can put enough stress on it that it quickly begins to overheat and start smoking. If the air filter is clogged and very little cold air is being drawn into the system, heat will quickly build up inside the furnace, potentially leading to the furnace and blower overheating.
Damaged Electrical Wiring
Your furnace has a built-in safety mechanism known as a limit switch designed to automatically shut down the heating system if the furnace or blower starts to overheat. This is important as all that heat can cause the insulation around the electrical wires to begin to melt and create a major risk of an electrical fire. Unfortunately, there are situations where the limit switch can fail and prevent the furnace from shutting down when it overheats. Therefore, if you ever notice an electrical burning smell, you will want to immediately shut off your heating as this indicates that the wiring is damaged and thus creating a fire risk.
A flame rollout is when the flames inside the furnace grow so large that they escape the confines of the combustion chamber. This issue occurs because inflammable combustion fumes remain trapped inside the combustion chamber and heat exchanger, which starves the flames of oxygen and can almost instantly cause them to grow much bigger. This typically happens because the heat exchanger or exhaust flue is clogged, preventing the fumes from being vented outside.
A flame rollout will often singe the exterior of your furnace and potentially cause the entire unit to become so hot that it could ignite anything near it. A rollout can also allow the flames and heat to reach parts of the furnace that aren’t meant to be exposed to such high temperatures, which can cause things to start to smoke and produce a noticeable burning smell.
If you notice any singeing or discoloration of your furnace, you should shut it off until you can inspect it. Otherwise, there is a risk that all that heat could crack the heat exchanger and allow carbon monoxide to start leaking out into your home.
At Smith & Willis Heating & Air Conditioning, our technicians can quickly diagnose any burning smells and determine the best way to fix the issue. We repair all models and types of furnaces, and our technicians also specialize in heating and cooling maintenance and installation. If you need any HVAC or indoor air quality service in Commerce City, call us today.