Heater Smells Like Burning: Top 11 Causes and Solutions

After sitting dormant for months, it is common for heaters to encounter problems, including unpleasant odor, especially when turned on for the first time. However, that shouldn’t last long; if the burning smell from the heater lingers, consider this a cause for alarm. It is your sign to get to the bottom of the reason, as the burning smell might be potentially dangerous.

There can be several reasons why the heater smells like burning. Some might require simple fixes, while others can be complex and require professional assistance. This guide will provide an overview of what to look out for and how to address the issue.

1. Dust on the Furnace

Does your heater smell like burning plastic? Homeowners residing in regions with changing seasons might bring out their heater after a very long time. In this case, the chances of dust buildup on your furnace are high. Dust accumulating on a furnace’s heating elements can act as an insulator, preventing the furnace from properly heating. In addition, when the furnace is running, the dust on the heating elements can start to smolder and emit a plastic-burning smell. This is a sign that the furnace needs to be serviced and cleaned.

How to Resolve This?

First of all, don’t worry; this is not concerning and can be dealt with at home. Next, inspect your unit for dust buildup without touching it. The smell should go away by itself when the dust has all burned off. Finally, run the heater for a few minutes and notice if the odor subsides. If it lingers or worsens with time, you might have misdiagnosed the cause of the burning smell and should call a technician.

2. Debris Trapped in the Heating System

While your heating system wasn’t in use, it’s possible that some kind of object accidentally fell into your HVAC unit or the system’s ductwork, causing airflow problems. This causes a burning smell from the central heating. If you have central heating with various vents throughout your home, see if you can pinpoint the burning smell in one specific room. If you’re successful, there might be something trapped inside your vent that’s causing the odor.

How to Resolve This?

If your heater smells like burning, identify the room it is coming from and try reaching the vent. If you can, open it or peek inside. You might be able to spot a toy, a part of the heating system, or another object trapped inside. Try safely removing the thing from your vent and then wait to see if the burning smell from the heater continues. If you can’t safely remove it or the smell persists, call in an HVAC professional to assist.

3. Dirty Furnace Filters or Air Vents

Gas furnace maintenance is essential in helping you prevent a burning smell emanating from your heater. For example, if your furnace has dirty filters or the air vents in your system are clogged, the buildup could result in an unpleasant, musty smell.

How to Resolve This?

Understand that there are different types of filters that are used in an HVAC system. Only once you know what you are dealing with, get on with the maintenance. Clean the filter inside your unit and try running it again. If a newly cleaned filter doesn’t eliminate the odor, call an HVAC professional to inspect your unit and ductwork.

4. Faulty Electrical Wiring

Faulty electrical wiring is a major cause of the burning smell from heaters. It is possible for the wiring to be damaged over time due to age or wear and tear. If the wiring is damaged, it can cause arcing or sparking, resulting in a burning smell. In addition, if the heater is not serviced regularly, the wiring can become loose or frayed, resulting in a pungent odor.

Other reasons causing the electrical wiring to default include an overheating blower motor or a cracked heat exchanger. This choking smell can be hazardous to health and cause respiratory issues. Hence, this should be taken care of immediately.

How to Resolve This?

If your heater smells like burning because of electrical wires burning, it is a relatively more serious problem. In this case, your system should shut off automatically; if it doesn’t, turn it off immediately and contact a professional. Do not try to handle it yourself, as it can be potentially very dangerous.

5. Damaged Oil filters

If you have an oil furnace, dirty or damaged filters can cause a burning smell. If your heater’s oil filter is clogged, it can cause the heating unit to run inefficiently or not work at all. Other problems that can occur with a heater’s oil filter include a bad seal, a loose connection, or a damaged filter.

How to Resolve This?

You will have to replace the oil filters and check if the odor is gone. You need to change these every three months. If the issue persists, call an HVAC professional. In addition, make sure your home is well-ventilated to minimize the chances of any serious health issues.

6. Fan Motor Overheating

Overheating the fan motor will undoubtedly emanate a burning smell similar to gunpowder. The most common cause of fan overheating is when too much heat from the motor persists for too long and becomes frequent. This can cause a fan to overwork and blow excessive air, which can lead to the heater becoming hot. It can also be because of a fried circuit board.

How to Resolve This?

You can do a few things to help prevent overheating and the burning smell in your heater. First, it is important to know why the fan motor is overheated. Overheating can lead to the fan motor becoming hot and sparking. If a used fan causes overheating, remove the motor’s hot end cover and leave it open to cool it down. Once the overheating settles, you can inspect the unit for any fault in the wiring, or debris accumulation or call a technician if you can’t figure out the problem.

7. Damaged Heaters or Furnaces

Damaged heaters or furnaces can be why your heater smells like burning as the wires or other components become overheated. This can happen when a component fails or a wiring issue causes too much electricity to flow to the element. In either case, the heat created can cause a burning smell and should be inspected and repaired immediately. Forgoing maintenance is another major cause of the malfunctioning of the furnace.

How to Resolve This?

In this case, you might be able to repair/replace the part(s) of the heater that has been damaged. However, if you fail to catch it in time, you might even have to replace the heating system altogether. For this, the best way is to consult an HVAC technician to gauge the extent of the damage that has been caused.

8. Mold Growth

If you are experiencing a musty smell from the HVAC system, it is probably because of mold growth. Mold can form in the air ducts, filter, or inside the heater itself. The musty smell is caused by the mold releasing spores into the air. If not treated, the mold can spread, causing health risks for those living in the home.

How to Resolve This?

Follow the steps below to clean up mold from your heaters:

1. Wear a mask and gloves. Make sure to cover your mouth and nose and wear gloves when cleaning mold from a heater.
2. Make sure to turn off the power to the heater before attempting to clean it.
3. Vacuum the area to remove any visible mold spores from the heater.
4. Use a damp cloth and mild detergent to clean the area where the mold is present.
5. Use a fan or dehumidifier to dry the area completely.
6. Remove the filter from the heater and clean it with mild detergent and warm water.
7. Use an air purifier to treat the air in the room and a dehumidifier to reduce humidity levels and prevent mold growth in the future.

Related: Is Mold in Your Air Conditioner Dangerous?

9. Broken Wastewater Line

If the broken wastewater line is connected to the heater, then sewage or wastewater may enter the heater, leading to your heater smelling like burning. This can happen if the wastewater line is leaking or a blockage in the line is causing it to back up.

How to Resolve This?

When your heater smells like burning, and this is the case, the wastewater should be cleaned up and repaired as soon as possible to prevent further damage.

10. Natural Gas Leak

The presence of sulfur in natural gas causes the smell of rotten eggs. The sulfur is added to the gas as an additive to make detecting any potential gas leaks easier. The rotten egg smell is an indication that there may be a leak in the gas line or heater and should be checked by a professional.

How to Resolve This?

Do not try to fix a gas leak yourself. Instead, always seek help from an HVAC technician. Here is what you should do in case of a gas leak:

1. Turn off the gas at the source.
2. Open the windows and doors to ventilate the area.
3. Call a technician to inspect the heater and repair the leak.
4. Have the technician check for carbon monoxide levels in the space.
5. If the carbon monoxide levels are high, evacuate the area immediately and seek medical attention if necessary.

11. Pest Infestation

Pests such as mice, rats, and other rodents can cause burning smells from a heater if they become trapped inside the unit. They can chew through electrical wires, which can create a short circuit, leading to burning smells. Additionally, their nesting materials can also create a burning smell when they are heated up by the heater.

How to Resolve This?

1. Inspect your heater regularly for signs of pests. Check for droppings, nests, and other signs of infestation.
2. Vacuum the area around the heater thoroughly to remove any droppings or other debris.
3. Seal any cracks or holes in the wall or floor around the heater to prevent further infestations.
4. Place traps or bait stations in areas where pests are likely to gather.
5. Use a pesticide spray around the area to help kill any remaining pests.

Related: Heater Sickness – Why Your Heating System May Be Triggering Your Allergy

Prevention is Better Than Cure

Scheduled regular maintenance is the answer to so many of your HVAC-related problems. Ensure you have a yearly tune-up with an HVAC professional, especially before the heaters are rolled out for the winter. Regularly cleaning the furnace can prevent dust and debris buildup, eliminating the probability of your heater emitting a burning smell. Furthermore, in order for your heater to run the entire season smoothly, it is recommended that you get the filters changed every three months.

With regular maintenance, not only will you be able to keep the heater clean, but you will also be able to detect any serious electrical issues in time. This is essential for your safety as well as keeping the repair costs at bay. While this is not a foolproof way to get rid of the unpleasant, strange, burning smells, it is your safest bet and the best way to avoid them in the future.