A heating system is a vital appliance in our modern homes to maintain our home comfort when the weather turns cold outdoors. But, this is a complex appliance and like any system, there are things that can go wrong. The best way to keep your furnace in great shape is to schedule some regular essential maintenance. This should happen annually before the start of the heating season. If you have a furnace, it may have a degraded level of performance and poor energy efficiency. Some people turn on their furnaces and notice a pronounced burning smell. In this article, we will explain why this happens and what you can do about it.
Prolonged Periods of Disuse
After a prolonged period of disuse, it’s pretty common to notice some weird odors when you turn on a furnace. If you have a vacation home or cabin and you didn’t get the chance to use it during pandemic lockdowns, it may be a little neglected. It’s important to note that many of these initial odors are not dangerous. They may dissipate after the furnace has been on for a while as dust and other debris burn away. But, it’s also important to recognize that certain smells and ongoing odors can be a sign that something is wrong. Complacency can have disastrous results and it’s worth carrying out your own investigation to determine the cause of the problem.
7 Furnace Smells Explained
In certain cases, you don’t need to be an HVAC technician to recognize the source of a bad furnace odor. Like many other systems, the type of smell can give you some helpful clues about the causes of the smell. Let’s take a closer look at seven bad furnace smells and what they may mean. They are:
1. The Smell of Burning Dust
The title of this article mentions a burning smell because that is the single most common odor that people notice when they turn on a furnace that has not been used for a while. This may seem like the worst possible smell, for good reasons most people associate the odor of burning with a fire. This is a natural reaction, but the smell of burning dust may be the least serious odor on our list. If you can smell burning dust, there is no need to panic because the cause is pretty innocuous. When a furnace has not been used for a while, a layer of dust accumulates on the surface. When the initial furnace ignition occurs and for the next few cycles this dust will burn off the surfaces. This is the source of the burning dust odor and after a short while, it will dissipate because the dust has been burned away entirely. If the odor does persist, the cause may be a dirty air filter that needs changing and the smell will usually disappear almost immediately. If the smell still lingers in your home, contact your local HVAC specialist for expert help and advice.
2. A Strong Chemical, Electrical, or Metallic Odor
The furnace is designed to shut off automatically if it overheats. But, this safety feature will not kick in if there is a crack in the heat exchanger or a fault in the blower motor. When these components overheat, they can release a powerful chemical, electrical or metallic odor. Many people describe this odor as a formaldehyde smell if you’re familiar with that from a high school biology class. The correct course of action is to turn off your furnace, inspect it for obvious damage and call an HVAC specialist to fix it for you.
3. A Gunpowder Smell
A strong cordite or gunpowder odor is usually caused by some kind of electrical fault. The source of the problem could be a burnt out fan motor or a fried circuit board. The components must be repaired or replaced to restore normal operations and to get rid of the smell. Contact a local HVAC company and ask about a safety inspection for your heating system.
4. A Burning Plastic Odor
The source of the odor is probably burning plastic from the vents or ducts. Another possible cause could be some plastic debris or a lost plastic toy wedged in an unexpected location. This odor often accompanies overheating problems as plastic wire coatings, capacitors, fan belts, and other components melt. Burning plastic is toxic; shut-off the furnace, contact an HVAC specialist, and explain the problem. In many cases, this is a quick fix or there may be an underlying issue to correct.
5. A Smoky or Oily Smell
This type of furnace odor is related to an oil furnace and the usual cause is a dirty oil filter. A simple oil filter change or cleaning the unit will usually fix the problem. If the odor persists, the cause may be a blockage in your chimney that needs to be removed. The best approach is to turn off the oil furnace and investigate further.
6. A Mildew or Musty Odor
If you turn on your furnace and you can smell a moist dirt or damp odor, there are a couple of potential causes to investigate. First, the air filter may be dirty and there could be mold growing in the unit. Replacing the air filter and cleaning housing with a white vinegar solution in a 1/1 ratio should kill any mold growing there. The other location cause could be the humidifier filter and the solution is the same.
7. A “Rotten Egg” Smell
This sulfurous odor cannot be ignored. If you smell this odor, it’s important to take it very seriously. Why? Natural gas has no odor, gas producers recognized that this was a problem because people had no warning that a gas leak was active in their homes. For this reason, gas companies add sulfur to the gas to make it easier to detect. Natural gas can cause house fires and/or explosions and if you smell the odor, it’s time to evacuate the home. Then contact the gas company and/or fire department to locate the gas leak and make it safe.
If you have concerns about your gas furnace or you’re considering an upgrade, contact your local heating and cooling specialist today.