We’re still in peak heating season, meaning you are probably using your furnace every week. While most furnaces are built tough and can sustain several months of frequent use, it is not normal for your furnace to start emitting nasty odors—in fact, some of these smells may be dangerous. Keep reading if you have ever asked yourself, “what’s that smell coming from my furnace?”, and remember that All Pro Plumbing, Heating, Air & Electrical is available 24/7 for all the furnace services you need.

Top 5 Furnace Smells

  1. Sulfur: That sulfuric, rotten-egg like smell may be familiar to homeowners that use a gas furnace. Natural gas is highly flammable, which means it’s one of the best combustible fuel sources for your heating needs. The flipside of this is that natural gas can be extremely toxic when inhaled, leading to coughing, dizziness, nausea, and fatigue. That’s why if you use a propane or natural gas-powered furnace, it is important to act immediately if you detect this rotten egg smell in your home. Remember, don’t try to find the source of the leak yourself. As our gas line experts know firsthand, this is better left to a professional, while you safely get your family out of the house.
  2. Dirty Socks: This one is a little less conventional than the smell of sulfur. We’ve all smelled that dirty sock, locker room, moldy cheese smell, but not all of us have dealt with it coming from our furnace. This sometimes happens, however, when bacteria start to build up inside your system, typically during the spring and fall when furnace coils cool with the outside temperature and then heat up when the thermostat is raised. This frequent oscillation between hot and cold can lead to increased moisture build-up, resulting in that bacterial odor you are smelling. The good news is that it is fairly easy to reduce condensation in your system by simply calling a technician for standard furnace maintenance. Our technicians at All Pro will happily replace your filter and scrub the evaporator coils with a safe cleaner. If the smell lingers after that, we suggest contacting our HVAC pros again for a thorough duct cleaning.
  3. Ozone: Have you ever stood outside in a storm (hopefully not for too long) and smelled a sharp, chlorine-like odor in the air? That scent you are detecting is actually ozone, which is commonly accompanied by thunder. We’ve all heard of the ozone layer, of course, but why would you be smelling ozone in your furnace? This can happen after your system’s blower motor goes through years of wear and tear, eventually causing it to bind up. When this occurs, your furnace will draw additional electricity, and this extra voltage may cause your motor to heat up. In some cases, your motor may get so hot, wires and insulation start to melt away. If this happens, you will likely notice your unit emitting sparks from electrical shorts. So really, what that ozone smell indicates is electrical burning—which is a severe problem, and should always be dealt with ASAP in order to prevent fire hazards.
  4. Diesel: The smell of diesel coming from your furnace is the smell of burning oil—plain and simple. “But wait?”, you may be saying, “if I have an oil-based furnace, isn’t it supposed to burn diesel?” This is technically true, but your system is designed not to release oil-related fumes into your air. If you are noticing this odor in your home, there may be clutter near your system that is catching fire from the pilot light. It’s also possible that the pilot light itself is not being ignited right as the oil is passing through the burner, creating a fog that, when ignited, leads to that diesel engine smell. Bottom line: if you have just filled your furnace tank with oil, a diesel smell is normal. However, if this smell lingers, or if you detect any signs of burning along with it, call a technician immediately.
  5. Dust: Have you noticed that your home just feels musty lately every time you run your furnace? This is fairly common. It usually means that your system has simply not been run in awhile, and the dust, dirt, and debris that have collected on the unit during months of disuse are burning away. Again, this issue is fairly common, though you can help get rid of it and improve your indoor air quality as well by calling for regular furnace maintenance. If that dusty odor persists more than a few weeks, however, you will probably need to replace your system’s air filter.

For furnace inspections, repairs, and replacements, call All Pro Plumbing, Heating, Air & Electrical today at (909) 500-8193, or click here to contact us online.