Sometimes, the questions you come up with as a homeowner are not ones you ever expected you'd have to ask. For instance, after you turn the heat on for the first time in a while, you might find yourself asking if your furnace should smell. Unfortunately, this is not a yes or no question. In some cases, an odor from your furnace may be pretty normal, even if it is not ideal. In other cases, it really does mean you need to call a furnace repair company. A good approach is to consider what your furnace smells like and then review the following guide.
Does your furnace smell like an old, dusty jacket you pulled out of the back of a closet? Maybe it smells like your rag after you dust some dirty furniture. The good news is that this odor is pretty normal, especially if you just turned your furnace on for the first time in a while. What you're smelling is the dirt in your ducts getting blown out into your space. Changing your air filter more often may help with this, but there's no need to call in the pros.
Does the smell remind you more of a musty basement or an old, moldy shower? If this is the case, then you probably have mold growing in your ducts. An HVAC contractor can clean out your ducts. Long term, installing a dehumidifier may help prevent this issue from coming back as it will ensure your ducts don't hold enough moisture to grow mold.
If your furnace smells like metal, or more specifically like burning metal, then you need to turn it off right away. You might have an electrical component that is failing or that has already failed. This can sometimes lead to a fire. An HVAC contractor can come identify and hopefully replace the damaged part. Often, it is the contactor, the capacitor, or some wiring that leads into the furnace.
Does the odor remind you of something rotten, or more specifically, rotten eggs? This often points to a gas leak. Turn the furnace off, and make two phone calls: one to your gas company and the other to your furnace repair contractor. The gas company will need to fix the issue if it is inside a gas line, and an HVAC contractor will need to fix it if it's inside the furnace itself.
Some furnace odors are not a big deal, but others do mean you need repairs. Contact a heating contractor to learn more.