Not all smells are bad. Even when it comes to your furnace, some smells should not alarm you. A musty odor when you turn the furnace on for the first time just means you have a little dust in the system. Even a slight burning odor at this point usually just indicates dust on the burner. However, this does not mean all the smells coming from your furnace are harmless. There are a few smells that indicate a problem and should inspire you to call a heating repair contractor.
The smell of metal is hard to describe, but when you smell it, you will know. It may remind you of the taste of iron in your blood. Metallic odors can sometimes mean there are two metal components rubbing together inside your furnace. The odor is coming from the small amounts of metal that are heated up and rubbed in the process.
Metallic odors can also indicate an electrical problem in some cases. You may be smelling an electrical wire burning.
In either case, you should have an HVAC contractor come take a look and make the required repairs. Electrical issues could lead to a fire if not addressed, and friction between two metal parts could also lead to sparks that cause fires.
Rotten Egg Odors
The smell of rotten eggs is unmistakable. That sulfurous odor almost always means you have a gas leak somewhere. If the leak is in the furnace itself, your furnace may turn on and off too often as it triggers a limit switch. However, if the gas leak is located in one of the lines leading to your furnace, then your furnace may go on working like usual in spite of the leak.
Gas leaks can lead to illness and also to fires. So, if you think you have one, turn your heat off and call your HVAC contractor. If you can smell gas even outside of your basement, leave the home until your contractor arrives. They can look over your system, and if needed, have a natural gas company come take a look, too. Most gas leaks are not difficult to fix.
Throughout the heating season, pay attention to how your furnace and heated air smell. If there are odors like the ones above, you should call an HVAC contractor. Often, the odor of rotten eggs or burning metal is a warning sign that something is amiss and needs attention before you have a fire or other calamity.