Using your furnace can be necessary for your family’s comfort if you live in a colder climate. Unfortunately, from time to time it is possible for your furnace to produce strange smells, especially if your furnace is over 20 years old. There are several reasons why most furnaces can smell funny, and while some reasons may be a cause for immediate concern, other smells can go away on their own. Here are some smells you may experience from your own furnace, and what you can do about them. If you smell rotten eggs or sulfur coming from your furnace, you could have a gas leak. Natural gas is odorless, however companies use additives to alert users of its presence. If you smell rotten eggs or sulfur coming from your furnace, it is best to turn your furnace off, and contact your gas company right away. If you smell burning metal or oil coming from your furnace, you may have a mechanical issue. Over time, certain parts of your furnace are designed to wear down, especially if your furnace is over 20 years old. If you smell burning metal or oil coming from your furnace, turn it off, and contact your local HVAC company. If you smell burning dust coming from your furnace, this is usually not a huge deal. Over the summer, when you aren’t using your furnace, it is possible for dust to accumulate within your ductwork, and become ignited when you turn on your furnace for the first time, but this smell will usually go away on its own within a couple of hours. For any other smells coming from your furnace, it is usually best to turn off your HVAC system, and call a professional.