There are a number of signs your furnace is in need of repair, and most of them are quite obvious. If your furnace stops working and the power supply has not been interrupted in some way, you probably need to call a qualified service technician to come and take a look at your furnace.

Other obvious signs are uneven or irregular burner flames, a cracked heat exchanger, strange sounds, or short cycling. If you own a gas furnace and you smell gas anywhere in your home, it could be a dangerous situation and you should shut down your system, cut off the gas supply to your furnace, and immediately call a qualified repair technician.