The cold winter months are slowly starting to draw in on us, and you need to keep your house heated. You've turned on the furnace to get nice and toasty, but something seems to be wrong. What's happening? Well, it can be for a number of reasons, but sometimes furnaces break and you need to get a new one. It's important for you to spot the signs of a broken furnace early so that you can get it replaced as soon as possible. Here's a quick guide.