When colder weather approaches in Ontario, the last thing you want is to discover that your furnace cannot keep your home warm. Heating problems often appear gradually, but the early warning signs can be easy to overlook while the system is still running.A strange noise might seem harmless. A chilly bedroom may be blamed on a draft. A furnace that turns on more often than usual might not attract much attention until the next energy bill arrives. However, these changes can indicate that the sy...