If your heating bill is constantly on the rise, then your furnace and HVAC system may be losing their efficiency, which can be an indication of a number of problems. You may have issues with your vents and air ducts, you may have a bad furnace burner, and you may have a clogged air filter. If some of your vents are closed, you can create a cool zone in your home, which — if the thermostat is in this zone — could trigger your furnace to work overtime. In addition, you may have a blockage in your air ducts (e.g. an animal nest, dust, etc.), which is hindering the performance of your furnace. If you have bad burners in your furnace, then your furnace won’t heat up as efficiently as it was designed. Your furnace’s burners can become dirty and clogged over time, which will restrict the flow of gas to create a flame in your furnace. You may also have a clogged air filter. Your air filter will, over time, capture dust and debris from the air that is forced through the filter (which is the purpose of the filter). Eventually, however, this debris can build up and choke the air supply to your furnace, which means that your HVAC system won’t have the flow that it depends on.