If your furnace dates from 1992 or earlier, it's obsolete. Even if you have a heating system that is running well but is only 10 to 15 years old, you have an outdated furnace that produces significantly higher energy costs than today's high efficiency models.
Obviously, if you encounter problems with your old furnace, it's time for a new one. Consider purchasing a new unit, however, not only to save on energy costs, but to also experience more comfort inside your home during long Canadian winters and to be kinder to the environment in a world with diminishing natural resources.
Today's furnace manufacturers strive to produce heating units that burn fuel efficient and require minimal energy to run blowers circulating heat through your building. All new furnaces have an Annual Fuel Utilization Efficiency (AFUE) rating that indicates its efficiency measurement for delivery heat. AFUE ratings range from 80 percent to over 98 percent, indicating the ratio of the furnace's fossil fuel use that is converted into usable heat. The higher the number, the more efficient the heating unit is. AFUE ratings do not take into account the loss of heat that naturally occurs in a building's ductwork, which can be as high as 35 percent.
Technically, high efficiency furnaces are those models with an AFUE rating of 90 percent or higher. Those lower are referred to as mid efficiency systems. Future AFUE requirements will also take into consideration type of fuel used and whether the unit is built for outdoor installation or only for indoor use.
In addition to AFUE ratings, high efficiency furnaces also have a number of other features that save on fuel and energy costs. One area that has seen many technological advances resulting in improved efficiency during the past decade is the combustion side of the furnace where outdoor air is carefully mixed with fuel and delivered at a controlled rate to maximize heat throughout the building. Two-stage furnaces, where gas valves measure outdoor air temperature and deliver less heat in milder weather, make gas flow more economical. Unlike conventional systems where the furnace blows hot air into your home at high speed, two-stage units run blowers for longer periods at lower speeds, thus providing quieter and more comfortable, even heating. As temperatures become more extreme outside, more fuel is delivered to the burners, keeping your home cozy during the coldest weather in harsh northern climates.