Is optimum furnace efficiency possible in your home? Your furnace comes from the manufacturer with an official efficiency rating called AFUE (Annual Fuel Utilization Efficiency). This figure expresses the percentage of energy consumed that actually contributes to usable heat versus the amount lost in the combustion process.
Today, standard efficiency furnaces have AFUE ratings around 80%. More expensive high-efficiency furnaces with secondary heat exchangers deliver efficiency as high as 95% AFUE.
Here are some reasons why your furnace may not be living up to current furnace efficiency standards:
It’s too old.
Gas-fired furnaces last 15 to 20 years so a unit still on the job today may have been manufactured to meet AFUE standards that were lower than present minimums. If you don’t know the age of your furnace, write down the make, model and serial number. Contact the manufacturer to get an age estimate. If it’s more than 15 years old, upgrading to a new furnace built to today’s higher standards may be the best way to improve efficiency.
Every furnace should receive annual maintenance by a qualified HVAC service technician. This includes a list of manufacturer-approved procedures that support optimum efficiency as well as maximum performance , safe operation and lower heating costs. Most manufacturer’s warranties also require this to maintain coverage. If professional preventive maintenance has been neglected, schedule a furnace tune-up now to improve efficiency.
Every new furnace installation should include a professional heating load calculation. This determines the ideal BTU capacity to meet the unique heating requirements of the home. Over-sized furnaces cycle on and off too rapidly and degrade efficiency while under-sized units don’t heat the house uniformly and run overly-long cycles.
Heating-related issues outside the furnace itself can have a major effect on furnace efficiency. For example, deteriorating ductwork that leaks conditioned air can cause the furnace to run extended cycles to maintain thermostat settings, reducing efficiency and raising operating costs. Insufficient insulation, especially in the attic, can also impact furnace energy consumption.