AFUE Ratings: Understanding Furnace and Boiler Efficiency
Do you know what AFUE ratings are? Chances are, if you live in New York or Long Island, a furnace or a boiler heats your home. Many people confuse the two, using boiler and furnace interchangeably, not realizing that there are profound differences between the two systems. And AFUE ratings are a way of measuring a furnace of boiler’s efficiency.
Furnaces heat air and distribute it through the house via ductwork, and boilers heat water and provide either hot water or stream for heating. Steam is delivered by pipe to steam radiators and hot water is used for baseboard radiators, radiant heating systems and coil heaters.
In either case understanding how to assess the efficiency of these two systems is the key to making sure you are purchasing the right boiler or furnace for your home.
Know Your AFUE Ratings
A central furnace or boiler’s overall efficiency is measured by something called AFUE (Annual Fuel Utilization Efficiency), and all new furnaces and boilers are required to display their AFUE ratings so that homeowners can compare the efficiency of each product.
To be more specific, AFUE is the ratio of annual heat output of the furnace or boiler compared to the total annual fuel energy consumed. For example, an AFUE rating of 80% means that 80% of the energy in the fuel becomes heat for your home and the other 20% dissipates, evaporates or escapes up the chimney. It is important to note that AFUE ratings do not include heat loss through ductwork or piping, and some of this heat loss can be as much as 30% in poorly insulated situations.
An all electric boiler or furnace usually has an AFUE rating between 95% – 100%, with lower values for units installed outside because they have a high degree of heat loss. Unfortunately, due to the high price of electricity in the tri-state region most of the efficiency savings are negated by high electrical costs.
If you are considering the purchase of a new boiler or furnace, please keep these ratings in mind. If you are looking to upgrade the efficiency of your boiler or furnace, contact a trusted HVAC contractor and discuss having them perform a retrofit on your current system.
