AFUE rating

What is an AFUE rating?

The more efficient your furnace is, the more you’ll save keeping your home warm. An easy way to know the efficiency of your furnace is to check the AFUE rating. AFUE stands for Annual Fuel Utilization Efficiency. It’s a government rating that is an estimate for real-world conditions. 

All AFUE really means is that if your furnace has a high rating, it is very efficient when it comes to converting fuel into energy. If it has a low AFUE rating, the opposite is true. For example, a furnace with an AFUE rating of 83 can turn 83 percent of the energy it consumes into heat. 

Ideally, you would like to get a unit with the highest AFUE rating possible. This is because if you buy a furnace with a 95 percent AFUE rating, every dollar you spend on fuel, 95 cents of it will go to heating your home and 5 cents will be wasted. If you buy a furnace with an 80 percent AFUE rating, 80 cents of every dollar will go to heating your home and 20 cents will be wasted.

These days, a mid-efficiency furnace will have an AFUE rating between 80 and 85. A highly efficient furnace will have an efficiency rating of 90 percent or higher. The minimum AFUE rating for gas furnaces is 78.

The upside of having a highly efficient furnace is, of course, that they will save you money in the long run. But, generally speaking, they’re going to cost more upfront. If you turn your furnace on in the fall and crank it up all winter, it may pay for itself fairly fast. If you usually bundle up in blankets and keep a fire going in the fireplace rather than relying on the furnace, it could take longer.

The quickest way to check the AFUE rating of your furnace is to see if there is a yellow sticker on the outside of the furnace that lists the rating. It will also list your SEER rating, which is important in warmer months. But if your furnace doesn’t have one of those stickers, and it’s an older model, it is very likely not a high-efficiency furnace. Typically, models become less efficient over time so, for example, if you have a 12-year-old model with an AFUE rating of 80, it may no longer be functioning at the level.  

High-efficiency furnaces also have a newer style of blower motor that works more efficiently. The blower motor is doing all the work to blow heated air through your vents when the heating system is on and cold air when the AC is on. A high-efficient HVAC system with a highly efficient blower motor will save you money year-round.

If your system is no longer efficient enough for you, TMC would be happy to help you replace it with one that is.