A new furnace or boiler is a great way to save money on your winter heating bills. Or so all the 'experts' say, but how do you know for sure? And how do you know how efficient, or not, a particular furnace or boiler will be? The key is in the AFUE.
AFUE = How Efficiently You Burn Money
Say what now?
From a certain point of view, you are burning money every time you turn on the heat. You're not getting that heat for free. With a furnace or a boiler, you're either paying for natural gas or propane service to keep the unit going. Without fuel, the best furnace in the world is about as useful as a solid-gold life jacket.
Which brings us back around to annual fuel utilization efficiency.
Annual fuel utilization efficiency, AFUE for short, is how we measure the approximate thermal efficiency of a furnace or boiler. I say approximate, because it is truly an estimate of how effectively the unit will operate over a typical heating season. Which is more useful than simply testing the furnace under ideal circumstances and calling it a day. After all, very few people need heat in ideal circumstances.
Optimum Operation
What kind of rating should you look for in a new furnace or boiler? As with most things, higher is better. 80% AFUE is solid performance, and is about the lowest rating you will find on new products. The very best units on the market exceed 90%.
Should you get the bare minimum or the higher performer?
Depending on where you live, how expensive fuel is locally, and how much energy you need for winter heating a 10%-15% difference in costs could be trivial or quite substantial. The only way to know for sure is to do the math yourself. How much do you spend on heating fuel? How much money would a higher rating save you? Will that pay itself back over the life of the unit?
Investing in the higher efficiency unit will definitely make sense for some folks. For others who live in milder climates and don't need as much heat, a more economy focused model will work just as well. In either case, understanding AFUE will help you make a better decision about your next space-heating system.
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