What is AFUE? Is a 95% furnace really worth it?

How Do I Figure Out My Potential Savings?

What are the Benefits to a Higher Efficiency Furnace?

AFUE

AFUE stands for Annual Fuel Utilization Efficiency and is the standard the industry for measuring the output Btus of furnace given its input Btu’s. It tells us how much energy the furnace wastes without any regard to the air duct distribution system.

A 100,000 Btu furnace with an AFUE of 72 means that you will burn 100,000 Btus of gas and only achieve 72,000 Btus of output. You would be wasting 28,000 Btus of heat. That is a 28% waste of money when you pay your gas/propane bill and this is just the star of the waste. Couple this with some problems in the air ducting and the waste can be magnified by twice or more.

A modern high efficiency furnace of 95 AFUE has that same 100,000 Btu furnace putting out 95,000 Btus and only wasting 5%. That is money in the bank and it is both short term and long term money in bank.

How To Figure Your Savings

Take the monthly amount of money that you pay for gas/propane in the winter during a month when you use the home heater. January, February or December. Now subtract from that the amount of money you pay for gas in a month that you don’t use the heater, like June, July or August. The difference is the approximate amount of money that you are paying for your heater. It will be off a little bit due to water heater use, but not much.

Now take the efficiency of your existing furnace, most standing pilot models are 60-72% AFUE when they were new, and divide it by the AFUE of the furnace that you are thinking of getting. Take that fraction and multiple it by the monthly gas bill you figured out in the previous paragraph. that will be the approximate amount of your new gas bill using the exact same air duct distribution system you have. Fix the air ducts and you may be able to cut that amount in ½ or more. It is seriously a lot of money over the years. Most people will save enough to pay for their furnace.

Example……..60AFUE/95 AFUE x $ 130 a month = a monthly savings of $82 on the gas bill alone.

The Benefits of a High Efficiency Furnace

Aside from the money is the level of comfort. A 95% + AFUE furnace will typically have a multi-stage gas valve and a variable speed motor. If you have allergies this is the way to go. A variable speed motor will consume on average, during circulating mode, about 40 to 50 watts of electricity. This correlates into about $5 a month in electricity for circulating the air. This is the air cleaning mode. A standard efficiency furnace with a standard PSC (Permanent Split Capacitor) will consume about $65 a month in electricity when run 24/7.

More Comfort is achieved with a multi-stage furnace. Think about how uncomfortable your car would be if you only had a single gear and that gear was wide open throttle all the time. You would be in a perpetual drag race. Very uncomfortable. Now add gearing to that car, up to 64 different gears. That is what a high end high efficiency furnace does. It slowly ramps up the hat as needed and blasts if required. It helps to provide a more even quieter warm indoor air environment.