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Heater Replacement Basics: Understanding AFUE!

After years of serving your Katy home, your heater is ready to be upgraded. The good news is that you’re about to get dependable and consistent heating in your home. The stressful part can be deciding what heater is best for your home.

Here at Air Tech of Katy, we believe in a comprehensive HVAC approach for our heater replacement services. That means we want to provide as much information as we can to help the heater replacement process go smoothly. One of the most important factors of your heater is its efficiency. Keep reading to learn all about AFUE and your new heater’s efficiency.

What Is AFUE?

When it comes to an efficient furnace, the rating to pay attention to is the AFUE. The Annual Fuel Utilization Efficiency (AFUE) determines how much energy the heater has to use in order to heat the home to the desired temperature. Every heater uses some kind of fuel source (gas, propane, electricity), but the less fuel it has to use, the better. Less energy consumption means major savings, both for the environment and your wallet!

What’s The Most Efficient Furnace?

The best furnace for your home and the most efficient furnace aren’t necessarily the same thing. For furnaces specifically, the EPA enforces a minimum of 78% AFUE for all manufactured heaters. Any heater that operates between 80 – 89% efficiency is considered a mid-level efficiency furnace. Anything over 90% is considered high-efficiency. For electric furnaces, some claim the absence of wasted energy makes the unit 100% efficient.

What Affects Heater Efficiency Needs?

When choosing the furnace that works for your home, the most efficient unit depends on more than just efficiency. One of the most important aspects to keep in mind is the climate you live in. For us Katyians, our heating concerns include humidity levels as well. Texas is one of the warmest climates, even in the winter. This means that your heater usage might not be as heavy as other parts of the country, even though you still need powerful dehumidification.

How To Calculate How Much Heating Power You Need

One of the main things to remember is that when fuel is combusted, some energy is lost as waste. A furnace may use 50,000 British Thermal Units (BTUs) of energy, but it won’t produce that much heat. This is what makes input energy and output energy different. To know how much heating power you need in your home, you need two numbers: the output energy of the heater and the heating load of your home.

Use this equation to calculate the heating load:

(home square footage) x (35BTUs) = total BTUs


(2,500 square feet) x (35 BTUs) = 87,500 BTUs

If you want to determine how efficient your new heater needs to be, there is a simple formula that you can use if you have a couple of key pieces of information. First, you need the input energy that is measured in BTUs. This number can be found with the heater’s detailed information. Next, you need the AFUE or efficiency ratio. If the AFUE is 80%, you would use .8 in the formula.

(Energy input) x (AFUE) = energy output


(87,500 BTUs) x (.8) = 70,000 energy output

In the example above, the 2,500-square-foot house would need a larger, more efficient furnace to produce 87,500 BTUs to the home.

Need Expert Help?

If you don’t feel comfortable calculating your heating load or heater efficiency, the pros at Air Tech of Katy would be happy to help. Let us get you a precise and accurate heater to warm your home for the coming years. Contact us today to start your service request!

Why Choose Us?

Katy’s Reliable Air Conditioning and Heating Company

Peace Of Mind Guarantee
All technicians in your home have an extensive background check performed and are randomly drug tested for your safety.
30% Utility Savings Guarantee
You will save a minimum of 30% on your heating and cooling costs or we will refund double-the-difference of your savings not realized during the first year.
100% Money Back Guarantee
If we do not have your new system operating by the date promised, we will pay you $500 for your inconvenience.

What Our Customers Have To Say

Professional & Informative

Michael was very professional and very informative. He went the extra mile to test our furnace for Carbon monoxide. I was very pleased and impressed with his knowledge.

Ken G.

Helpful & Friendly

Had to have an AC unit replaced. Chad was very helpful, friendly, honest, and on time. Very professional!

Alyssa D.

Experienced & Professional

Rick is the best. He knows his stuff. He was able to fix our problem when 4 other companies couldn’t. We aren’t going anywhere else and he is definitely worth waiting for.

Mathew Z.

Knowledgeable & Friendly

Great attentive and knowledgeable technician. The best in five years. Patient and expressed non-technical and technical language on service protocols; Will request same tech on next service.

Mark T.