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Heater Replacement Basics: Understanding AFUE!

After years of serving your Pasadena 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 Pasadena, 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 Pasadenaians, 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 Pasadena 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?

Pasadena’s Reliable Air Conditioning and Heating Company

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Peace Of Mind Guarantee
All technicians in your home have an extensive background check performed and are randomly drug tested for your safety.
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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.
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100% Money Back Guarantee
We guarantee that the system(s) we have installed in your home will heat or cool your home as we have stated.

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As always, service is the best! From responding to a call on a Sunday afternoon to returning the following day as early as possible to repair the issue. Professional service done on a timely manner. Deeply appreciate having AC working! Thank you!

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Daniel from Miles was fantastic. I’m so happy with my Miles AC unit and the continued service. I have peace of mind knowing my quality system is backed by a quality company. If you need HVAC work use these guys! You will not regret it.

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