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Calculating Your Heater Size (Heater Installation Made Easy)

One of the most important decisions you need to make when investing in a new heater is what size to purchase. Before you worry about which brand is better or how you can make the purchase more affordable, you should get an accurate calculation on a heater size that will be able to produce the warmth you need in your home.

Express Air Conditioning and Heating has installed more furnaces and heating systems than we can count, so we know a few things about Pensacola heater installations. Keep reading to learn the importance of an appropriately sized heater and the heat load calculations we use to determine your perfect heater size.

Is Heater Size Important?

In short, yes! Not all homes are the same, so your heater can’t be just like everyone else’s either. Your heating system is designed to match the volume and demand of your home, so the more accurate the match is, the more comfortable and efficient your home will be.

For example, you may think that the biggest unit you can afford will be the best for your home. This will ensure your home is warm, but your system regulates more than just temperatures. A heater that is too large won’t be able to dehumidify effectively, leaving your home muggy and miserable during the more humid months in Pensacola.

Similarly, for a unit that is too small, your home won’t be regulated correctly. The system will run long cycles, trying to keep up with the heating demand. This process will use more energy than usual, and your home may take a long time to warm up.

How Do I Pick The Right Heater Size?

First and foremost, a professional HVAC or furnace specialist is your best option. Letting an expert evaluate your home and heating needs will produce a much more precise recommendation. Our technicians take everything about your home into consideration, including sun exposure, insulation and more. However, if you’d like to estimate the heater size you might need yourself, there are some simple equations you can start with.

Calculating Heater Sizes

Most heaters that are part of an HVAC system will be measured in tons. No, that’s not the actual weight of the system! A ton is simply a unit of measurement. Another important unit of measurement when it comes to heating is British Thermal Units (BTUs). You’ll need both of these to get your final heater size.

First, you’ll start by getting the total square footage of your home. This number should be on official documents, or you can estimate by measuring the length and width of each room. Next, plug in that number to the following equation to get your necessary BTU output.

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

Example:
(2,500 sq. ft.) x (35 BTUs) = 87,500 BTUs

Then, you need to transition from BTUs to tons. Each ton is worth 12,000 BTUs of heating power. Simply divide your total BTUs by 12,000.

Example:
87,500 BTUs/12,000 BTUs = 7 tons

A professional can use this information to install two 3 ton units at opposite ends of your home.

Calculating Furnace Size

The process for calculating a furnace size is similar, but furnaces aren’t measured in tons. It’s more important to match the total BTUs needed to the efficiency of the new furnace. Furnaces that use combustible fuel (like natural gas) aren’t 100% efficient. This means that some energy is always lost during the heating process. You need to make sure that the BTU output after the combustion process has occurred still provides enough heat for your home.

In the example above, the 2,500 square foot home needs 87,500 output BTUs to warm the home. Use this equation to calculate output efficiency of the new furnace.

(input BTUs) x (% efficiency) = output BTUs

Example:
90,000 x .85 = 76,500 BTUs
105,000 x .85 = 89,250 BTUs

If you’re looking at a furnace that has 90,000 input BTUs and an 85% efficiency rate, the output would only be 76,500 BTUs. However, 105,000 input BTUs would produce 89,250 output BTUs.

Get Professional Assistance

If these equations help you start to determine what size heater you need to invest in, then we’re happy to help! Express Air Conditioning and Heating is also available to double-check your calculations and give you any help you need to invest in an efficient heater. Give us a call today for all your heater replacement needs!

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