Whether you live in the southern U.S. or one of the cold northern states, keeping your home cozy in the winter and cool during the summer months is essential. With heating and cooling units, it’s necessary to understand how they are sized. You generally want to use as small a unit as possible while complying with all applicable codes. This is a simplified overview of things to consider when determining what size air conditioning unit you need.

Understanding AC Measurements

Understanding how to measure AC is essential to understanding why you do it and its meaning. The air temperature in your home can fluctuate by several degrees during the day, so measuring and monitoring the temperature is so important.

Imagine a world where homeowners and businesses could use cooling units seamlessly, safely, and efficiently as heating units. That’s the idea behind Seasonal Energy-Efficiency Rating (SEER), which facilitates high-performance cooling by improving heat transfer within a given air volume, maximizing energy efficiency, and minimizing noise levels. SEER is an EPA-developed rating system that calculates cooling efficiency based on unit size, CFM air volume (cubic feet per minute), and temperature rise. Measurements are taken over a period that simulates actual cooling conditions in a home or business to arrive at the SEER rating for each unit.

The higher the SEER rating, the more energy-efficient the unit is likely to be when it’s in operation. Two critical variables are included in this calculation: load and ambient temperature. The first is how much air conditioning power an air conditioner needs to cool down a house based on its size, layout, and insulation. The second variable, ambient temperature, measures how hot or cold it will get outside during each season of use.

Why Size Matters

An air conditioner’s ability to effectively cool a space depends on the size of the unit and where it’s being installed. If you have an area that needs cooling for six or more hours per day on average, you might need a more oversized air conditioner.

5 Things to Consider When Determining What Size AC Unit You Need

When determining what size AC unit you need, efficiency is important but not the only factor to consider. You must consider these five things to ensure that the unit you select will be the right fit for your home and family.

1. House Size

The first thing to consider when determining what size air conditioner you need is the size of your house. Contractors and technicians use a few different formulas to determine how large an air conditioner should be. Still, the easiest way to calculate it is using feet (for rooms) and BTUs (for cooling capacity). The average bedroom takes about 150 square feet, or roughly 12 feet by 14 feet. Add 25 square feet for each additional bedroom. Divide this by 100 if you want to get a rough estimate in BTUs. Therefore, a room that’s 15 feet by 20 feet would take about 1,300 BTUs (1,350 square feet / 100 = 135 x 20). The living room would need at least 2,000 BTUs whereas the dining room could use up to 3,000 BTUs, depending upon its size.

Another thing to consider when determining what size AC unit you need is the house style. Larger homes with more windows and external walls will require more airflow for cooling, especially with an open floor plan. The amount of air coming into the unit must match the amount of air going out; otherwise, temperature differences will cause airflow problems.

2. Location

The most important thing to consider when buying an air conditioner is the location of your home. The kind of cooling you need depends on where it will be housed because different areas have different temperatures, humidity levels, and wind patterns. It would be best to consider whether the place you live has winters with snow or warm summers with a lot of humidity.

When determining what size cooling system you need, location is critical. If you live in a hot climate where temperatures can reach over 100 degrees for nearly half of the year and humidity is high, it’s best to get a unit with a higher SEER rating. For example, if you live in an area with an average summer temperature of 85 degrees Fahrenheit with an intermediate humidity level of 50%, then a 3-ton AC unit would be appropriate.

3. Number (and Type) of Windows

Before deciding on what size AC unit you need, you may want to consider the number of windows in your home, the size of each window, and how much glass there is. Your HVAC technician can help you determine the extent of window units appropriate for your space.

4. Existing Insulation and Ductwork

The amount of existing insulation affects how much heat can get into and out of your house. If there is a lack of insulation, it will be much more difficult for an AC unit to keep your home cool during the hot summer months. Proper insulation will improve energy efficiency by reducing energy leakage within your home. Suppose you have older, less-efficient windows or poor attic insulation. In that case, you may need a more extensive cooling system to get the same amount of cooling effect as someone with newer windows and more efficient attic insulation.

If you have existing ductwork, look at the space between the floor and the bottom of the ductwork. If the ductwork is filled with insulation, you will need a room at least 6 inches larger than the recommended unit size to allow for installation. If only part of it is filled or if there are holes in it, go ahead and use a smaller unit than recommended by our HVAC professional.

5. Ceiling Height

Ceiling height is perhaps the most crucial consideration when determining what size AC unit you need in your home. If you have high ceilings in your living room, dining room, and bedrooms, you’ll want to select the largest air conditioner to fit comfortably into that space. In addition to your ceiling height, another factor to consider is whether or not there’s a fan already installed in the room you wish to cool down. If so, you may want to select a smaller AC unit than you would if there were no fans present in that particular area of your home.

Contact Us for Professional AC Installation

Determining the size of an AC unit that you will need to cool your home is essential to avoid being left with a unit that doesn’t sufficiently cool your home or one that is too big and wastes energy. The considerations outlined above will help guide you to the proper unit for your space. We provide HVAC services for our residential and commercial clients. Our team of professionals from Fusion Plumbing & Air can assist you in selecting a suitable air conditioning unit for your needs. We offer free HVAC unit sizing quotes to help you make the best choice in Tucson and throughout the Greater Phoenix area.

With the information we’ve provided, you should be able to confidently decide on the size of AC unit that’s right for your home. Whether you’re looking for mini-splits, central air conditioners, or other measures, you now have the information necessary to choose the best option. And before you go rushing out to get an AC unit for your home, check out our page about financing with Fusion Plumbing & Air first. With our no-obligation estimate form and free quotes, it’s easy.

Fusion Plumbing & Air

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