What size HVAC system should I have? | Classic Air

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Beating the summer heat or staying cozy has never been easier with easy access to heating, ventilation, and air conditioning (HVAC) units to suit nearly any home. Like homes, they come in a variety of sizes that must be matched to the cooling needs of your home. The problem arises when your HVAC unit is too big or too small for the job. Both can cause a spike in your energy costs and affect the comfort level of your home. Sizing the unit to your home is an important part of living comfortably while keeping cooling costs under control.

Isn’t bigger better?

It’s logical to assume that a bigger unit will do a better job of cooling or heating your home, but this isn’t true. If the unit is too big, it will become an energy hog and your electric bill will skyrocket. The reason for this is simple. Large units kick on and cool or heat your home quickly without going through the entire cycle before shutting off. When the temperature in your home changes, the unit kicks on again and sends a burst of cool or warm air throughout the house for another rapid cool down or heat up. That causes the HVAC unit to consume massive amounts of electricity compared to the smooth operation of an appropriately-sized unit. It might also create uneven temperature levels in the home.

Doesn’t a smaller unit use less electricity?

Again, that is a reasonable assumption, but in practical use it doesn’t hold true. A unit that is too small for your area will run constantly as it tries to keep up with the demand for heating or cooling. This puts stress on the unit and puts a dent in your wallet as well. It might keep your home comfortable, but because a unit that is too small needs to work harder to keep your home at a comfortable level, it will raise your electrical bill.

Follow This Formula to Determine Your HVAC System's Efficiency

How do you determine the correct size of HVAC unit?

Many homeowners are surprised to learn there is a formula for determining the correct size HVAC system for their home based on the square footage of the house. To use the formula, multiply the square footage of your home by 25. Next, divide this number by 12,000 and subtract 0.5. This number represents the number of tons required to cool your home efficiently.

For example, if your home is 1,000 square feet, you need to multiply 1,000 by 25 to get 25,000. Divide the 25,000 by 12 to get 2.08. Subtract 0.5 from 2.08 to arrive at 1.58. You will need a 1.5 to 2-ton unit to cool your home.

Other Circumstances to Consider

The above formula will give you a rule of thumb for determining your heating and cooling needs, but there are other factors to consider. The region of the country you live in also affects the size HVAC unit you will need. Those who live in the blistering heat of the south might require a slightly larger air conditioning unit that those in the north who experience cooler summer temperatures, and those in the north may need a better furnace.

If you have questions about how other factors may affect the size of AC unit you need, call your local HVAC contractor. The servicemen are trained in both heating and cooling systems and can help you decide what size is most appropriate for you.

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