How big of an A/C unit do I need?
Why is it important to have an a/c unit that is the proper size for your home? Obviously if your unit is too small, it won’t keep your home cool. It will waste energy because it will be constantly running – trying and failing to cool things down. However, you also need to make sure that your unit isn’t too big either. Units that are too large will waste energy and cause your energy bill to be higher than it should be. To operate efficiently, modern a/c units need to run a full cycle. This means they steadily lower and maintain a temperature. If a unit is too big, it will quickly cool the space and shut off, without having run a full cycle. Then as the temperature starts to rise again, the unit will turn on, cool things down, and shut off – over and over again. All this turning on and off causes the unit to use a lot of extra energy. So if you’re asking yourself “How big of an a/c unit do I need?”, bigger isn’t always better. If you want to replace your A/C unit or need help with instillation contact Weather Crafters!
Central air conditioners are measured by the term “tonnage” – which has nothing to do with weight. A “ton” is the unit of measure used to describe an air conditioner’s ability to cool. A/C units range in size from 1.5 ton units to 5 ton units (anything over 5 tons is considered commercial, not residential). Units increase by the half-size so 1.5 tons, 2 tons, 2.5 tons, etc. Most homes will not need more than a 5 ton unit. If you do live in a large home that needs more than a 5 ton unit, then you will need to purchase 2 smaller units. For example, if your home rates for a 6 ton unit, you would purchase two 3 ton units instead.
Now that you know why you should have a properly-sized unit, and the sizes units come in, let’s look at how to actually calculate the answer to the question “How big of an a/c unit do I need?”. There are different ways to do the calculations – 2 of which will give you a ballpark answer.
- An equation → ((House square footage times 30, divided by 12,000) – 1.0) = Required Tonnage
For example, if you have a 1,700 square foot home, here is the math you would need to do:
- 1,700 x 30 = 51,000
- 51,000 / 12,000 = 4.25
- 4.25 – 1.0 = 3.25
We would need to round 3.25 up to the next half size. So for a 1,700 square foot home, you would need a 3.5 ton a/c unit to efficiently cool your home. This equation is based on an average American home, but for homes in especially hot and dry areas, like the southwest, skip step 3.
Another way to get a ballpark answer for “How big of an a/c unit do I need?” is based on the different climates throughout the United States. Check out this link to see the different regions and what size unit you need, based on your home’s square footage. https://www.resourcesforlife.com/wp/wp-content/uploads/2017/05/20170511th0904-central-air-conditioner-tons-size-capacity-output-cooling-house-home-space-calculator-chart-table-guide.jpg
For a more accurate calculation, get in touch with Weather Crafters. We can help determine exactly what size a/c unit would be best for your home, and recommend the best brand and model. We are here to answer any questions you may have. If you are wondering “How big of an a/c unit do I need?”, “Is it time to replace my current a/c unit?” or “How do I install an a/c unit?”, give Weather Crafters a call. Don’t break a sweat this summer, let Weather Crafters keep you cool!
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