When it comes to air conditioning, size matters. If you have a large home, you need an appropriately sized air conditioner to ensure that your home is comfortable and energy efficient. But how do you know if a 3-ton AC unit is big enough for a 2400 sq ft house?The general rule of thumb is that you need 400 to 600 square feet of cooling capacity per ton of air conditioning. So, for a 2400 sq ft house, you would need a 4-ton AC unit.
However, this rule of thumb doesn't always apply. If your home has a lot of windows, is an older house, or is located in a hot city like Las Vegas, you may need more cooling capacity per ton. In this case, you may need 300 or even 400 square feet per ton. To determine the exact size of the air conditioner you need for your home, divide the load or capacity by the floor area. For example, a 3000 sq ft house with a 3-ton air conditioner would have 3 ÷ 3000 = 0.001 tons per square foot.
This number is too small to be useful, so we can use 1000 square feet per ton as an estimate. Of the 167 zones studied in one research project, only 53 were less than 1000 square feet per ton and only 20 areas were less than 700 square feet per ton. This means that only 12% of the areas in this group could have been close to having refrigeration equipment of the appropriate size according to the 400 to 600 square feet per ton rule. The average load of the 75 homes studied was about 1200 square feet per ton. In these 63 homes, 151 individual heating and cooling systems were selected. The average capacity of these systems was 856 square feet per ton - 28% higher than the average refrigeration load. When selecting an air conditioner for your home, it's important to consider the number of square feet per ton you need to cover.
If it's less than 1000 square feet per ton for newer homes, then either the number is wrong or your house isn't as efficient as it should be. For example, in my approximately 2400 sq ft vintage house from the 1920s, I have a 1-ton Midea modular vibrator (basically a minisplit in a can) mounted on the window of my office loft high up the stairs. With all interior doors open, it covers 100% of my 1% cooling load (1% local temperature container = 83°F) at an average indoor temperature of the mid-70s F. That's a ratio of tons to 2400 feet under design conditions. Without the window unit turned on and running my ridiculously oversized central air with 5-ton ducts, the duty cycle never exceeds ~ 50%, even when outdoor temperatures are around 90°F (like now). This implies a load ratio of one ton per 1000 feet at outdoor temperatures 10°F or more ABOVE the design temperature of 1%.To sum up: if you have a 1200 sq ft home, you'll need a two-ton unit; if you have a 2400 sq ft house, you'll need a four-ton unit; and if you have a 3000 sq ft home, you'll need a six-ton unit.
There are also 2.5 ton and 3.5 ton units available in case your square footage isn't perfect for a two- or three-ton unit. Remember that other variables such as insulation and type and number of windows in your space can also affect your AC needs. The best way to determine what size air conditioner you need is to consult with an HVAC professional.
