How to Size Central Air Conditioning Units
An air conditioner's size is measured by British thermal units. Each Btu is the amount of energy required to raise the temperature of a single pound of water a single degree. The amount of Btu that your central air conditioning unit will need depends on the side of your house, whether your home is insulated and for what purpose your rooms are used. Does this Spark an idea?
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Instructions
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1
Determine the square footage of the area the central AC unit will have to cool. You can do this by multiplying the length times the width of each room that will be cooled and then adding the totals together.
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2
Estimate the number of Btu your central air conditioning unit will need by using a sizing chart found on the internet (see Resources section). For example, if your home was 1,000 square feet you would need 19,500 Btu.
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3
Adjust your estimate for insulation. For each room that is not below an insulated ceiling, add 4,000 Btu.
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4
Adjust your estimate for room purpose. Each kitchen adds 4,000 Btu. For rooms that have more than two people living in them, add 600 Btu for each extra person beyond the second. For example, if you have three people living in a room add 600 Btu. If a room has four people living in it, you would add 1,200 Btu.
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Adjust for sunlight. If a room is shaded, subtract 1,000 Btu. If a room receives significant sunlight, calculate the amount of Btu required for that room by measuring the room's square footage and then using a room sizing chart (see resource two). Add 10 percent of the room's requirement to your estimate. For example, if you have a 175 square foot room, it would require about 6,000 Btu so you would add 600 Btu to the estimated total in step two.
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Tips & Warnings
Get an air conditioner close to your needed size so it does not have to overwork to meet your demands nor does it switch on and off and waste extra energy.
Energy Star rated AC units are about 14 percent more efficient than AC units without the Energy Star rating.
