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BTU is an abbreviation for British Thermal Unit. It’s the amount of heat energy required to change the temperature of one pound of water one degree Fahrenheit.

Since no home is typical, there’s only one way to properly size a central air-conditioning system: have a licensed HVAC technician (Heating, Ventilation, and Air Conditioning) do an energy audit of your home before purchasing a unit. That’s what the experts say, anyway. But if you’re just looking to buy a simple window unit, measure the size of your room, and the salesperson at the appliance store should be able to recommend an adequate unit.

-- Mararget Winslow

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