Buying the right size A/C

When you buy an air conditioner it is important to ask what size you need. Many consumers only take into consideration the cost, brand and model when they make this large purchase.  When choosing what size will work best for you, take into consideration ceiling height, insulation thickness and what tonnage will best serve your needs. Tonnage does not refer to the weight of the air conditioner, but is a measure of the system’s ability to cool. One ton means that the A/C can cool 12,000 BTU’s an hour. BTU stands for “British Thermal Unit”. It is the amount of energy needed to heat or cool one pound of water by one degree Fahrenheit.  An A/C which is 1 ton has the ability to cool 12,000 pounds of water by one degree every hour. A 2 ton central A/C can cool 24,000BTU’s an hour. It may sound complicated but it isn’t really!

Home A/C’s are normally between 1 to 5 tons. 5

tons and over are normally for commercial type situations. If your house is large enough to warrant a 5 ton unit, you may consider installing multiple units. This way, if one unit fails, the other will still be working. It is important to get a system that fits your home correctly. If a unit is too big, you will pay for it via your increased power bill! Being energy efficient is more important than having an A/C system that is too big for your house. A/C’s run in cycles and should slowly and steadily cool your house off, rather than quickly, which will result in too much energy being used. If your system is too large it will continuously shut on and off. This is not energy efficient.  If the unit is too small it will have the opposite effect and run nonstop trying to cool your house down. It will work overtime and run up your power bill. The goal is a system sized just right for your house that goes through the correct amount of cycles and is efficient at its job, while being energy efficient. Your A/C technician, or salesperson will be able to help you calculate what size you need. They may do a room by room calculation and take ducting into consideration when making their decision. Remember to always get a couple of estimates and compare what sizes contractors suggest.