The correct size air conditioner and heating system reduces running costs, maintenance and energy use. It also increases the overall comfort of the home or office. Proper air conditioning – whether cooling or heating – is like the Goldilocks story…the sizing needs to be just right for the job.
Larger units are bigger, more expensive and designed to push greater amounts of air to heat and cool bigger spaces – leading to longer fan run times and higher pressure airflow. When equipment is oversize, it increases the initial purchase and installation costs while decreasing overall efficiency. The higher pressure air can also cause damage and additional maintenance needs for ducts and other equipment.
Similarly, if a unit is too small for the area in which it is operating, initial installation may be lower but overall running costs, energy use and maintenance will increase. The fan on the unit will be running almost constantly in order to meet the demands for the space – creating additional stress on the system components and using copious amounts of energy.
Air conditioner and heater sizes are measured in tons – a reference to the measurement of the equipment’s ability to cool. One ton is the ability to cool 12,000 BTUs (British Thermal Unit) in an hour. A BTU is the amount of energy required to heat or cool one pound of water by one degree Fahrenheit. A one-ton air conditioner can cool 12,000 pounds of water by one degree every hour. Residential units typically run from 1-ton to 5-tons, with increases at half-ton intervals. Anything over 5-tons is considered a commercial unit.
In order to determine the correct size of for your home or office, first determine the square footage for which the unit will be required. Do not include areas such as garages, basements or decks that will not need to be heated or cooled. Next, multiply the square footage by 25 (2,000 sq ft x 25 = 50,000). Then, divide the total by 12,000 (50,000/12,000=4.166). Finally, subtract 0.5 (4.166-0.5=3.6). With this calculation, a 2,000 square foot home would need a 3.5 or 4-ton unit for central conditioning. Your local heating and cooling experts can help you determine variations on requirements based on climate zone – using the most recent Manual J guidelines.
Still have questions about HVAC unit sizing, products or other issues? Contact your local HVAC experts at Hawthorne Plumbing, Heating and Cooling today!