If you want a quick answer to how much air-conditioning power you'll need to effectively chill a 1,300-square-foot area, the answer is 23,000 BTUs per hour. This is the minimum capacity required for a 1,200 to 1,400-square-foot dwelling, according to the government's Energy Star website. The more square feet there are in your home, the more heat you will generate. So if your house has more than 1,300 square feet, you'll need a heater that produces more than 23,000 BTU hours per year to meet your heating needs during the winter months.
The good news is that most homes today are equipped with heating systems that are efficient enough to never need to be replaced. The bad news is that they also tend to be expensive. Heating systems use a lot of electricity, so it's important that you're not wasting any of it. Here are some ways to save on your heating bill without compromising your comfort level:
Swap out your old, broken thermostat for a programmable one. These allow you to set different temperatures in each room of your house, which means you don't have to turn the heat all the way up or down every time you leave a room. They also can help reduce energy consumption by reducing unnecessary temperature changes.
Consider adding insulation. Adding just half an inch of wallboard or ceiling material will reduce your heating bill by 10 percent.
As a general rule, an air conditioner requires 20 Btu for every square foot of living area. To cool a larger or busier space, consider upgrading to a midsized air conditioner rated at 7,000 to 8,500 Btu. A smaller unit will not be able to keep up with the demand of a large room. The size of your air conditioner can also affect its cost: The more cubic feet it can handle at one time, the cheaper it will be. For example, a unit that can blow cooling air through up to a 75-cubic-foot chamber will be less expensive than one limited to 45 cubic feet.
The first thing you should know about sizing an air conditioner is that no matter what type you buy, heat pumps are much more efficient than traditional refrigerators. So even if an air conditioner is a little bigger than you think you'll need, it won't use as many resources as a small unit would. Heat pumps can reach efficiencies of 90% or more.
Secondly, keep in mind that while most air conditioners require some degree of continuous operation to maintain their efficiency, heat pumps operate best when they are switched on and off frequently. So if you plan to go away for a week-end or longer, a heat pump is the perfect choice.
875 square feet 15,000 BTU air conditioners should be sufficient to cool most rooms up to 875 sq. Ft. AC efficiency is measured in British Thermal Units or Btu for short. One Btu is the amount of heat needed to raise 1 pound of water 1 degree Fahrenheit. So, if you want your room to be 10 degrees Fahrenheit, you need 10,000 Btu of heat loss from the room. A common mistake is to think that more Btu means better efficiency-this isn't true as long as the same wattage unit is being used.
The volume of a room is measured in cubic feet and the surface area is usually calculated by multiplying length times width. For example, a room with a height of 12 feet and a width of 24 feet has a volume of 144 cubic feet and an area of 3456 square feet. The larger the room, the more Btu it will take to cool it down comfortably.
The amount of power required to run an air conditioner is called its "capacity factor". This number tells you how much electricity your air conditioner uses per hour. Most air conditioners are designed to run on utility lines at a steady rate of 500 or 600 watts.
2. Determine the appropriate cooling capacity for the size of your space.
|Area To Be Cooled (square feet)||Capacity Needed (BTUs per hour)|
|700 up to 1,000||18,000|
|1,000 up to 1,200||21,000|
|1,200 up to 1,400||23,000|
|1,400 up to 1,500||24,000|
To calculate your AC tonnage requirements, multiply the amount of square feet you're cooling by 25. This is the total amount of BTUs required to properly chill your room. Divide that figure by 12,000 to get the tonnage capacity you'll need in your new air conditioner.
So, if your house is 8,000 square feet and you want to cool it comfortably with a single zone at 50 degrees F outside temperature, you'd need a tonnage rating of 150,000 BTUs or more. Most homes today are way over 100,000 BTU systems, so you can see how expensive these things are. Also remember that you can't really go wrong with the biggest size machine that will fit into your budget.
The other thing you should know about tonnage is that higher numbers mean better efficiency. A system that's rated at 120,000 BTUs will be much more efficient at cooling than one that's only 60,000 BTUs. This means it'll use less electricity overall and last longer too!
Finally, keep in mind that the bigger the room, the harder it is to cool. So if you can afford it, we recommend getting a bigger house instead!
That being said, calculating tonnage isn't exactly easy and there are many other factors involved in choosing an AC unit.
The lowest AC size, with a capacity of 9,000 BTU, can chill and heat areas up to 350 square feet. Because of its modest size, this is an excellent alternative for people looking for the smallest mini-split AC for their home or workplace.
The largest system, with a capacity of 14,400 BTU, can cool or heat rooms up to 3,500 square feet. It's big enough to handle large spaces like offices or warehouses but also small enough to fit in homes too. This type of system is best for larger buildings where space is not an issue.
Both types of systems come in air handlers that use either electric motors or rotational pumps to move refrigerant through the system. The choice between these two types of motors is based on how much energy they can supply while still maintaining sufficient cooling capacity. If your building uses a lot of electricity, go with an air handler that uses an electric motor; if not, consider one that uses a rotational pump.
Both air handlers are designed to distribute refrigerant throughout the unit by using fans to pull in outside air when necessary. This prevents the need for internal by-pass ducts which can be expensive. However, some manufacturers do offer optional bypass units that will direct warm air from inside the house out through the main return line if you choose.
Size and Ceiling Height. Obviously, a smaller area room or house with shorter lengths and widths uses fewer BTUs to cool or heat...
|Area To Be Cooled (square feet)||Capacity Needed (BTUs per hour)|
|100 to 150||5,000|
|150 to 250||6,000|
|250 to 300||7,000|
|300 to 350||8,000|