Even on the hottest and most humid days in the RGV, an energy-efficient air conditioner can keep your home cool, comfortable and energy-smart. The most common type of central air conditioning unit is the “split system.” Commonly in a “split system,” refrigerant circulates between an indoor coil and an outdoor coil. The refrigerant cools the air, dehumidifying it in the process; a blower circulates air through ducts throughout the house. A thermostat maintains the temperature at the setting you select. A variation is the “heat pump” a type of system that functions as heater and air conditioner.
Conventional air conditioning units use an electrical coil or gas furnace to heat your home. Multi-purpose heat pumps can heat or cool your home quietly, efficiently and effectively with the same technology that cools your house. These can come in the form of a split system with or without ductwork. A split system without the use of ductwork is known as a “mini-split”.
Perfect for spaces like add-on rooms where installing ductwork isn’t practical, mini-split systems provide a flexible and efficient heating and cooling solution. Split ductless systems have an outside condenser and compressor, and one or more indoor blower units, called air handlers, mounted high on the wall that distribute air. The indoor and outdoor sections are connected by a thin conduit that houses the power cable, refrigerant tubing, and a condensate drain. Each air handler cools the room in which it’s installed, and you set the temperature with a remote control. Split ductless systems can be more expensive than window air conditioners, and professional installation is recommended. While not technically central air, the cooling they provide can feel like a central air system.
Size & Tonnage
The air conditioner’s cooling capacity, size is measured in British thermal units per hour (Btu/hr.) or in “tons.” One ton of cooling equals 12,000 Btu/hr.
The easiest place to find out the “size” of your unit is to look at the AC unit itself. Go outside to the condensing unit and look for a data plaque mounted to the side. Find the model number. Normally within this string of letters and numerals, you should find an even, two-digit number.
- 18 = 1.5 tons
- 24 = 2 tons
- 30 = 2.5 tons
- 36 = 3 tons
- 42 = 3.5 tons
- 48 = 4 tons
- 60 = 5 tons
This describes how much cooling the unit delivers for each watt of electricity. Efficiency is expressed as the seasonal energy-efficiency rating, or SEER. The minimum SEER for a split system central air conditioner allowed today is 14, so look for units with SEER ratings of 15 or greater. The higher the SEER, the more you can lower your energy costs. How much will you save with a higher SEER unit? Check out this calculator here to compare the difference.
If you’re upgrading your central air, don’t assume you should buy the same-sized system. Any changes you’ve made to improve your home’s energy efficiency, such as upgrading your windows or adding insulation, can reduce your cooling needs. On the other hand, if you’ve added rooms, you might need more cooling.
Programmable thermostats can reduce your cooling costs by about 10 percent. And using a box or ceiling fan, which costs little to run, can make you feel 3° F to 4° F cooler. You can sometimes get an ENERGY rebate if you choose to install a programmable thermostat.