This guide provides important information about AC units. It will help you identify what functions you need and which models are best suited for your lifestyle.
Efficiency: The cost of energy is on the rise and it’s more important than ever to save money on utility bills. AC efficiency is measured by the seasonal energy efficiency ratio (SEER). Modern AC units are very efficient and must, by law, have an SEER of 13 or greater. The higher the SEER, the less energy used to cool your home. A unit with a 20 SEER will use 50 percent less energy than a 10 SEER model does and 25 percent less than a 15 SEER AC. Most air conditioners are in the 14 to 17 SEER range and the most efficient models have ratings in the mid-20s.
Energy Star units must be at least 14.5 SEER, so just because a unit is an Energy Star, doesn’t mean it’s the most efficient choice for your home. The warmer your home climate, the more efficient your unit should be. If your motivation is purely environmental, then you’ll want to buy the most efficient unit you can afford, regardless of your home climate.More efficient models are more expensive, although they will earn their keep through reduced utility bills. If you buy a unit that is too efficient for your climate, it may take up to 10 years to recover the expense of buying a more efficient unit. However, saving money by buying a less-efficient air conditioner in a warm or hot climate will cost you hundreds or even thousands of dollars over the life of the air conditioner.
Performance: Central air conditioners are produced in good/better/best models – or single-stage, two-stage, and modulating air conditioners. Here’s an overview of each:Single-Stage Air Conditioners: These models have a 13 to 16 SEER. Their compressors have just one speed, so they run on full capacity all the time, wasting a great deal of energy. They are more affordable than most units, but you will probably notice temperature fluctuations of several degrees during and between cycles.
Two-Stage Air Conditioners: These units have 16 to 20 SEER and have compressors that run on about 65 percent capacity to maintain a constant temperature. This creates longer, gentler cooling cycles and reduces temperature fluctuation to just one to two degrees that many homeowners don’t notice. These longer cycles remove more humidity and keep the home more comfortable.
Modulating Air Conditioners: These models are also known as variable-capacity air conditioners and have a 20 or higher SEER. Their compressors change the output during the cycle, like cruise control. Modulating units typically run between 40 and 100 percent of capacity to keep the temperature in your home balanced, almost eliminating fluctuations completely. They run at low capacity and remove even more humidity than a two-stage model does. If the thermostat temperature is lowered, the unit can run at 100 percent capacity for quick, effective cooling. These models produce the greatest climate control.
Tips for Choosing your Next Central Air Conditioner: Choose a unit that is appropriate for your climate. Buying one that is more efficient than needed is by no means a bad thing, but it will take longer for you to recover the cost of that unit in your utility bills. The danger comes into play when you don’t buy a unit that is efficient enough, then you will have sky-high energy bills AND be uncomfortable. Highly efficient units with at least an 18 SEER will be a two-stage or modulating model. Sometimes, homeowners who don’t need a high-efficiency model get one anyway because they want enhanced climate control. Don’t skimp out on installation. Use a qualified HVAC contractor you trust to install your new unit. We recommend getting at least three written estimates from local HVAC companies before deciding who will install the unit.