Webster Air Conditioning & Heating Knowledebase > Selecting an Air Conditioner

Repair versus Replace

When your cooling system breaks down, you may be faced with the choice of repairing your existing unit or purchasing a new air conditioner. ACU Air focuses on educating its customers so that they themselves can make an informed decision regarding the replacement or the repair of an existing air conditioner. Repairs on an existing unit may be the least expensive immediate option, but may cost the consumer more in the long run. An older system that breaks down once is likely to break down again and it will consume more energy than a newer system. In fact, installing a new, energy efficient system can pay for itself over time. However, there are times when simple repairs can prolong the life of an air conditioner so that immediate replacement is not the most sensible option.

Selecting a Unit

It's a purchase you make perhaps once in ten years. You're concerned about efficiency and comfort, but how do you know which brand and model to choose. Understanding the standard ratings applied to air conditioners can help.

R22 versus R410A Based Equipment

If you have not replaced your air conditioning system recently, your condenser and evaporator coil probably use R22 refrigerant (commonly referred to by the brand name Freon) to cool your home or place of business. The United States has prohibited the production and import of R22 based air conditioning equipment effective January 1, 2010. If you replace your equipment after that date, you will have to purchase R410 refrigerant (commonly referred to by the brand name Puron) based equipment. If you need to replace your air conditioning unit before the ban takes effect, you have the choice of purchasing R22 based or R410A air conditioner.

Efficiency Ratings

In general, the more efficient the unit, the more it will cost initially. However, more efficient equipment will actually save you money over time as it requires less fuel to cool your home. Cooling efficiency for air conditioners is indicated by a SEER (Seasonal Energy Effiency Rating): the higher the number, the greater the efficiency. In 1992, 10 SEER was the minimum rating for units installed in new homes. The Department of Energy has since set a new minimum standard of 13 SEER for air conditioners manufactured on or after January 23, 2006. 13 SEER equipment is approximately thirty-percent more efficient to operate than 10 SEER equipment. For even greater energy savings, consider 14 SEER, 15 SEER, or higher equipment.

Sound Rating Numbers (SRN)

Depending on its location, a noisy condensing unit may destroy the peace and quiet of your garden or may be a sound nuisance when you're indoors. The sound level of outdoor units is measured in bels, on a scale from 0 (barely perceptible) to 13 (the loudest). Most air conditioners operate at 8 to 9 bels. This may not sound like a wide range, until you learn that a 9-bel unit is 10 times louder than an 8-bel unit. In other words, one 9-bel unit makes as much noise as 10 8-bel units put together. As a general rule, R410A condensers are quieter than R22 units. Because R410A operates under far higher pressure than R22, the R410A units are constructed with a stronger, thicker shell, which reduces the noise and vibrations created by the compressor. One of the quietest units currently on the market is Carrier's Performance Series condenser, registering 6.7 to 6.9 bels, thanks to its patented Silencer System II. The Performance Series exceeds industry standards by employing a specialized motor mount, a compressor sound blanket, forward swept fan blades, a laminated sound elimination compressor mounting plate, and a silencer airflow baffle.

Comfort Features

Some air conditioners come with additional features that provide greater comfort. Two-speed units run on low-speed (using about 50% of the energy) 80% of the time. They use fewer on/off cycles and produce fewer drafts and much small temperature swings.

Size

In order to achieve comfortable cooling and dehumidification, the air conditioning system must be correctly sized. Traditionally, central air conditioning units have been sized in tons, with one ton cooling 12,000 BTUs per hour. As a general rule of thumb, you need 12,000 BTUs or 1 Ton of cooling for each 500 square feet of living space. This ratio assumes that the space you are cooling has standard 8 foot ceilings, that windows make up less than twenty percent of southern facing walls, that your windows have drapes or blinds and that you close them during the heat of the day, and that your walls and attic are insulated. In the past, you could divide the square footage of your living space by 500 to determine the number of tons you need. However, manufacturers have re-engineered their equipment and most new 13 SEER equipment now cools fewer than 12,000 BTUs per advertised ton. Consequently, if you need to replace your existing equipment, you may have to buy a larger unit (more tons) than your present unit, in order to get the same amount of cooling. To insure that you purchase the right equipment, you will need an experienced air conditioning technician to visit your residence or business, run a heat load, and identify the size and model of equipment which will best meet your needs.

Note that when it comes to air conditioning equipment, bigger is not always better. An over size unit will lower the temperature of the living space too quickly and will shut off before it has adequately dehumidified the air. Excessive humidity facilitates the growth of mold and mildew.