If you live in a hot climate, you may benefit from a higher SEER cooling unit. If the cold outlasts the warm weather and you have above average fuel costs, you may need a higher AFUE furnace.

SEER stands for Seasonal Energy Efficiency Ratio and applies to central air conditioners and heat pumps. The minimum set by the Department of Energy is 13 SEER and for Energy Star, 14 SEER. The higher the SEER, the greater the energy economy.

AFUE stands for Annual Fuel Utilization Efficiency and applies to heating products. The minimum set by the Department of Energy is 78% AFUE and for Energy Star, 90% AFUE. The higher the AFUE, the greater the energy economy.

HSPF stands for Heating Seasonal Performance Factor and measures heat pump efficiency. The minimum set by the Department of Energy is 6.8 HSPF and for Energy Star, 8 HSPF. The higher the HSPF, the greater the energy economy.

In a central air conditioning system, a refrigerant circulates through a loop of copper tubing that runs between an outdoor unit—the Condenser—and an indoor unit the Air Handler. As the refrigerant travels between the two units, it absorbs heat from the room and releases it outside. The compressor in the condenser is the “engine” that pumps the refrigerant around the loop. The blower in the air handler pushes room air past the evaporator coil which cools the air and causes it to release its moisture, which drops into a drain pan and is piped away.

Central air conditioning can be combined with a forced-air furnace or can be packaged in with a hot water coil (called a hydroair unit) - both share the same blower and ductwork. In all cases, the system is provided with an air filter to remove dust, hair, and lint.

Air conditioners are powered by electricity. Proper maintenance and service can help reduce the high cost of keeping your house cool. Keeping your filter clean prevents a dirty evaporator coil. If your system has the standard 1 inch thick filter, it should be checked every month when air conditioning or heating are in use to be sure it is clean. Deeper pleated “high efficiency” filters have a larger capacity and should be checked before the heating and/or cooling season and replaced if necessary.

Outdoors, keep leaves, mulch and debris away from the base of the condenser.

Central air conditioning systems perform two functions, they remove humidity from the air and they cool the air. When a system is first turned on in a hot house, the first thing the system works on is removing the humidity – this is called the “latent load”. Once the humidity starts to drop, the temperature of the air will start to lower – this is called the “sensible load”. Lowering both the humidity and temperature provide comfort.

Central air conditioners work differently than window units. Central air drops the air temperature between 16-20 degrees each pass through the air handler. It takes a while for the whole house to drop down from elevated levels when a central air system begins to run. A window unit blows out very cold air from a single point so it is easy to cool one room in a hurry but it doesn’t travel far.

A closely sized central system may only drop the temperature indoors one degree per hour on a very hot humid day. Oversizing the unit will help drop the temperature more quickly on these days but when the outdoor temperatures are more mild, an oversized unit won’t run often and the air will be cool but humid – not a comfortable feeling.

The proper way to operate a central air system is to button up the house as tightly as possible and keep it that way. This will prevent humidity from leaking in and burdening the system with latent load. Raising the internal temperature is better from an operating efficiency standpoint. Keep the house closed and raise the thermostat so the unit only operates for short periods, thereby keeping the humidity under control. Continuously opening and closing up the house will force the system to remove humidity repeatedly.