HomeownerEducational: A-M

Air Conditioning & Heating

Air Conditioning & Heating

Efficiency Ratings

Gas furnaces. Gas furnace efficiency, or AFUE, indicates the percentage of fuel burned that is converted into heat for the home. As AFUE increases, the cost to heat a home goes down. A 95 percent AFUE furnace delivers $0.95 of heat for every $1.00 spent on fuel. US Department of Energy (DOE) mandates currently require a minimum of 80 percent AFUE, which delivers $0.80 of heat for every $1.00.

Heat pumps and air conditioners. The SEER rating is the primary efficiency rating of both heat pumps and air conditioners. A higher SEER rating means higher efficiency and lower power bills. As of July 2016, the DOE adopted a regional efficiency standard, which requires a minimum of 14 SEER in southern regions and 13 SEER in northern regions. As a comparison, a 15-year-old air conditioning unit would likely have a SEER rating of around 6. Replacing a 15-year-old unit with a modern 13- or 14-SEER-rated unit would cut cooling costs by more than half. Moreover, many homeowners find that new, highly efficient systems quickly pay for themselves through lower power and gas bills and lower maintenance costs.

Increasing Efficiency

Insulation. Insulation helps maintain consistent temperatures and lessens the amount of heat or air conditioning that is needed to provide an ideal temperature. Adding insulation to an inadequately insulated home can substantially reduce energy bills.

Programmable thermostats. Programmable thermostats permit homeowners to set temperatures ahead of time. These thermostats can store unique settings for different times of the day. For instance, in the winter, if no one is home during the day, thermostats can be set to automatically decrease the temperature at which the unit turns on. Later in the day, thermostats can automatically raise temperatures, which will warm the house before homeowners return.

Duct sealing. Duct systems typically leak 30 to 35 percent of the system capacity into unconditioned spaces, such as attics and crawl spaces. Sealing the system will reduce energy costs while increasing the deliverable capacity of your system.

Hydronic heating. Hydronic units, or boilers, heat your home by circulating hot water through tubing in your walls and flooring to produce steady, even heat. Though the cost of installation is greater than a typical forced-air system, a high-efficiency boiler can reduce fuel consumption by up to 40 percent and cut heating costs by as much as 30 percent in the average home.


Sizing a system. Correctly sizing a gas furnace system, air conditioning system, duct system, or heat pump system is extremely important. If the system is too small, it will not adequately control the temperature of the house on especially cold or especially warm days. On the other hand, if the system is too large, it will cycle on and off frequently, resulting in excess noise, lower efficiency, and potentially decreased humidity control. Because the contractor selling the system also sizes it, it is vital to buy your system from a reputable company. Your contractor should reference Manual J, the specific protocol used to calculate the heating and cooling loads of a building, when determining the appropriate size of a system.

Permits. Most cities require contractors to take out building permits when replacing or installing a system to avoid fines and additional repairs. Building permits necessitate an inspector review the completed installation to ensure it meets all relevant safety and building codes.

Resolving Common Issues

Before calling in a contractor, make sure the problem is not one that you can fix yourself. The following are simple problems with quick fixes:

Entire system does not run. A lack of electric power is a common reason that an air conditioning or heating unit will not run. Before calling the experts, reset all circuit breakers or check all fuses in the main electrical panel to ensure the unit has power. If the problem continues, get a professional involved.

Water leaks. One of the primary functions of air conditioning systems is to remove moisture from the home. Depending on the location of your system, water may leak onto your floor or ceiling if the condensate drain line clogs. Attic systems typically have a primary line that drains into your plumbing system and a secondary line that should run to the eave of the house and drain outdoors. If water is running out of that line, it usually means the primary drain is clogged. Removing the clog may fix the problem. See the owner’s manual for specific instructions.

Unit freezes up. Insufficient airflow or not enough refrigerant can cause units to freeze and stop working. If air is not coming out of the vents, check to see if the fan is working. If the fan is running, check the inside unit for signs of ice around the coils. This problem is often caused by a dirty filter or low refrigerant. When the filter is dirty, air cannot pass over the coils, and condensation freezes. To fix this, try replacing the filter. If this does not work, there may be a refrigerant leak. Before calling an expert, turn the unit off, and give the ice time to melt. Until the ice has melted, the technician will not be able to diagnose and fix the problem.

Regular Maintenance

Since many minor air conditioning and heating system problems can lead to other, more expensive repairs, all problems should be resolved promptly. Because small issues often go unnoticed, routine system checkups by an expert are vital. According to some heating and air technicians, half of all emergency service calls could be avoided with routine service. Many companies sell annual maintenance contracts. Routine safety checks on gas systems are especially important; each year, many people in the US die from carbon monoxide poisoning. Regular service can also eliminate the need for a contractor during peak seasons, such as the first hot spell of the summer or cold snap of the fall, when demand is high.

Finding a Contractor

When looking for a contractor to install or repair your HVAC system, keep in mind that a cheaper job or piece of equipment will not necessarily save you money. A low-quality system, installation, or repair can lead to inefficiencies that will result in higher monthly bills and possibly even more repair work later. Most heating and air conditioning contractors provide both installation services and maintenance and repair services. Many offer annual maintenance contracts to inspect and service the system before it breaks. All manufacturers recommend preventative maintenance services be performed at least twice per year.