Home Heating and Cooling Systems

Replace your filter

Cooling and heating technologies use more energy than any other system in your home. That means you spend the most money operating these systems. According to the U.S. Department of Energy, 44 percent of a typical home energy bill goes toward heating and cooling.

Air Conditioners and Heaters

Thermostat settings

  • In the summer, set your thermostat at the highest temperature at which you are comfortable.
  • The recommended summer setting is 76 to 78 degrees.
  • The recommended winter setting is 68 degrees.
  • Operating costs change 2 percent for each degree your thermostat is raised or lowered.
  • Set your fan to AUTO, which costs less and provides better humidity control.
  • Use NOVEC's Thermostat Calculator to determine how much you can save.

Keep your filter clean

  • Clean or replace your system’s air filter at least once a month, for the most efficient and economical operation.
  • Dirty filters cause unnecessary strain and can lead to equipment breakdowns.
  • Aluminum mesh filters can be washed. Fiberglass filters must be replaced.

Keep registers and return grills unobstructed

  • Arrange your furniture and drapes to keep all supply registers and return grills free from obstructions so your system can circulate conditioned air to all areas of the home.
  • Vacuum the return grills periodically to remove dust to help ensure good airflow.

Coil care

  • Be sure the maximum amount of air moves across the air conditioner’s coils.
  • Make sure air can flow freely over the inside and outside coils.
  • Shut off power to the unit before cleaning it. Outside, clear away leaves and debris. Inside, clean or replace filters.
  • If you can reach the fan blades, be sure the power is turned off and then dust them – if they’re filled with lint they can’t push as much air.

Avoid excessive use of exhaust fans

  • Turn off the kitchen and bathroom fans as soon as they’ve done their job.
  • Exhaust fans can blow away a houseful of conditioned air.

Don’t make the air conditioner or heater work too hard

  • Keep blinds, curtains and shades closed during the hottest part of the summer day. Direct sunlight increases the load on your cooling system.
  • Place lamps, TVs and other heat-producing devices away from the air conditioner thermostat. Heat from these items could cause the thermostat to read a higher temperature and keep the air conditioner running more than necessary.
  • Leave storm doors and windows closed when the air conditioner is on. That’s money out the window!
  • Close your fireplace flue. Just as it lets hot air escape in the winter, an open flue sucks up cool, conditioned air in the summer.

Leave interior doors and registers open

  • Properly installed systems balance so that sufficient cool air is delivered to and returned from each room.
  • Closing doors and supply registers disrupts this balance, causing your system to run at less than its designed efficiency.
  • Close doors in unused rooms only if there is enough space under the door to allow for sufficient air circulation.

When you’re away

  • Use a programmable thermostat to adjust the temperature at night or when no one is home.
  • If you don’t have a programmable thermostat, you can raise the temperature 5 degrees when leaving home for four hours or longer. When you return, set the temperature back to its normal setting.
  • If you have a heat pump, install a programmable thermostat and configure it to prevent backup heat (auxiliary heat) from turning on.
  • Do not set the thermostat to Emergency Heat unless there is a malfunction with the heat pump. Setting the thermostat to Emergency Heat will increase your electrical usage.

Check the efficiency

  • A quick check of your air conditioner’s efficiency can help you decide whether to call a service professional.
  • Use a household thermometer to measure the temperature of the discharge air from the register (usually in the ceiling or floor) and the temperature of the return air at the return-air grill (usually in a wall).
  • Keep the thermometer in place for five minutes to get an accurate reading.
  • The difference should be from 15 to 20 degrees between the two.
  • If you don’t get this difference, your unit could be low on refrigerant or have leaks, or the filter could simply be dirty.

System maintenance

  • Have your system periodically serviced by a trained technician.
  • Professionals can perform difficult tasks such as pressure testing, recharging the system, checking thermostats, controls and sensors, and repairing or replacing components.
  • Regular maintenance often reveals small problems before they become large, expensive problems.

When to replace your system

  • The average home air conditioning system has a life expectancy of 10 to 15 years, depending on how often it’s used and how well it’s maintained.
  • It’s time to replace your cooling or heating system when the cost of repair equals or outweighs the cost of a new unit, just like most other appliances and large-ticket items.

Attic Fans:

Attic temperatures affect whole house

  • During the summer attic temperatures can reach up to 150 degrees without an attic fan.
  • Extra heat in the attic makes your house hotter, causing your air conditioner to work harder.

How attic fans work

  • Attic fans create a positive airflow through your attic.
  • They blow out super-hot attic air while drawing in cooler outside air.
  • Attic fans can also be equipped with humidity control and used during the winter to remove excess moisture.
  • Attic fans have a thermostat control that cycles the fan on and off as needed.


  • Attic fans are normally mounted on the roof toward the back of the house about two feet down from the peak.
  • An attic fan is installed by cutting a hole in the roof. The fan has a protective cover so rain, snow, and animals cannot get in the attic.
  • Attic fans are waterproof and have flashing that fits in with the shingles.


  • The exact savings obtained with attic fans depends on several factors such as the roof color, if the home is shaded, the amount of insulation, and the efficiency of your cooling system.
  • However, attic fans can help cool the living space below, with the payoff being increased comfort.

When you don’t need an attic fan

  • Most new construction consists of installed soffit and ridge vents, replacing the need for attic fans.
  • Soffit vents allow cool fresh air into your attic.
  • Ridge vents exhaust the hot air.
  • When replacing a roof, you can consider installing soffit and ridge vents, which will eliminate the need for an attic fan.

For more information

To learn more about staying cool and saving money, contact NOVEC's Energy Services Department locally at 703-392-1503, ext. 1503 or via email at energyservices@novec.com.

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