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Central Heating and Cooling Systems

When it comes to saving on your utility bills, a great place to start is learning the most you can about your heating, ventilating, and air conditioning (HVAC) system. According to the U.S. Department of Energy, as much as half of the energy used in your home goes to heating and cooling. That's why it's critical to look for opportunities to improve the efficiency of these systems.

Here are a few strategies homeowners can consider:

1. Replace old or failing mechanical equipment. If your heating or cooling equipment is more than 10 years old, needs expensive repairs, or no longer keeps you comfortable, it may be time to replace it.

When replacing, look for performance certified equipment, which guarantees you that the manufacturers' claims of energy efficiency performance are accurate. You can search the free AHRI Directory of Certified Product Performance to find certified HVAC equipment and compare the efficiency ratings of different models.

When replacing cooling and heating systems, it is important to understand how their energy efficiency is determined. Learn about SEER as an energy efficiency rating for central air conditioning and air source heat pump systems.

2. Work with a qualified installer. Make sure that you use a NATE-certified technician who will properly match, properly size and properly install the equipment in your home. Your contractor should determine the right size for your equipment using the ACCA/ANSI Manual J sizing calculation tool, which considers specific attributes about your home.

It is important that the duct work be installed by a qualified HVAC technician. Otherwise, poorly installed duct work can result in poor system performance and higher than expected utility bills. A qualified technician will size the duct system according to ACCA Manual D calculation procedures (or substantially equivalent).

3. Properly seal and insulate. Sealing and insulating can reduce your total energy use by more than 20 percent. Focus first on ducts that run through unconditioned space such as your garage or attic, and seal ducts with mastic or foil-backed tape. After sealing, insulate the ducts by wrapping them in insulation.

Make sure your home has adequate insulation. A well-insulated home helps reduce the load on your HVAC system. The DOE recommends minimum insulation levels for each part of the home, based on your climate. This information can be found on the ENERGY STAR website.

4. Install a programmable thermostat. According to the Environmental Protection Agency (EPA), a programmable thermostat can save you about $150 a year in energy costs if it is properly used. It is recommended for people who are away from home during set times of the day during the week.

To increase your energy savings, the EPA recommends that you:

  • Keep the thermostat set at energy-saving temperatures for long periods of time, such as during the day when no one is home and through the night.
  • Resist the urge to override the pre-programmed settings. Every time you do, you use more energy and may end up paying more on your energy bill.
  • Set the "hold" button at a constant energy-saving temperature when going away for the weekend or on vacation.
  • Install your thermostat away from heating or cooling registers, appliances, lighting, doorways, skylights, and windows, and areas that receive direct sunlight or drafts. Interior walls are best.
  • If you have a heat pump, you may need a special programmable thermostat to maximize your energy savings year-round. Talk to your retailer or contractor for the details before selecting your thermostat.

5. Be sure to have your equipment regularly maintained.

  • Check the filter and change it if it's dirty, or according to the manufacturer's recommendation. Regularly changing the filter keeps dust from collecting on the evaporator coil fins. Keeping your filter clean also can cut energy consumption 5 percent to 15 percent. Turn off the power to the furnace before pulling the filter out so the blower doesn't come on and blow dust throughout the system. Be sure to position the filter according to the manufacturer's instructions.
  • Clear away debris such as leaves, grass, weeds and plants that block airflow through the outdoor condensing unit, which is the large metal box in your yard next to your home. Anything that collects on the unit's fins will block airflow and reduce its efficiency. Grass clippings thrown by the lawn mower are particularly common offenders.
  • Occasionally clean the outdoor condensing unit by spraying it with a water hose.
  • Check to make sure air conditioning vents inside your home are not obstructed by furniture.
  • Check to see that vents in the house are unobstructed. Air in your home needs to circulate easily through the vents. Your furnace works less when heated air is not blocked and the cooler air can circulate back freely.
  • Set the fan speed on high except in very humid weather. When it's humid, set the speed on low; you will get less cooling, but the air circulation will make it feel cooler.
  • Hire a professional to service your central cooling and heating system. A well-trained technician will find and fix problems in your central cooling and heating system. However, not all service technicians have the same level of training. Look for a technician that is certified by North American Technician Excellence (NATE). Click here to find a NATE-certified technician in your local area.

Be sure to insist that the technician:

  • Check for the correct amount of refrigerant and test for refrigerant leaks.
  • Capture any refrigerant that must be evacuated from the system.
  • Check for and seal duct leakage in central systems.
  • Measure air flow through the evaporator coil.
  • Check the accuracy of the thermostat.
  • Verify the correct electric control sequence and make sure that the heating system and cooling system cannot operate simultaneously.
  • Inspect electric terminals, clean and tighten connections, and apply a non-conductive coating if necessary.
  • Oil motors and check belts for tightness and wear. Loose belts can increase furnace operating time. Replace frayed or cracked belts. Two or three drops of oil in the motor will keep it running smoothly. (Sealed blower motors require no lubrication. If you have questions, check your owner's manual or call a heating professional.)
  • Make sure blower doors are replaced properly. This keeps combustion byproducts such as carbon monoxide separate from the warm air circulated through your home.
  • Check to see that the exhaust flue to the outside is clear of obstructions and in good condition from the furnace to the roof cap with all connections securely fastened. A contractor will check it by removing the flue cap near the furnace and water heater and looking through the flue to the outside. The flue cap needs to be replaced securely. If the furnace or water heater is in an enclosed room or closet, they need to get plenty of air. These appliances need ten cubic feet of air for one cubit foot of natural gas to operate properly. Furnace rooms or closets should have door louvers or vents or a duct directly to the outside to provide sufficient combustion air.