June 2000 Edition

Air Conditioning Basics

Can you explain how the air conditioner works? I always thought it created cold air. Someone told me it doesn’t make cold air at all. 
Air conditioners work by compressing a gas commonly referred to as freon. The gas picks up heat from the inside of the house and then releases it to the outside through the condenser coils. As the refrigerant is allowed to expand in the evaporator coils inside the house, it absorbs heat. The heat causes the refrigerant to change back to a gas before returning to the outside compressor which compresses it again and begins the cycle again.  
The outside air conditioning condenser is pretty ugly. Would it be okay to build a fence around it?
 The air conditioning condenser works by pulling heat out of the house and exhausting it to the outside thru the coils in the condenser. You do not want to block the coils or the unit will not work properly. If you build a fence around it, make sure the fence is a minimum of 24" away from the unit and nothing is closer than 48" above it. 
How do we maintain the outside air conditioning condenser and would shading it from the sun help? 
It is important to protect the coils from damage from lawn mowers and weed eaters. The fins on the coils exhaust the heat and when the fins are damaged, the efficiency of the unit is reduced. Keep the coils clean by washing dirt and debris out with a garden hose or high pressure sprayer. TSP or Tri Sodium Phosphate is a good cleaner to use. Just spray it on with a garden sprayer and then rinse.  
Shading the unit would probably help the efficiency some, but it is more important not to block the air around the coils. 
Should we run the air conditioning during the winter to keep it system working properly?
You should not run the air conditioning if the outside temperature is below 65 degrees unless you have a heat pump. Turning on the air conditioner during the winter can damage the compressor since the gas is in a liquid form instead of a gas due to the cold weather. Some manufacturers require the temperature to be 65 degrees for a minimum of 12 hours before turning on the air conditioning to insure the refrigerant is in a gas state. Running the unit in the winter will not extend the life or keep the parts working properly.
Will using ceiling fans with the air conditioning help save money?
Cold conditioned air stays close to the floor where the people are. By using ceiling fans you will mix the warmer ceiling air with the cooler floor air. The result is a slight increase in the temperature.
The ceiling fans do give off a cool breeze. It would help to raise the thermostat temperature and then use the fans. This would save energy.
If you have a whole house fan, running the fan will cost about a fourth of the cost of running the air conditioner. In the early mornings and late evenings when the outdoor temperature drops below the indoor temperature, turn off the air conditioning, open the windows and turn on the fan. This will pull the cooler outside air inside.
What is the most effective way to reduce my air conditioner bills in the summer?
The most effective way is to set your thermostat as high as possible to reduce the amount of time the air conditioning is running. Georgia Power recommends setting the thermostat no cooler than 78 degrees. A programmable thermostat will help conserve energy by raising the temperature slightly during the day when no one is home, and then lowering the temperature right before you come home. It is not a good idea to turn the air conditioning off during the day and then back on when you come home. This actually take more energy to play "catch up".
Most homes have major heat gain through all of the windows. As much as 30 percent of you air conditioning bills go towards cooling this heat. By adding blinds or thermal curtains, you can reduce the heat gain. Close them during the day to reflect the sunlight.
Other options would include adding solar films to the glass. Solar films are plastic sheets that you install over the glass to reflect the sunlight. Some solar films are do-it-yourself projects but most are installed by professionals.
 Still another option would be solar screens. Solar screens are fiberglass screens similar to insect screens. They install on the outside of the windows and block the sunlight from reaching the windows.
 The most effective way is of course the most expensive way. You can replace the windows with high efficiency insulated glass windows with low emissivity glass. Low-e glass can reflect up to 70% of the heat from the sun.
What is the best brand of air conditioner to buy and should you replace the furnace at the same time?
 According to Dennis Creech, Jackson EMC Energy Expert, "The name on the equipment is not nearly as important as the quality of the installation. First consider the unit’s size. Many air conditioners are too big. Bigger units cost more to buy and operate, and don’t adequately remove humidity. Have the contractor do a computer calculation to determine the proper size.
 If you are replacing the air conditioner’s outdoor compressor unit, make certain that the model selected matches the indoor equipment. Installing a new, high efficiency outdoor unit without upgrading the indoor equipment may not provide significant savings.
 Don’t install a new air conditioner without repairing the ductwork. Many homes loose more than 20 percent of total heating and cooling due to leaks in the ductwork. Seal the ductwork in your home with mastic and insulate both the supply and return ductwork."
 What is the most important thing to do to keep my system working properly?
 The most important is to keep the system clean. You do this by replacing or cleaning your furnace filter when it gets dirty. A dirty filter will restrict the air flow and increase the operating cost of the system. Check your filter monthly and replace or clean it if it is covered with dust. The blue fiberglass filters are 3% to 5% efficient, which means 95% to 97% percent of all dust goes right through the filter. Filters come in all types and efficiencies. Some of the more efficient filters can actually block air flow and are not good for your system. To check the air flow through your filter, slightly open the blower door while the blower is running and see if the fan speed increases. If it does, the filter is restricting the air flow and a different filer is needed. If you have problems with allergies or pollen, filters up to a 97% efficiency are available. For more information on filters check with your building supply home center or a heating and air conditioning contractor.
 Next, have the entire system serviced every spring and fall. Servicing will include oiling the blower and the system tuned up before it develops a problem. Be sure to have the inside and outdoor coils cleaned yearly by a professional. This will insure the system is running at its peak efficiency. Most companies offer service contracts and will offer discounts if serviced during slower periods.

 If you have a question, change of address, comment, home tip or would like to send Home Tips to your clients, send your letter to Home Tips, Christian Building Inspectors, Inc., 1003 Star Court, Norcross, Georgia 30093. You can E-Mail your questions to us at rodharrison@christianbuildinginspectors.com. We reserve the right to edit questions for length.

Quote Of The Month

"The feeling of being hurried is not usually the result of living a full life and having no time. It is, rather, born of a vague fear that we are wasting our life"

- Eric Hoffer

A Tip Of The Hat To:

Tammy Park

Re/Max North Atlanta International Office

3510 Shallowford Road

Atlanta, Georgia 30341