June 2001 Edition

 How To Buy A Furnace & A/C

Our home inspector said our twenty year old furnace is on its last leg and the air conditioner can’t be far behind. Would you give us some idea on how to purchase an energy efficient replacement?
Your inspector was probably right about the condition of the system. Around every 15 years in the life of a home the roof shingles, heating system, air conditioning system and water heater will need replacing. By choosing an energy efficient replacement, you can save a great deal of money over the life of the system.


The Department of Energy Federal Energy Management Program (FEMP) requires all manufacturers to post a big yellow label on all new products which is an "ENERGYGUIDE". The label shows how much energy the product will use over a one year period and the estimated annual energy cost. This label will allow you to compare the energy efficiency of the product you are buying with the average of all of the others.
Gas furnaces are rated by "AFUE" (Annual Fuel Utilization Efficiency) which is a measure of heating efficiency on an annual basis. The DOE test procedure defines AFUE as the heat transferred to the conditioned space divided by the fuel energy supplied.
 The minimum AFUE you should be looking for is 90% efficient. Available units with an AFUE of 97% are cost effective if the price is no more than $900.00 above the price of the base model. The difference in annual energy cost of a 70,000 BTU/H 90% unit and a 97% unit probably will be under $100.00.
 Oversizing of furnaces, besides raising purchase cost, will result in weaker energy efficiency due to excessive on-off cycling. The required furnace capacity should be determined based on the Air Conditioning Contractors of America (ACCA) Manual J, a load calculation guide for residential heating and air conditioning, and Manual S, a sizing guide for heating and cooling equipment.
 The DOE recommends leaving your furnace off during unoccupied hours or using a set-back thermostat to minimize unnecessary operation of the unit.
Each air conditioner has an energy-efficiency rating that lists how many Btu per hour are removed for each watt of power it draws. For central air conditioners, it is the Seasonal Energy Efficiency Ratio, or "SEER".


These ratings are posted on an Energy Guide Label, which must be conspicuously attached to all new air conditioners. Many air conditioner manufacturers are participants in the voluntary EnergyStar labeling program. EnergyStar-labeled appliances mean that they have high EER and SEER ratings.
In general, new air conditioners with higher SEER ratings sport higher price tags. However, the higher initial cost of an energy-efficient model will be repaid to you several times during its life span. Your utility company may encourage the purchase of a more efficient air conditioner by rebating some or all of the price difference. Buy the most efficient air conditioner you can afford, especially if you use (or think you will use) an air conditioner frequently and/or if your electricity rates are high.
 National minimum standards for central air conditioners require a SEER of 10.0 for split-systems. But you do not need to settle for the minimum standard—there is a wide selection of units with SEER ratings reaching nearly 17.0.
 Before 1979, the SEER ratings of central air conditioners ranged from 4.5 to 8.0. Replacing a 1970s-era central air conditioner with a SEER of 6 with a new unit having a SEER of 12 will cut your air conditioning costs in half.
 Oversizing of air conditioners, besides raising purchase cost, will result in reduced energy efficiency, poorer humidity control and shorter product life, all due to excessive on-off cycling. The required air conditioning capacity should be determined based on the referenced ACCA calculations procedure.
Heat pumps are rated the same as air conditioners with SEER ratings. You may also find HSPF (Heating Seasonal Performance Factors).
Heat pumps operate very inefficiently at sub-freezing temperatures, so should be avoided as stand alone heating systems in cold climates. However, they will always offer energy savings over straight electric resistance heating coupled with central air conditioning. Most systems come with resistance back-up that takes over when the heat pump cannot pull enough heat out of the outside air. Some of the newer units come with gas back-up which, up until last year, was less expensive to operate than resistant heating.
 Sealing Ducts Is Important
 An enormous waste of energy occurs when cooled air escapes from supply ducts or when hot attic air leaks into return ducts. Recent studies indicate that 10% to 30% of the conditioned air in an average central air conditioning system escapes from the ducts.
 For central air conditioning to be efficient, ducts must be airtight. Hiring a competent professional service technician to detect and correct duct leaks is a good investment, since leaky ducts may be difficult to find without experience and test equipment. Ducts must be sealed with duct "mastic." The old standby of duct tape is ineffective for sealing ducts.

 Source: United States Department of Energy



Source List:

American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE)
1791 Tullie Circle, N.E.
Atlanta, GA 30329, (404) 636-8400, Fax: (404) 321-5478

 Air Conditioning Contractors of America (ACCA)
1513 16th Street NW
Washington, DC 20036
(202) 483-9370, Fax: (202) 234-4721

 EnergyStar® Program
e-mail: info@energystar.gov,


The Energy Efficiency and Renewable Energy Clearinghouse (EREC)
PO Box 3048
Merrifield, VA 22116
(800) 363-3732 (800-DOE-EREC), Fax: (703) 893-0400
E-mail: doe.erec@nciinc.com

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., 3697 Habersham Lane, Duluth, Georgia 30096. 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

"I believe that friends are quiet angels who lift us to our feet when our wings have trouble remembering how to fly."

- Unknown

 A Tip Of The Hat To:

Debbie Scott

Prudential Atlanta Realty

4390 Pleasant Hill Road

Duluth, Georgia 30096

**** Thank You****