When you’re shopping for a new air conditioner, one of the things you’ll almost certainly be looking for is a high seasonal energy efficiency ratio (SEER). It’s the industry’s metric for expressing an air conditioner’s energy efficiency. Think of it as the HVAC equivalent of the Environmental Protection Agency’s estimated miles-per-gallon figure on the window sticker of a new car.
SEER denotes the ratio between the amount of BTUs of heat extracted from your home versus the amount of electrical energy consumed by the air conditioner. Presently, the federally mandated minimum SEER is 13. The higher the SEER number the better, generally speaking, and high-efficiency units today offer SEER ratings above 20. You’ll find the SEER rating on the bright yellow EnergyGuide label attached to every new unit. It’s there for consumers to use as a quick, at-a-glance method to effectively compare the energy efficiency and performance of a variety of air conditioners.
What you see, you may not get
“Your mileage may vary,” is the caveat that always accompanies miles-per-gallon figures on new vehicles. Similar to the optimistic automobile MPG estimates, the SEER rating you see on the EnergyGuide label is calculated under controlled conditions that may not always reflect typical circumstances. A number of variables can intervene between the laboratory, where the SEER is determined, and your home, where the unit’s actually put to use.
A high SEER rating and other manufacturer’s performance specs are based on assumptions about regular maintenance, local climate and the general operating environment. Chief among these factors, however, is the quality of installation. How your air conditioner is installed — and by whom — are major determinants of what kind of SEER rating your new A/C will actually deliver for years to come in real-world conditions.
Unfortunately, the odds of getting a competent installation seem to be a toss-up. EPA estimates state that half of all HVAC equipment in the U.S. is currently underperforming due to shortfalls in the installation procedure. This results in average performance deficits of as much as 30 percent below manufacturer’s published specs, including the high SEER rating conspicuously displayed on that bright yellow label when the A/C was purchased. What’s worse, the elevated utility costs and low comfort level that result from substandard installation continue indefinitely unless or until the problem is realized and appropriate corrective measures are taken. Often, homeowners just assume they were misled by inaccurate SEER specifications and live with the disappointing results.
Choosing the right contractor
Proper installation begins with the choice of the right HVAC professional to do the job. Today’s high-efficiency units require trained technicians with specialized tools and technology. It’s not a job for the local jack-of-all-trades equipped with nothing more than a pickup truck and a toolbox. The person who comes to your home to install your complex, expensive air conditioning system should have an established presence and track record in the community. He or she should be able to provide recent references and have accreditations from industry organizations such as the American Society of Heating, Refrigeration and Air Conditioning. Competent contractors will usually be authorized dealers for one or more major manufacturers of HVAC equipment, as well, and their field technicians will include factory-trained personnel.
No matter what make you choose, certain basic facts are common to every residential installation. A competent technician will confront and resolve the following issues to make sure you get the high SEER rating you paid for in a new A/C unit:
Airflow’s the lifeblood of any HVAC system. If you’ve scheduled a service call on your existing system, you may have noticed that, no matter what problem you called about, among the first things the technician checked was the condition of the air filter. That’s because the air filter influences airflow, and proper airflow — or the lack of it — is directly related to almost every other system performance factor. It’s one of the first suspects when you’re not receiving the savings you expect from a high SEER rating.
An air conditioner functions by extracting heat energy from warm air moving over the evaporator coil. When this flow of air is below specs for the coil, heat extraction is diminished, and both system performance and your family’s comfort level suffer. Reduced airflow also impacts the coil’s efficiency at removing humidity from the air. Humid air holds more heat than dry air so the home feels warmer than it should even though the thermostat setting is moved lower and lower.
At the installation stage, airflow issues may involve the following factors:
- Undersized ducts: Home construction in past eras often utilized a “one size fits all” approach to ducts in order to standardize building methods. Just because the ductwork in your home was adequate for your existing system doesn’t mean it’s a good match for a new high-efficiency A/C. New equipment may have increased airflow demands to ensure optimal comfort and live up to a high SEER rating.
- Deficient duct design: Ductwork layout impacts airflow due to factors like air friction and thermal loss. To a trained eye, unnecessarily long duct runs, excessive bends and elbows, as well as design that routes ducts through unconditioned zones like attics and crawl spaces where they may be exposed to acute temperatures, may all be red flags. These deficiencies must be addressed when a system is installed.
- Component mismatch: Saving money in the short run by replacing certain parts of the system, such as the outdoor compressor/condenser, while leaving other components like the air handler in place is usually false economy. The indoor and outdoor coils and the air handler blower are components that must operate in harmony, or airflow declines, and a high SEER rating is the casualty. A professional installer will not install incompatible components that actually cost you money and comfort over the long run.
Refrigerant: Not too little, not too much
The refrigerant in your A/C system carries a heavy load. The molecules of heat extracted by the evaporator coil are concentrated by the compressor, then conveyed by refrigerant to the condenser coil, where the heat load is dispersed into outdoor air. The correct level of refrigerant is crucial to proper efficiency and performance. System shortfalls and even damage to expensive components can result from a refrigerant charge above or below specs. New air conditioning units often come from the manufacturer pre-charged with refrigerant for installation. However, field surveys of units in service reveal some disturbing realities:
- A majority of systems in use have a refrigerant charge that does not meet manufacturer’s specifications.
- Most systems have a charge below specs. But some are overcharged by more than 100 percent.
- A/C systems with long refrigerant lines between the evaporator coil and the condenser are more likely to be undercharged.
- Inaccurate measurement of the refrigerant lines is the usual cause of overcharged or undercharged systems at installation.
Undercharging in a newly installed A/C unit can reduce a high SEER rating significantly. In many cases, this deviation is sufficient to wipe out all gains in efficiency and performance provided by upgrading to the new unit in the first place. Proper refrigerant charge by the manufacturer cannot be taken for granted. A professional installer will verify the charge before the installation is finalized and double-check it after the system has been started and test run for a period of time.
Back in the golden era of inexpensive energy, residential ductwork was the neglected stepchild of the HVAC industry. More often than not, ductwork was treated as a cost-cutting opportunity, and lower grade materials and substandard installation were utilized to reduce building expenses. Ducts installed in homes during these times were not engineered or manufactured to last the life of the house. Today, most of that ductwork is quietly deteriorating inside walls and in attics. The owners of those houses are paying the price in increased heating and cooling costs and decreased comfort levels.
Ductwork defects impact performance and efficiency in three ways:
- Leaky supply ducts spill expensive conditioned air into unconditioned zones of the home. Many homeowners are paying increased utility costs by unknowingly heating or cooling an attic or crawl space due to neglected, leaking ducts.
- Return ducts that leak may draw unhealthy, contaminated air into the system from unconditioned areas and circulate it through your entire home.
- The air pressure imbalance resulting from leaky ducts shifts room pressure from neutral to positive or negative pressure. This results in loss of conditioned air that is pushed out of the home through cracks and gaps or the infiltration of outdoor air that is sucked in.
A competent installer will pressure test the ducts first to determine the degree of leakage relative to total system airflow. During the procedure, he’ll use technology designed to pinpoint the exact location of ductwork leaks and seal them. In Sarasota and Bradenton, Aqua Plumbing & Air has kept homeowners comfortable with energy efficient HVAC products for nearly 40 years. Ask us for more advice about getting and maintaining the high SEER rating you expect with your newly installed A/C.