Special Report #1:
How to buy an energy-efficient cooling and heating system
Decisions, Decisions, Decisions…..
Your household budget. The comfort of your home. The environment. Safety. What do these things have in common? If you are in the market for a new central air conditioner, furnace or heat pump you are about to make some choices that will have a significant, long-lasting impact on all of them.
If you are thinking about buying a new central air conditioner or heat pump, you must choose from literally thousands of products. You must also select one of seemingly countless heating and cooling contractors in New Jersey to install your new system.
Your choices are extremely important. Heating and cooling are typically the two largest components of your annual energy bill, accounting for well over half of all household energy consumption. Recent studies in New Jersey and other parts of the country suggest that new central air conditioners and heat pumps usually just meet minimum government efficiency standards, are often over-sized and installed improperly, and are often hooked up to duct systems that do not allow adequate airflow and leak cooled or heated air to the outdoors. As a result, the average new system is estimated to consume twice as much energy as necessary. That could mean hundreds of dollars a year of unnecessary household energy expenditures. It also means a lot more of the pollution that causes smog, acid rain, global warming, and other environmental problems. Just as importantly, it can lead to comfort problems in your home, higher equipment maintenance costs, and a shorter life for the equipment you have purchased.
A Little Knowledge Can Go a Long Way
You don’t need to understand everything about heating and cooling systems to make an informed decision about what to buy and who to buy it from. However, it does help to understand a few of the basics about the critical decisions you must make and some of the pitfalls you may encounter:
·Energy efficiency ratings. Central air conditioners and heat pumps are both rated by SEER, which stands for Seasonal Energy Efficiency Ratio. SEER is a measure of how efficiently an air conditioner will operate during the summer. Under current law, new air conditioners and heat pumps must have a SEER rating of at least 13. Most equipment sold in New Jersey just meets this minimum requirement. However, all major manufacturers produce equipment rated at SEER 15 or higher which is at least 20% more efficient.
Heat pumps also have an HSPF (Heating Season Performance Factor) rating. HSPF is a measure of average operating efficiency in heating mode during the winter. Under federal law, all new heat pumps must have an HSPF of at least 6.8. Most heat pumps sold today have HSPFs that are close to this minimum requirement. However, all major manufacturers produce models with HSPFs of 8.0 or higher which are at least 15% more efficient.
Furnaces are rated by AFUE, which stands for Annual Fuel Utilization Efficiency. There are two basic families of furnaces – 80% and 90+%. Technology in this area is changing rapidly and includes things like modulating gas valves that allow the furnace to closely match the heating demands of your home, as well as variable drive blowers that can deliver more accurate airflow as heating and cooling demands change.
·Indoor and Outdoor Components. Most central air conditioners and heat pumps have both outdoor components (the condenser) and indoor components (evaporator coils and blowers). Some contractors will suggest that you replace only the outdoor unit. However, these two components are designed by manufacturers to work together. If a new compressor is matched to an old indoor coil that it was not designed to work with, your system will not operate efficiently. In fact, most manufacturers are anticipating an increase in compressor failures because of this practice.
·Equipment Sizing. The Air Conditioning Contractors of America (ACCA) has developed guidelines, known as Manual J, for sizing central air conditioners and heat pumps. These guidelines are designed to keep your home cool and comfortable throughout the summer while operating your air conditioner efficiently. However, studies in New Jersey and elsewhere show that most central air conditioners are oversized, typically one ton (12,000 BTUs) larger than would be suggested by Manual J calculations. Some people mistakenly think “bigger is better”. Others want to ensure that the house will be cool under the most extreme circumstances. However, it is a mistake to size your air conditioner for extreme situations. If you do, you will pay a steep price for the rest of the summer. Consider the following:
An oversized air conditioner will run up your electric bill. Air conditioners operate more efficiently the longer they run continuously. An oversized unit will repeatedly turn itself “on” and “off” during most of the summer.
An oversized air conditioner will make your home feel clammy through most of the summer. Because it will run for only short periods at a time, the indoor coil will never get cold enough to remove moisture from the air.
Oversized air conditioners are noisier. The bigger the air conditioner, the faster the air rushes through ducts and grilles. Often the grilles are not designed for larger units so the noise will get even louder as the air forces its way through small openings.
Oversized air conditioners will need more maintenance and will not last as long as properly sized units. Because it will turn “on” and “off” too frequently throughout the summer, an oversized unit is likely to suffer greater stress than a properly sized unit.
Oversized air conditioners cost more. Not surprisingly, larger air conditioners cost more than smaller ones. A recent study in California suggested that customers paid an average of more than $600 for an extra ton (12,000 BTUs) of cooling capacity.
- Location. The outdoor unit (compressor) of the central air conditioner or heat pump is doing most of the hard work, keeping your home cool or warm by condensing the refrigerant and pumping it through the refrigerant lines. This is a stressful process that generates heat that the unit needs to release. This stress is intensified if the unit is receiving additional heat from direct sunlight or is unable to release heat efficiently because debris or plants around it prevent good air circulation.
- Refrigerant and Air Flow over the Indoor Coils. Air conditioners cool your home by passing air over coils that are filled with cold refrigerant (commonly called freon). Manufacturers always specify the amount of refrigerant that should be in the system. They also specify the volume of air that is supposed to pass over the refrigerant-filled coils. If your contractor has put the wrong amount of refrigerant in the lines or failed to ensure that the correct volume of air is flowing over the coils, the system will not operate efficiently. A majority of the new central air conditioners tested in a recent New Jersey study had improper air flow rates; studies in other parts of the country suggest that improper refrigerant levels are also common. Such mistakes lead to higher energy bills, higher maintenance costs, and shorter equipment life.
- Duct leaks. Ducts are often the forgotten half of a home’s cooling and heating system. They are responsible for distributing the cool air generated by your air conditioner throughout the home, so it is critical that they are in good condition. Recent studies in New Jersey and elsewhere have shown that ducts often leak 20% of the air that flows through them directly to the outdoors. That is pure waste that you are paying for on your utility bills. These leaks are usually not easy to see. However, a well-trained contractor with proper diagnostic equipment can find these leaks and repair them for you.
- Duct Insulation. Ducts that are located in attics, crawlspaces or unconditioned basements can lose a great deal of energy even if they are not leaky. If there is only a thin sheet of metal to separate the cool air on the inside of the duct from the warm air on the outside of the duct, energy will be lost through conduction, much like it is lost through single pane windows.
- Thermostats. During the summer months, when you are away from the home for extended periods of time, you may want to make energy-saving adjustments to the thermostat setting by raising the desired temperature. Also, during the winter months, lowering your thermostat setting when you are away or while sleeping can save a great deal of energy without affecting your comfort. Programmable thermostats make this easy by automatically allowing you to set the time of day when you need to cool or heat your homeless.
- Maintenance. Once you have bought your new air conditioner or heat pump, regular maintenance is necessary to keep it operating efficiently. The indoor coils should be kept clean. The outdoor coils should be cleaned annually. The refrigerant charge should be verified. Electrical connections should be tightened, contacts cleaned, and amp draw monitored. Correct airflow across the indoor coils should be verified annually. Discrepancies in any of these areas can head off a potential problem before it becomes a crisis. The air filter should be checked every month year around and changed or cleaned whenever it is dirty.
The bottom-line is that having a good and efficient cooling and heating system is more than just buying a good piece of equipment. It is just as important to make sure that your new purchase is sized and installed correctly. It is also important that the ducts used to distribute cooled air in the summer and heated air in the winter are in good condition, insulated where appropriate, and have had major leakage points sealed. Since contractors are responsible for sizing and installing equipment and can provide assistance in improving the integrity of your ducts, your choice of a contractor is more important than your choice of equipment.