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
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.
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
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 air flow 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
ÆAn 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.
ÆAn 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.
ÆOversized air conditioners are noisier. The bigger the air conditioner, the faster 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.
ÆOversized 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.
ÆOversized air conditioners cost more. Not surprisingly, larger air conditioners cost more than smaller ones. A recent study in
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.