Air Condintioning System

New Air Conditioning System

Central AC and Heat Pumps

Central air conditioners and air source heat pumps are both widely used in the U.S. and are the best option for maintaining comfort in areas that experience high humidity. Heat pumps are much more efficient than central air conditioners and can be used very effectively both for heating and cooling in southeastern states. Both central AC and air source heat pumps are rated according to seasonal energy efficiency ratio (SEER). This is the cooling output divided by the power input for a hypothetical average U.S. climate. The higher the SEER, the more efficient the air conditioner. To get the best performance and highest efficiency possible from your new Air Conditioning system, consider the following:

• Approved Contractors recommends SEER of at least 14.5 
  In all climates, ACEEE recommends consumers purchase new cooling equipment at the ENERGY STAR level. If you live in a very hot-humid climate, consider the advanced efficiency levels as defined by the Consortium for Energy Efficiency (CEE). Your utility may offer incentives for equipment at these levels. Air conditioners and heat pumps meeting these performance criteria can be found by running a search in the ARI/CEE HVAC Directory.

• Approved Contractors recommends EER of at least 11.6
  This ensures the unit is efficient throughout the year and when it is needed most (on the hottest days). If you live in a hot-dry climate, ACEEE recommends a high SEER (15) but a high EER is less important: 11.5 or 11.6 is adequate. Better yet, consider an evaporative cooler instead.

	Central AC	Air Source Heat Pump	Ground Source Heat Pump
		Click Here For Heating Efficiency Requirements
Market Range Available	13-21 SEER 9-14 EER	13-17 SEER 9-13.5 EER	8.7-20.4 EER
ENERGY STAR	14 SEER 11.5 EER	14 SEER 11.5 EER	Open Loop: 16.2 EER Closed Loop:  14.1 EER DX: 15.0 EER
CEE Tier 2	15 SEER 12.5 EER	15 SEER 12.5 EER	N/A
CEE Advanced Tier 3	16 SEER 13 EER	16 SEER 13 EER

How much money can I expect to save? 
That depends on the price of electricity. You can compare the cost of running a new air conditioner to the cost of running your existing unit using the ENERGY STAR savings calculator. Just enter the price you pay for fuel or electricity from your utility bill. The ENERGY STAR savings calculators are downloadable Excel files; click to download the calculator you would like to use: central air conditioner or heat pump.

• Make sure indoor and outdoor units match 
  The refrigerant controls for new condenser units are incompatible with most pre-2006 indoor units. Installing a new outdoor unit without replacing the indoor unit is likely to result in low efficiency, and may lead to premature failure of the new compressor—the most important component. Ask your contractor or check the CEE Directory of ARI Verified Equipment to make sure that the combination of condenser and indoor unit your contractor has proposed meet the efficiency levels recommended by the Consortium for Energy Efficiency.

• High electrical efficiency
  Ask your contractor about a variable speed air handler, which will improve comfort and efficiency and allow continuous air filtering at minimum energy cost. Never use continuous ventilation when the air conditioner is in use, because it will degrade humidity control.
  
  
  

• Specify R-410 Refrigerant 
  The refrigerant of an air conditioner is essential for operation. For decades residential air conditioners have used Freon (or R-22). Because R-22 released into the atmosphere causes long-term damage, R-22 will not be allowed in new equipment starting in 2010, but will still be available for repairs. Manufacturers have started shifting to R-410a for their products. At present, there is often a price premium for air conditioners with R-410a refrigerant; but if you value environmental protection or expect to remain in your house for many years, you may want to choose the newer R-410a equipment instead of R-22.

Evaporative Coolers

Evaporative coolers, sometimes called swamp coolers, are less common than refrigerated air conditioners, but they are a practical alternative in very dry areas, such as the Southwest. They work by pulling fresh outside air through moist pads where the air is cooled by evaporation.

You can get a direct evaporative cooler, which adds moisture to a house (could be considered a benefit in very dry climates), or an indirect cooler, which does not. For evaporative coolers to do their job, they must be the right size. The cooling capacity of an evaporative cooler is measured not in the amount of heat it can remove (Btu), but in the fan pressure required to circulate the cool air throughout the house, in cubic feet per minute (cfm). A good rule is to figure the cubic square footage of your house and divide by 2. For example, a 1,500 square foot house with 8 foot-high ceilings would require a 6,000 cfm cooler. A listing of leading manufacturers is available from the Evaporative Cooling Institute.

What if I want to get rid of my room air conditioners? You have three options: Ductless mini-split systems are the easiest and most efficient retrofit option for replacing window-mounted room air conditioners. (see next section) Conventional ducted systems may be the least expensive depending on the layout of your house. But because ducts are often responsible for a lot of wasted energy, make sure you hire a contractor who knows about high-efficiency installations. Small diameter high velocity systems are specialty products that use insulated flex ductwork small enough to run through existing walls. The trade-off for the space savings is lower energy efficiency, and an experienced contractor is of utmost importance. Manufacturers include SpacePak and Unico.

Room AC

Room air conditioners are rated only by EER, which is cooling output divided by power consumption. The higher the EER, the more efficient the air conditioner. Federal minimum efficiency standards for room air conditioners were revised in October, 2000; ENERGY STAR requirements exceed the federal standards by 10% or more. Room air conditioners are sized to cool just one room, so a number of them may be required for a whole house. Individual units will cost less to buy than central systems.

• Approved Contractors recommends an EER of at least 10.8. Check the ENERGY STAR list to find qualified products.

• It is critical that your window unit is properly sized.
  ENERGY STAR provides a chart to help find the cooling capacity (in Btus) appropriate for your room. Too much capacity and the unit will cycle on and off too often, wasting energy. Too low and the unit will not cool well and will overdry the air. While the ENERGY STAR chart is a good place to start, note that square footage is not the only factor governing cooling capacity. As an example, if your room has a lot of windows exposed to summer sun, has ceilings higher than 8 feet, or is located directly under the attic, your cooling load might be one or two Btu classes HIGHER than the chart suggests.

Ductless Mini-Splits

Mini-split systems can be an attractive retrofit option for room additions and for houses using hydronic heat. Like conventional central air conditioners, mini splits use an outside compressor/condenser and indoor air handling units. The difference is that each room or zone to be cooled has its own air handler. Each indoor unit is connected to the outdoor unit via a conduit carrying the power, refrigerant and condensate lines.

The primary advantage is that, by providing dedicated units to each space, it is easier to meet the varying comfort needs of different rooms. By avoiding the use of ductwork, mini-splits also avoid energy losses associated with central forced-air systems.

The primary disadvantage of mini-splits is cost. They can cost 30% more than a typical central air conditioner of the same size. But, when considering the cost and energy losses associated with installing new central ductwork, buying a ductless mini-split may not be such a bad deal, especially considering the long-term energy savings. Talk with your contractor about what option would be most cost-effective for you.