Air Conditioning Efficiency and Sizing
Posted on 20. Feb, 2011 by admin in Air conditioning, HVAC, Services
Today’s central air conditioning systems are much more efficient than 10 years ago. The industry uses a rating called SEER for central systems, which is an acronym for Seasonal Energy Efficiency Ratio. Essentially, a higher SEER rating means the air conditioner uses energy more efficiently. When thermostat settings are kept equal, a higher SEER results in lower monthly utility bills for the homeowner. A central air conditioning unit rated at 13 SEER uses almost a third less electricity than a 10 SEER system.
Some outside A/C units are rated at a range, such as 14/15 SEER, depending on what type of indoor equipment they are paired with. For example, if paired with a manufacturer recommended evaporator coil and a variable speed furnace or variable speed air handler, an outside unit could be rated as a 15 SEER system. Otherwise, the rating would be 14 SEER.
As you might imagine, higher efficiency A/C equipment costs more to build. Why? For one reason, more efficient condensers and evaporators contain more metal in their extra coils. Additionally, to gain higher efficiency, the systems may have more complex technology such as motor speeds and electronics.
If you are buying a new air conditioner, make sure you clearly understand the relationship between higher upfront costs and lower monthly utility bills of the more efficient equipment. The Energy Guide label clearly displays the SEER rating of all new A/C equipment.
Size matters a great deal when purchasing a new air conditioning system.
When it comes to the sizing air conditioners, Bigger is NOT Better. The cooling capacity of an air conditioner is measured in British thermal units per hour (Btu/hr.) or in “tons.” One ton of cooling equals 12,000 Btu/hr. If you get a system that is not big enough in capacity, the system will work too hard and use too much electricity attempting to cool the air. Conversely, if you get a system with too much tonnage, the system will cycle on and off too quickly to condition the air properly. This results in a clammy uncomfortable feeling cold rooms plus extra wear on certain parts of the system.
Air conditioning contractors use a complex process and formula to calculate the size of equipment and design each system. When sizing the air conditioning system, there are a few key factors you need to consider. You must measure the home, measure the windows and doors, measure the insulation in the walls and attic and verify the orientation of the home.
The cooling and heating needs of modern home can be challenging. For example, a high capacity kitchen vent hood can remove so much air from a home that it adds substantially to the cooling or heating load. Homeowners can mitigate this somewhat by minimizing use of the hood on its higher settings during the hottest or coldest months.
Within the U.S., demand for cooling and on air conditioning equipment varies greatly with location. At the extremes, the southernmost zone of the U.S. has approximately 4.8 times as many cooling hours as the northern, or lowest demand zone. Factors that affect the envelope include the R Value of insulation in attic, walls, and (if applicable) under the floors, proper ventilation in the attic, whether or not radiant barriers are present, the type of windows and doors, weather stripping, caulking, and more.
Dan Ulrich
President
Green Way Solutions Heating and Air Conditioning
www.gogreenwayhvac.com
Contact Green Way Solutions? Click here: http://goo.gl/7f4aY
