Central air-conditioning
Cool, dehumidify, and filter your home's air
Traditionally, central air-conditioning uses the ductwork connected with the heating system to distribute cooled and conditioned air throughout the space. Traditional central air conditioners cost about $1600, a little less than air source heat pumps, but do not offer the winter heating benefits of air source heat pumps.
Buying the right size unit and choosing a high efficiency model can minimize your installation costs.
Sizing
Air-conditioning equipment should be sized according to guidelines set by the Air-Conditioning Contractors of America or the American Society of Heating, Refrigeration and Air-Conditioning Engineering, Inc. (ASHRAE). The following factors are considered in the sizing calculations:
- Size of area to be cooled
- Amount of insulation in the attic and walls
- Tightness of the home, whether very leaky, average, or very tight
- Window area particularly on the south and west sides of the building
- Window efficiency
- Amount of shade
- Family size and lifestyle-larger families release more heat energy into the house from body heat and activities such as showers and cooking.
Efficiency
Central air conditioners are rated according to their Seasonal Energy Efficiency Ratio, or SEER. Units are labeled with an Energy Guide label that lists the SEER and compares it to the ratings for other similar models. The higher the SEER rating, the higher the efficiency and the lower the number of kilowatts per ton installed. Units with a SEER of 10 normally are sized with 1.2 kilowatts per ton. Units with a SEER of 12 normally are sized with 1 kilowatt per ton.
Electric service rates
Central air-conditioning systems can be operated on Otter Tail Power Company's general service rate.
Estimate your operating costs
Hours of operation x tons of cooling capacity installed x kilowatts per ton (this is the SEER rating factor) x Cost per kilowatt-hour = Operating cost for a cooling season.
For example, a 2 ton air conditioner with a SEER of 10 operated for 700 hours over the summer in the in the Fergus Falls area would calculate out to the following cost of operation:
700 hours of operation X 2 tons X 1.2 kilowatts (kilowatt factor based on the SEER rating of 10) x $.053 (cost per kilowatt-hour) = $89.04 to cool during an average season.
