Choosing a Central Air Conditioner (CAC)

Central air conditioning is a popular way to enhance your home. Air conditioning keeps you cool in the summer, controls humidity and can help reduce allergies. This fact sheet provides guidelines that will help you maximize the value and benefits of central air conditioning.

Buying Tips - Get the right size

Buy high SEER

Add a thermostatic expansion valve (TXV)

The condenser is the part of a central air conditioning system that discharges heat from your house to the outdoors.

Look at moisture performance

A “supersized” central air conditioning system can sound appealing, but in reality it has major drawbacks

• Higher equipment costs
  Each additional ton* of air conditioning can cost you $300 or more.
• More wear and tear
  An oversized unit turns on and off more often than one that’s properly sized. Frequent cycling causes needless wear and tear and wastes energy.
• Poor dehumidification
  An oversized system won’t run long enough to wring moisture out of the air.
• A strained electric system
  Big systems draw lots of electricity, and a city full of air conditioners can lead to more power plants and transmission lines—and higher electricity costs.

* A ton of A/C = 12,000 btu/hr. This is equal to the cooling capacity
of melting one ton of ice per day (a cube 3 feet 3 inches on a side).

Installation and Maintenance Tips

• Electrical
• Airfow
• Refrigerant Level

This checkist details those services.

Operating Tips

Use trees for shading
Plant deciduous trees on the south side of your home to provide shading from the hot summer sun. If that’s not feasible, install window awnings.

Cool at night
Air conditioners are better at removing heat when it is cooler outside. Take advantage of this fact and do your air conditioning at night.

Use natural cooling methods
If your expecting a hot day, in the morning before the heat of the day, close the windows and blinds to keep the hot air outside and the cool air in.

Reduce appliance waste heat
Minimize the use of appliances that add heat and humidity to your home when the demand on your air conditioning system is highest. Run the dishwasher at night or early in the morning. Also consider alternative cooking methods on the hottest days, like grilling outside or using the microwave. You’ll also decrease the load on your air conditioning system by buying efficient appliances that naturally produce less waste heat. Look for the ENERGY STAR label to guide you to efficient choices.

Run your system wisely
Set a reasonable thermostat temperature. A temperature of 78 °F is usually adequate to maintain comfort, especially if you also use ceiling fans to maintain air circulation. Each degree you add to the thermostat setting cuts your cooling costs by 3 to 5 percent.

Get annual maintenance
Hire a qualified service technician to maintain your system. The technician should check indoor and outdoor coils, airflow and electrical connections. Another important thing is to change the air filter on a regular basis. Clean or replace furnace filters as recommended by your contractor, or as noted on your filter packaging. This may be as often as once a month. Dirty filters can reduce energy efficiency by 10 percent or more. You can change the air filter yourself.

www.mnpower.com/hvac
Or call Minnesota Power at 800.677.8423

energystar.gov
The ENERGY STAR® program provides information on energy efficient products that meet high efficiency standards.

ACEEE.org
The American Council for an Energy Efficient Economy publishes the “Consumer Guide to Home Energy Savings.”

comfortinstitute.org
This web site provides free consumer protection reports on buying equipment and choosing a contractor.

home.howstuffworks.com/ac.htm
Learn how air conditioning works at the How Stuff Works web site.