"Here are some general rules of thumb when you are ready to replace your existing equipment: # Choose a manufacturer that has a good reputation for quality and durability. # Choose a model that with a high efficiency rating to bring you better comfort and lower your seasonal energy bill. # Choose the correct equipment size and system for your home. # Don’t just buy a unit just because it is on sale and seems like a great deal at the time; do some research on the product or ask the installation representative for more product information. # Finally, choose a reliable company with excellent customer satisfaction and a track record of service after the sale. Talk to your friends and neighbors."