Ensure your old unit needs to be replaced.
You may be able to service your old unit without replacing it all together. A Trane Comfort SpecialistTM can help you determine if it's time to buy a new unit. Generally, a furnace should last 12 to 18 years with proper maintenance, though some units can last longer. An older unit, however, may run inefficiently and require lots of maintenance, meaning it may be cheaper in the long run to update an older furnace with a newer, more efficient model.
Consider size and efficiency.
You'll want to avoid purchasing an oversized unit. If the unit is too big, it can cause uneven temperature problems. Your dealer will be able to measure and inspect your home and recommend the best size. Also think about energy efficiency. Look at the seasonal energy efficiency ratio (SEER) to help make your decision. While 13 SEER is the minimum, anything above 16 is considered high efficiency.
Proper installation is key
A well-trained technician will ensure that your unit is installed properly and that there are no duct leaks when the new equipment is connected to your existing ductwork. Choosing a dealer with the proper training, equipment and knowledge will help ensure your unit is installed correctly.