When changing the outdoor unit, should the indoor unit also be changed?

The answer is, probably so. Here's why.

Matched System Design: All air conditioner and heat pump outdoor units are specificallyintended to work with a matched indoor unit for optimal efficiency and performance. The result of this matched equipment is a harmonized, top-performance team that ensures dependability and efficiency. Air conditioner and heat pump outdoor units may ”run” with indoor units other than those for which they have been specificallyfabricated; however, the result would be a definite compromise in system performance.

Design Advances: Over time, indoor blower coil units have undergone a number of design advances — especially in the areas of air handling performance, filtering efficiency and operating sound levels. A new outdoor unit will also incorporate the latest design advances.

Higher Cooling And Heating Efficiency: The cooling and/or heating efficiency ratings that are presented for an air conditioner or heat pump are based on their performance as matched systems. While changing only the outdoor unit may consequence in improved efficiency when looking at your new system, efficiency will be lacking from what it was designed to be, and your savings will be less than with a matched system.

Equipment Age: If an air conditioner or heat pump is 10 years old or more and is ready for replacement, the indoor unit is likely just as old and has been subjected to the same amount of wear and tear. Substituting both units means you won't have to replacethe indoor unit in a short time period… you'll have more years of efficient service from both units.

New Warranty: A new system also delivers you a new product warranty. Substituting the indoor unit together with the outdoor unit results in peace of mind, knowing that the new warranty covers the entire system for the same period of time.

A Bargain: At first glance, substituting only the outdoor air conditioner or heat pump may appear to be a savings. But, when you consider the lower cooling and heating efficiencies, decreased reliability and high cost of ownership that results, it's not such a bargain. Replacing an entire system may cost more, but you get much more efficiency, reliability and comfort for years into the future.