So why would anyone consider replacing one coil and not the other? The answer isn't as simple as you think, and the 13 SEER transition has brought the ongoing mismatched coil debate to a head. At the heart of the debate is what should contractors do if they replace an existing, lower-efficiency condensing unit with a 13 SEER unit. Should the existing indoor coil automatically be replaced as well? Or can they simply install a thermal expansion valve (TXV) on the existing coil to increase its efficiency?
Manufacturers differ in their responses to this question, so it's no surprise that contractors have different approaches as well.