Currently, we have the following split system using the old freon - Heat Pump : Lennox HP26-042-7P (published SEER 14.65) and Air Handler Lennox CB31MV-51-1P. We live in Southeast Texas, where humidity removal is important, thus the 3.5 tn HP and 4 tn AH. These units were installed in 2000. The heat pump was damaged when the electrical service had problems (transformer) over a 12 hr period. The homeowners insurance is covering the HP replacement. They are saying that our existing air handler can be retrofitted with a new valve, the lines flushed, and a new Lennox XP14-042 installed using R410A. Because of the SEER rating of above 14, the insurance will match that number. The dry charge HP units that are available are all 13 SEER. From what I've been told, R410a operates at higher pressures than the old freon. My question - can the old air handler (designed for freon) handle the increased pressures required by the R410A? Will this flush kit clear all the mineral oil out of the AH coils and linesets? The companies that have given us bids (and have seen the installation) say that both units of the system need to be replaced. Any advice would be appreciated.