Based on information I received from this board I asked my salesman why he chose the Carrier FX4CNF036 air handler with the 25hpa536 carrier condensor instead of the FV4B variable speed air handler?
He said the FX air handler is an EEM controlled unit and the FV air handler is an ECM controlled unit. The "Latent Heat" removal (humidity) is identical with both air handlers. The only difference is that (with the FV) you can take advantage of slightly better humidity control during operation if you have a Special control unit (Thermisdstat).
He said he quoted the FX because the replacement cost of the Blower Motor for the FV (after warranty is up) is much more than the FX. He said when he looks at long term "cost of ownership" he would recommend the FX. However he will go either way I want.
Which would you choose for a southwest florida home built in 1981 with original duct work?