I've been having problems with my Waterfurance unit from day one.  My KW usage is the same in heating and cooling mode.  My installor installed a EZ072, 3 thru 6 split unit. and a five ton air handler with a ECM2 1 hp motor.  In cooling mode the unit runs all the time and doesn't keep up. This has been going on for over a year.  It's been costing me double what Waterfurance advertises.  I think my problem is my ductwork.  He installed 14 inch round for the main supplies?  I think it should be 20 inch for 2400CFM's.  He has the high speed set to 1850cfm's on my zoning panel.  He telling me that the ECM2 motor will push that much air threw the 14'' round?  I think he used 14 inch to make the most profit.  I think for the unit to work right. I will need new duct and larger returns?

Can anybody tell me if a ECM2 motor can push 1850cfm's threw a 14'' round pipe?

Have you tried talking with a technical rep from the manufacturer?

you can download a ductsizer here