I have a 20 year old Goettel 4 ton packaged unit I am replacing. I am thinking of going with the Lennox 15CHPXA-48-230 which is another 4 ton packaged unit. One of the reason for this device is the MERV 16 pleated filter that removes over 95% of particles down to 0.3 microns. Wife and kids have asthma and allergies I am hoping the filter helps with both. The other packaged units I looked at do not have the whole house type filter.
The contractor will not install the 4 ton unit with out replacing the over/under and riser duct work with a side by side setup. He says a 4 ton unit is to big for the 90 degree elbow and will create to much back pressure causing premature compressor failure. So far I do not have a problem until he said the rigid riser would be replaced with flex duct. This is only a 3 to 4 foot run straight up to the roof unit. Is this something to be concered about or really no problem since the run is so short?
Thanks for all of the great info here.