I was wondering if anyone could help me out with a duct problem and a heat problem. Let me start off by saying I'm originally from NJ with 3 family members in the HVAC field. I worked for one of the family members and understand a little more then Joe the home owner. Probably more of the sheet metal work and installation of trunk. I now live in FL and apparently the atmosphere is different here. I have a heat issue. I purchased my home from a very old lady and very very much over weight. The reason I gave that background is because I think it added to my issue. I have a 34 yr old home with tiled roof in great shape BUT my windows are aluminum single pane and my insulation is equivalent to an r8. The energy company said the standard is about a 30. So I know I need to up date. I will after I can get this duct and heat problem fixed.....Now I have a 3 ton Heil air handler, no heat pump. It's about 6 years old but the ductboard is 34 years old and is brittle and leaked air in the attic pretty bad. I believe that in the winter, the overweight lady wasn't affected by the cold like my 185ld frame and 50 and 75lb children. So the heat wasn't much of a problem to her. I was wondering what size plenum and supply run I should use. I have about 57' of run with 2 elbow and about 10 supply vents. My home is 1606 sf. Being that I'm here in FL, is 3 ton ok for 1606 sf. The heat coming out closest vent to the a/h is coming out at about 91 degrees. What should the temp. be coming from the vent of an electric a/h? Do you think my heat strips are bad? Will the improper sizing of the supply ( 12 off the plenum with elbow for 25, 10 for with elbow for 20 and 8 for 12 [all in flex]) vent effect the amount of heat the heat strips are giving. Id greatly appreciate guidance. I can run supply and fabricate a plenum and takeoffs. Also, my return is 10x14 (inside diameter) ductboard trunk. Main original supply was the same. I may have worked for the old a/h but didnt work for the newer one. Sorry about the babble, just trying to give as much info from the top of my head.