Our bids vary. Some say to remove the old elbow, have them install a new one & reseal the roof around it. The old unit and elbow are 20 years old this year and the elbow is well foamed into the flat roof. Others say removing it will cause further problems, potential leaks and the cost of having a company refoam/reseal the roof are astranomical. Some companies included roof repair in their bid as they employ roofing people or have roofing and plumbing branches, along with AC. Will a transition mean less efficiency? Some say yes because our ducts are already too small for the ton unit and a larger return already has to be installed because the house was built with too small a return to begin with and then we also added an addition. We're in the South Central Arizona and looking at a 4 ton, 14 seer package. Our house really needs a 5 ton unit but the ducting can't handle it and we don't want our whole house torn apart. The previous 4 ton was sufficient and we put a lot of money into the house already. When we furnish the addition with skylight covers, it should reduce the heat in that 400 sq.ft. So, what are other professional thoughts? Transition or elbow removal? My thought is that there isn't any reason why the roof cannot be resealed properly and I tend to go with a new elbow. However, one company said that a new elbow would not be as efficient because the elbow is very well insulated, more than what a new elbow would be. Another company said the insulation would have deteriorated over time. Dilemma.