I will need to replace my central A/C system soon (~15 years old TRANE) due to inefficiency and some deterioration in the air handler. My house was built in 1962 and all the returns (5) are in the walls between the studs. The ductwork is the metal round type with fiberglass insulation (with a black paper facing). The air handler is mounted horizontally in the rafters above the garage. I got some initial opinions about system replacements with differing advice. One contractor said the original ducts were designed for heating only and were poorly insulated. He recommended replacement to balance the load and get a higher insulation R-Value. Another said that the metal ducts were desirable because rats can't eat through it. He recommended a duct cleaning and shoring-up the insulation around the ducts. All the contractors recommended changing to a vertical air-handler setup with a "mixing box" to get more even air-flow to the vents. They also recommended changing the return to a large ceiling return (closing up some of the in-wall returns).
I have a few questions:
1. What's my best move with the ducts/returns?
2. Is there any "red flags" with the advice I'm getting?
3. I like the AMANA 16 SEER system for replacement...can I go wrong with the quality, repair history, etc.
Please give me some advice...thanks.