I currently have an over-sized furnace for my home square footage. I'm happy with the duct's performance, they are quiet.
The furnace is 27 yo and I'd like to replace it with a heat pump and air handler. To keep the project cost down, I would prefer to keep my existing ducts.
I would step down to a 2.5 ton system from the 4 ton furnace - what would I expect to happen if I keep the ducts?