I am setting up some HVAC Zones in my home. I bought the motorized dampers and the bypass dampers. I did not take a scientific approach and just guessed at the size of the ducts/dampers based on what was there. That is if the "zone" had one sized, I added a "feeder" duct 2-3 inches bigger. Now I am worried the ducts are too big? Is there such a thing as too big ducts? The biggest is a 14 inch that will feed 2 existing 11 inch ducts. Any help before I get started would be appreciated.

Any problems with the ducts being too big will be compensated by a slightly different setting on the damper. It is not like dust collection system where if the air velocity is too low, the dust falls out and eventually the supports collapse from the weight of the dust.

I am not an AC man but my guess is the larger size of ducts will not cause you problems. My AC man tells me the larger and longer the duct is - the more quiet operation it will produce.

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