Sounds like you already know the answer: oversized ducts are not a bad thing. Only a small hit for cost, and possibly some routing issues if you're running through a floor system, etc.Originally posted by lginla
Most of the replies here imply that a duct that is "too big" is bad...
Then how do you design a ductwork for a two-stage system whose air flow varies by 40% or so? If you size it for the higher stage, won't the system then be "oversized" for the low stage, which most respondents say is bad?
Having said that, if the diffusers are too large, air throw may be less than optimal. However, this becomes a non-issue in a properly insulated house.
Finally, balancing, which is indeed important, can be accomplished with an oversized duct system in the same way as with a 'properly' sized duct system (e.g., by selecting correct relationships between various trunks, run-outs and difussers, and if necessary, using balancing dampers). See my earlier response, above.