Why not?....Dont you want to draw exactly the proper amount of air from each room based on cfm per room? You cant do that if you grossly oversize your return.Return air duct sizing is still based on TEL, I think your creating more air stratification with an improperly sized return air duct.I think this question would be more of a problem with Commercial work more than residential due to the similar sizes of most residential homes..Commercial work we are dealing with a 1 1/2 ton to 60 ton roof top unit so sizing is more critical and more to go wrong.You can almost be a rookie and a residential system will fairly work fine.Originally posted by seatonheating
Here's an off the wall question guys. And I do believe there was a thread on this before. But, isn't it impossible to have too large of a return, theoretically? I mean, if this guy is borderline on his return he should by all means upsize it, can't hurt anything. At least that's the way I see it. For every 100 instances of problems due to return I would think 99 of them are due to it being too small.