It's a killer. I have tied myself in knots over the venting issue. I'm leaning towards venting into an adjacent room using a carbon scrubber together with an ozonator or two. Widening my 2" PVC pipe to 4" will be all kinds of hassle. It can be done but it would require joining with the vacuum exhaust. No windows in my grow room. There are windows in the adjacent room and I would leave them open to get some fresh air but the plants will have to do with the relatively stale air in the basement. Of course, I plan to include a few intake vents but these will be drawing air from the basement. I can't say what the relative humidity is precisely. I would imagine it is on the higher side depending on the time of year without a great deal of fluctuation from day to day. I do not want to get into AC issues if it can be avoided. Thoughts on this issue appreciated.

Less than ideal I know but these are the conditions that I'm working with. Vent and other construction issues are not a problem. I can build whatever I need.

Thanks for the input.