Gastanker, I was actually looking for this very info. as I have a similar set up to Horchen. So, let me ask a follow up question for my new set-up, if I may...
passive intake low>150 c.ft closet (600w) w/TD150 inline (293 cfm pulling heat off light and room)>6">4" reducer>through wall>damper>4" duct runs behind washer >behind dryer >damper>y connector (with add'l backdraft damper in the duct so dryer heat doesn't back up>exit.
Does this sound okay to you in principle?... Got a caution regarding the reducer from someone, however, the person never came back and clarified what the problem with that reducer might be. I perfected the exhaust while working in a tent in the closet for two grows. Which is why there is a total of 3 dampers... learned a couple of things the hard way! So, I was wondering what might be the biggest problem with using the reducer... possible bogging down the exhaust fan? Fire hazard?
I need to do some more tweaking prior to flowering... sorry ladies!.... I honestly don't think the S&P TD150 can do an efficient job with a carbon filter without making my temps go up too much, certainly not something rated for 300cfm. I finally achieved a steady 79f, but hope to take it a few lower for a "buffer zone". I'm trying to figure this out without cutting anymore holes. Intake is working fairly well with slight neg. pressure still.
I am using an air-cooled hood and I have read it isn't good to vent room air over your bulbs with a carbon filter in front. Starting to think I may have to get a different fan. I have no first-hand knowledge, but I also read that just taking the light out of the equation doesn't reduce the heat a whole lot... Ambient temp 72f... so was feeling pleased with myself to get 79.
I hope it is okay to ask this here, or should a make another thread? Appreciate any suggestions. Thanks... and thanks to the op for asking for this type of info right when I needed it!