Hi everyone. I was hoping I could receive some help to control my temps in my cab: 39Hx13Wx28L Cab 5 x 27w CFL S&P TD100 (4in 100cfm) 4x12 Phat Filter (Rated up to 200cfm) 8inx10in passive intake with homemade darkroom louver for light proofing Right now with the 5 27w CFLs, the cab is running at about 13 degrees hotter than room temps. I'll be installing an AC in the room shortly, but still calculate that I need to bring that gap in temps closer. I'm curious what everyone's thoughts are on my current intake. I heard darkroom louvers are extremely resistant to airlfow, but even if it was decreasing airflow by 60%, it still comes out to double the exhaust (4in duct from TD100). Currently I have the filter mounted vertically, but near the top of the cab, with about a foot of ducting to the fan, and then about 2 feet of ducting out of the cab. It's really the only way it can all fit. Does the fan need to be closer to the exhuast/ less ducting? My plan was to start with CFLs, and then switch over to my 150w HPS, but temps would be even worse. Any and all help would be greatly appreciated. Thanks!
any bends in the ducting will reduce air flow by a %. Accordion style plastic ducting also restricts airflow. If you can afford to, use straightwalled ducting for hvac rather then the flexy dryer ducting. If the door sucks itself shut pretty good then you could stand to increase the intakes...that's a sign that you have excess negative pressure in the cab which is a result of restricted airflow. How are the intake louvers designed? By far the best design I've seen is the 'scrublouver' style light trap...it's an easy diy, is very slimline and restricts the least amount of air. also when measuring temps, place the thermostat at canopy level but in the shade. Direct light can cause false readings. If you can afford it buy a infrared laser temp gun..they run about $20-30 online. You can use one of those to directly check the temps of the plants themselves which is far more accurate.
Good advice, thank you. There are 270 degrees worth of bends in the duct from the fan to Exhaust so maybe I can cut that down if there's space. Also, it is the accordion style ducting, but I think i may have to stay with it due to the flexibility of use. The door is a pretty heavy and on European hinges instead of loose hinges, so not sure how accurate my guess is, but it did not seem to want to pull in. The darkroom louver is DIY with I believe quarter inch 90 degree corner molding from home Depot. The spacers were made with the same material so spacing is the same width as the pieces themselves. In layman's terms, I saw that as 50% airflow which is why I made the intake much larger than just 2 4in intakes. Also, my temp gauge is near the top of the box because I wanted to see the worst case scenario and adjust from there. But now That you say it, it makes sense to put it at canopy level as that is where temps truly matter. Right now it's reading 99 degrees and 35% humidity...
yeh those bends will reduce alot of flow..especially with the accordion style stuff. There's another accordion style I've used that's made of thin metal...can be difficult to find though and it gets some minor air leaks. If you can also make the bends so they're not real sharp, that will help too. Ya know..like make em more rounded. Like a 'U' instead of a 'V' I think I use the same diy louvers. If you can take the entire louver(s) out...and see if that decreases temps (just as a test) ..if temps do decrease you could stand to have a bigger intake. the top of my grow box above the lights at the filter is about 95degrees.