Gregor Eisenhorn
Well-Known Member
Hi everyone!
I have a problem with ventilation and I was wondering if anyone could give me a few pointers.
I have a small wardrobe (1.6 x 1.9 x 5.5 ft) so after some research and maths I know I have a volume of 16.7 cubic feet and to get the cfm rating I multiplie by five (five air exchanges to be on the safe side), so that comes up to the grand total of 83.5 cfm minimum yes?
**Now I have also heard that you should take into account (or just follow this rule) the wattage of your lamp, so I have a 250W HPS.
Now I am going to have to do some converting, because it's 1 Watt per 1 cubic meter an hour (or so I have heard), so that's 250m3/h = 147cfm. **
Now I had a fan thats efficiency is 280m3/h (150mm/ 6") = 164cfm, but the motor burnt... which is why I am all scared now. With a passive intake, you should have holes 3-4x the size of the exhaust, although people have been getting away with just eg. two holes (and some with just one). So that's what I did, two 6" intake holes.
Although I am not sure what caused the fan to burn out, but something was obscuring the fans movement (which is weird because the fan was working for two days and then suddenly it stopped). I was wondering if this could of been because of my shit calculations. Maybe the fan was too stressed out because of the lack of sufficient intake holes? Or maybe the fan itself was shit and somehow the fan manged to loosen? Or maybe even there was too much negative pressure (because the fans cfm ratings are enough for the cab) and the soft plywood that the fan was installed in, somehow tightened it's grip on the plastic fan? I really have no idea at this point, although I know that when I get a new fan, it won't be half sitting in the plywood wall, but I'll get some ducting and hang the fan inside the cab.
Now after a lot of rambling, the other problem I have is light leaks... the 6" intake holes are just too big for any PVC pipes. The only ones I can get my hands on are 110mm (4.3 inches) (and that solved the light problem). Now with this in mind, would it be safe to buy myself the same fan I had and just install it again even if the intake holes are de facto "smaller"? I was wondering if anyone has any experience with this kind of problem. If not, then I may be just forced to either do an active intake, by attaching a small computer fan to the PVC intake holes (the cfm ratings of the fans will be condierably smaller then the exhaust fan, which is the whole point correct?), but a lot of people shun this type of intake, which is getting me worried and thinking (terrible combination)... OR buy myself a much much smaller 120mm (4.7 inch) fan with a 88cfm rating, and then my intake holes will be more than enough. You see that's why I don't know which rule of thumb to follow: the rule of wattage or the rule of multiplying grow box volume.
Thank you very much for your time, and forgive my lack of knowledge, but at this day I feel completely drained of ideas...
I have a problem with ventilation and I was wondering if anyone could give me a few pointers.
I have a small wardrobe (1.6 x 1.9 x 5.5 ft) so after some research and maths I know I have a volume of 16.7 cubic feet and to get the cfm rating I multiplie by five (five air exchanges to be on the safe side), so that comes up to the grand total of 83.5 cfm minimum yes?
**Now I have also heard that you should take into account (or just follow this rule) the wattage of your lamp, so I have a 250W HPS.
Now I am going to have to do some converting, because it's 1 Watt per 1 cubic meter an hour (or so I have heard), so that's 250m3/h = 147cfm. **
Now I had a fan thats efficiency is 280m3/h (150mm/ 6") = 164cfm, but the motor burnt... which is why I am all scared now. With a passive intake, you should have holes 3-4x the size of the exhaust, although people have been getting away with just eg. two holes (and some with just one). So that's what I did, two 6" intake holes.
Although I am not sure what caused the fan to burn out, but something was obscuring the fans movement (which is weird because the fan was working for two days and then suddenly it stopped). I was wondering if this could of been because of my shit calculations. Maybe the fan was too stressed out because of the lack of sufficient intake holes? Or maybe the fan itself was shit and somehow the fan manged to loosen? Or maybe even there was too much negative pressure (because the fans cfm ratings are enough for the cab) and the soft plywood that the fan was installed in, somehow tightened it's grip on the plastic fan? I really have no idea at this point, although I know that when I get a new fan, it won't be half sitting in the plywood wall, but I'll get some ducting and hang the fan inside the cab.
Now after a lot of rambling, the other problem I have is light leaks... the 6" intake holes are just too big for any PVC pipes. The only ones I can get my hands on are 110mm (4.3 inches) (and that solved the light problem). Now with this in mind, would it be safe to buy myself the same fan I had and just install it again even if the intake holes are de facto "smaller"? I was wondering if anyone has any experience with this kind of problem. If not, then I may be just forced to either do an active intake, by attaching a small computer fan to the PVC intake holes (the cfm ratings of the fans will be condierably smaller then the exhaust fan, which is the whole point correct?), but a lot of people shun this type of intake, which is getting me worried and thinking (terrible combination)... OR buy myself a much much smaller 120mm (4.7 inch) fan with a 88cfm rating, and then my intake holes will be more than enough. You see that's why I don't know which rule of thumb to follow: the rule of wattage or the rule of multiplying grow box volume.
Thank you very much for your time, and forgive my lack of knowledge, but at this day I feel completely drained of ideas...
