Tutorial Ventilation 101

[BongCalledYoda]

Quick Question... Would the fact that when I turn my exhaust to a higher speed the temp goes up be due to too much passive intake? The fan should be moving way more air than I would need but I cant shut the door of my cab without a crazy heat build up... Glad I could find some fan gurus to hopefully get me on the right path. Thanks in advance.

 

[lysol]

Is there air flow over the heat source ( lights )? If there is then increasing the flow should cool them. If not then increasing the flow would just suck the air further away from the lights , see my prev. diagram. Id suggest putting a fan inside the box or placing the intake and exhaust on opposite ends of the heat source to make sure the air flows around the light itself

 

[BongCalledYoda]

I have exhaust at the top right corner, right next to the light. Passive intake at the foot of the left side. Plus a little fan blowing from the floor onto the light. I should have plenty of air movement around the light... I just don't know what else to do and refuse to spend more money if it won't be fixed... Thanks for the input

 

[lysol]

What I am saying is place your hand over the light and make sure there is air flow. If your intake temps aren't at least 6 degrees cooler then then the light its not going to do anything either.

 

[BongCalledYoda]

I understand that. The air is flowing around the light and the intake air is much cooler than the light, that is why I am confused.... Thanks again

 

[Dank Sinatra]

well than whats the temperature of a 1000 watt bulb?

 

[BongCalledYoda]

I have no idea.. I am using a 150 watt and the intake air is ac controlled 72

 

[JohnnyToke]

Quick Question... Would the fact that when I turn my exhaust to a higher speed the temp goes up be due to too much passive intake? The fan should be moving way more air than I would need but I cant shut the door of my cab without a crazy heat build up... Glad I could find some fan gurus to hopefully get me on the right path. Thanks in advance.

what kind of exhaust fan do yo have (make, model)?

is it sealed tight to your cab where it only pulls air from within the cab when the doors are shut?

how big are your intakes?

once these are answered, I think we can help you out better.

 

[BongCalledYoda]

Thanks JonnyToke. Right now I am using a Stanley blower( if this is my weak link I have no problem changing that) It is sealed tight to the cab and only pulls air from inside when the door is closed. I have 4 2" passive intakes but 2 are taped shut since they didnt appear to be helping. With the door open the temp stays in the high 70's but if I shut the door it climbs to high 80's or even worse low 90's. I have no problem with changing the set up, just want to be sure my problem will be fixed after the change... I appreciate the input but my plants thank you more...

 

[BongCalledYoda]

Forgot to mention the exhaust is 5" with a 5" to 4" decrease. thanks again

 

[JohnnyToke]

you need at least twice as much passive intake opening for air to be pulled in verses where it is exhausted.

if your exhaust is a 4" circle opening, you would need at least eight 2" round intakes to double it.

area of a 4" circle is 12.566 inches. you need double this amount of area minimum on your passive intake openings for proper airflow.

area of a 2" circle is 3.142 inches. it takes at least 8 of these to double the area of your 4" exhaust. thats assuming the exhaust opening is round. if its a 4" square opening, the area goes to 16 inches which would mean you would need at least 32 inches (11 x 2" round intakes) of area openings for your intake.

unplug your 2 holes so yo have all 4 open. then drill 4 more. if it were my cab, id drill another 6-8.

let us know how it works out for your temps.

hope this helps.

JT

 

[BongCalledYoda]

Thanks JT. I had already unplugged the holes and with a few minor tweaks I got the temp in the low 80's with the cab door shut, like so-

temp stays steady so I think it might be cleared up.
and open with the exhaust exposed-

Thanks for the input guys and I should not have much longer on the girls so I'll let you know how that goes.

 

[jaded1]

superb thread,took a bit of time for it all to sink in but think have it worked out now.thank you,top drawer info!!

 

[dixbutler]

Just planted 4 more skunk. What are you indoor guys using to move air. I've got these dayton blowers, that I thought would move plenty of air, but I still seem to be running hot in the box even with T12s. I'm not burning or wilting my plants now, but when I open her up, I can feel the heat come out(I placed my thermometer up high in the old box and my light fried my thermometer it read 40 at about 70 degree room temp). I got a 4 inch pipe going to the blower, and about 60sqin of passive intake. The blower is 3030 RPM. It blows into a scrubber.

I'm thinking I need more intake, and maybe more holes in my scrubber, but if I don't have enough blower, I'll start on another tact.

Thanks

 

[FreezerBoy]

I have 4 2" passive intakes but 2 are taped shut since they didnt appear to be helping.

You're seriously choking the cab to death. You don't want four 2" holes (12.56 sq inch), you want two 4" holes (25.12 sq inch) maybe more. Whatever you used to cut the exhaust port, use it again and cut 2 holes for intake.

 

[hoosierdaddy]

I'm having a heat problem and suspect airflow issues...so I tape up two of my intake holes.
(scratching head)

 

[dixbutler]

I got a new box. Downstairs: 60"X33"X48" perpetual grow. Upstairs: 42"X33"X33" 5 plant scrog and 2 single scrogs. 16"X17"X33" mom/pop room. 16"X16"X16" utility room. Atic: 16"X16"X17" ventilation room.
I'm going to put the 400 watt HPS in the downstairs part with a few CFLs for the perpetual grow, and put the T12s upstairs in a scrog with 2 bucket scrogs. I'm going to remote ballast the T12s as well as the HPS.

I'm going to suck air into the downstairs through vents to the upstairs. Then into a mom/pop room. and finally to scruber.

I'm going to get a 4" can fan or the like. Do you think that's enough? I was going to put my dayton blower on the HPS, but I'm not sure what to do with it. Should I let it go in the one of the upstairs apartments, or vent it and scrub it by itself?

I had in mind that the 4" can would suck through a scruber in the mom and pop room, which would suck through two 4" light trapped holes from the upstairs compartment, which would suck through 4 4" vents(one of which would be the dayton blower) from the downstairs apartment which would suck intake through a 33"X31" light proofed vent.

do you think it will work?

 

[Black Sheep]

hey all! im researching the ventilation now and im not sure if my idea will work or not. so i thought i would describe my idea and see what everyone thinks. the dimensions of my box are 4'Wx4'Tx2'D it will consist of a 2'x2'x4' flower room, 2'Wx2.5Tx1'D mother room, 2'Wx1.5'Tx1'D clone room, 2'Wx1.5'Tx.75'D drying room. now heres where it gets a lil complicated. the air will enter the flower room and drying room simultaneously and will merge together in a hidden wall behind the mom n clone room. it will the flow thru the bottom of the mom room from the back and up thru the mom ceiling/ clone floor and out the top back wall into the scrubber room which will house a home made scrubber and 180cfm squirrel cage blower with a fan speed adjuster. my questions are: #1 the 180 cfm fan going to be sufficient enough to keep the entire cab cool without fan cooling the lights? #2 with the air leaveing the flower room at the top,would the air now be too hot for the flower/clone rooms? #3 the cab is going to be made of 1/2" mdf and the ventilation in the hidden room will be made of the mdf so it will have square edges(and it will be sealed). with all the turns going past square edges will this create noise? #4 and will it stress the fan at all? it may sound confuseing and i wish i was better with the google sketch up to show exactly what im trying to say so if there are any questions about my questions or cab design feel free 2 ask. and if im doing something wrong that you see then dont hesitate to tell me. i dont mind criticism at all it will only make my cab better and me a better builder.

 

[BigForest]

technicaLLLLLLLLLLLLLLLLLLLLL

 

[phr3d0m2gr0]

Thank you red for a great post. Gave me some new ideas on redoing the ventilation in my cabinet. Blaze one for you!