Grow cabinet design help

[extremophile420]

I am designing a 2x4 wooden grow cabinet, it will be powered by two HLG QB96, and i want to be sure to design it right and create the best grow environment. I am having a hard time deciding on ventilation holes placement, i have two designs in mind and i want to know which is the most effective design, taking into consideration maximum stealth. The cabinet will be placed in a room with a window in front of it, but the back of the cabinet will be a few inches away from a wall. This will bring my ventilation questions.

Design 1

In this design two 4 inch intake holes will be placed on the bottom of the cabinet, and a 4 inch exhaust hole is placesdon the top roof of the cabinet, i am leaning towards this design the most, since its the stealthiest, with some decorations on top of the cabinet and nothing will show.

Design 2

In this design the intake holes are places on the bottom back of the cabinet, and the exhaust of the top back. I see this design is the most common, but i am concerned for two reasons, first is that the back of the cabinet is a few inches away from a wall, and i am not sure if that would harm im passive air intake. And the second reason is that i am afraid that the intake holes will suck back the exhaust air because i will be exhausting in the same direction. (impossible for me to exhaust anywhere but in the same room)

I want to put the carbon filter and fam horizontally in the middle so i can gain more headroom for the lights, thats why the exhaust holes are in the middle of the cabinet.

If there is better designs than the ones i came up with please share with me. I want to grow the best weed.

 

[TurboBucket]

Don't do number 2 unless you make a couple deflectors or some flex duct around the intake holes so they only pull air from around the corners on the backside, not from the exhaust air in the middle.

Your better off having the intake and exhaust on opposing sides so the air is pulled through the entire space. If they are on the same wall it won't mix through the space as well. Air is lazy it follows the path of least resistance, negative pressure is the lowest resistance wherever you're pulling air from is where it will want to flow to. The longest path from intake to exhaust would give you the most effective use of the fan.
If you could go from bottom on the left side to the top on the right side it would be better. You would also be able to place the cabinet flush to the wall rather than needing to leave an air gap. It also moves ports from the front side line of sight to the less visible ends of the cabinet

Depending on your floor space you may be able to hide the fan/filter combo in a slotted/ported box next to it. All the smelly air would still be under negative pressure so it won't leak stink out.

What are you doing to prevent light shining out of the holes?

 

[extremophile420]

Don't do number 2 unless you make a couple deflectors or some flex duct around the intake holes so they only pull air from around the corners on the backside, not from the exhaust air in the middle.

Your better off having the intake and exhaust on opposing sides so the air is pulled through the entire space. If they are on the same wall it won't mix through the space as well. Air is lazy it follows the path of least resistance, negative pressure is the lowest resistance wherever you're pulling air from is where it will want to flow to. The longest path from intake to exhaust would give you the most effective use of the fan.
If you could go from bottom on the left side to the top on the right side it would be better. You would also be able to place the cabinet flush to the wall rather than needing to leave an air gap. It also moves ports from the front side line of sight to the less visible ends of the cabinet

Depending on your floor space you may be able to hide the fan/filter combo in a slotted/ported box next to it. All the smelly air would still be under negative pressure so it won't leak stink out.

What are you doing to prevent light shining out of the holes?

I cant place the intake holes on the sides of the cabinet since i want extreme stealth. I live in a country where i have to take these precautions.
I will be using 4 inch darkroom louvers on the intake holes, and for the exhaust i think the ducting will take care of light leaks. My exhaust duct will be directed vertically towards the ceiling, and air is pulled from the floor, if i do design 1,Do you think this is a good idea? I want to do it right from the first time since i cannot afford changes later down the road.

 

[extremophile420]

Don't do number 2 unless you make a couple deflectors or some flex duct around the intake holes so they only pull air from around the corners on the backside, not from the exhaust air in the middle.

Your better off having the intake and exhaust on opposing sides so the air is pulled through the entire space. If they are on the same wall it won't mix through the space as well. Air is lazy it follows the path of least resistance, negative pressure is the lowest resistance wherever you're pulling air from is where it will want to flow to. The longest path from intake to exhaust would give you the most effective use of the fan.
If you could go from bottom on the left side to the top on the right side it would be better. You would also be able to place the cabinet flush to the wall rather than needing to leave an air gap. It also moves ports from the front side line of sight to the less visible ends of the cabinet

Depending on your floor space you may be able to hide the fan/filter combo in a slotted/ported box next to it. All the smelly air would still be under negative pressure so it won't leak stink out.

What are you doing to prevent light shining out of the holes?

And next to the cabinet i have exatcly 4 feet wide space that i want to use for another cabinet sometime down the road to run a perpetual grow, both will be placed back to the wall. Thats the only place i can use to grow i have no other placing options.

 

[TurboBucket]

So your going to have the cabinet pulled 4 inches off the wall with a pipe blowing air vertically? And that's supposed to be stealthy? I guess if you placed some electronics in a box on top of it you could say it was for ventilating those.

If you can't have them on the sides you can't have them on the front either right? So your only option for your criteria is design #2.

 

[extremophile420]

So your going to have the cabinet pulled 4 inches off the wall with a pipe blowing air vertically? And that's supposed to be stealthy? I guess if you placed some electronics in a box on top of it you could say it was for ventilating those.

If you can't have them on the sides you can't have them on the front either right? So your only option for your criteria is design #2.

The intake holes will be place on the floor of the cabinet, underneath it, and the cabinet will be lifted a few inches off the floor, with 4 inch darkroom louvers you cant really see anything unless you bend down and look underneath it.
And for the exhaust it will be on middle ceiling of the cabinet, with furniture on top of the cabinet to hide the duct.
And electricity hole will be also on the floor, that way i can press the cabinet to the wall and it will look completely normal. I think you understood the intake holes places wrong, its on the floor not tue front.
Do you think this is a good ventilation setup?

 

[TurboBucket]

I think masking the airflow is more important to keeping it hidden than just hiding the louvers.

Yes that makes more sense, I was just about to suggest putting them on legs and pushing the exhaust air down the back and under the bottom out the front, very hard to see air moving on the floor compared to eye level, and it'll help keep your toes warm. Haha.

 

[extremophile420]

I think masking the airflow is more important to keeping it hidden than just hiding the louvers.

Yes that makes more sense, I was just about to suggest putting them on legs and pushing the exhaust air down the back and under the bottom out the front, very hard to see air moving on the floor compared to eye level, and it'll help keep your toes warm. Haha.

The cabinet will be lifted 4 inches off the floor to let air pass underneath it. Amd with the darkroom louvers placed on the inside, underneath the cabinet will be relatively clean unless you search for the holes lol. Do you think that would offer good air flow? Wood mistakes are costly,and i am neat by nature i want a clean and neat cabinet. Drilling more holes down the future and modifying will make me literally replace the whole cabinet

 

[TurboBucket]

Yup sounds good.

 

[extremophile420]

Yup sounds good.

Do you think a carbon filter and fan woukd feet in a 2 feet space? I wanna place them in a in the middle of the cabinet so the qb 96 can be hung right next to them to gain more headroom.

 

[425jesse]

Do you think a carbon filter and fan woukd feet in a 2 feet space? I wanna place them in a in the middle of the cabinet so the qb 96 can be hung right next to them to gain more headroom.

Take notes on the sizes from the manufacturer, and map out the interior of the box. No room for error, so engineer it the first time. Good luck!

 

[extremophile420]

Take notes on the sizes from the manufacturer, and map out the interior of the box. No room for error, so engineer it the first time. Good luck!

I just did, i have a limited range of choices but i think thats ok. I was thinking of placing the fan and carbon filter horizontally along the width of the cabinet, but i will lose abkut 1 feet of headroom.

 

[cr8grow]

I built a 3x3x6.5 cabinet with passive hepa filtered intake through light box, 4” carbon filter and fan...now close to finishing (hopefully) my first grow. I bring air from the back at the bottom at pot rim height and pull it through the filter top front, straight out the back near the top. I have two small fans circulating air...all runs 24/7. One caution is fan noise...my crate is in the unfinished section of my basement. I can faintly hear it from some rooms upstairs...certainly when in the unfinished basement...OK for my situation. Additional Pics upfront in my grow journal show design, build and final cabinet...

may give you some ideas.

 

[extremophile420]

I built a 3x3x6.5 cabinet with passive hepa filtered intake through light box, 4” carbon filter and fan...now close to finishing (hopefully) my first grow. I bring air from the back at the bottom at pot rim height and pull it through the filter top front, straight out the back near the top. I have two small fans circulating air...all runs 24/7. One caution is fan noise...my crate is in the unfinished section of my basement. I can faintly hear it from some rooms upstairs...certainly when in the unfinished basement...OK for my situation. Additional Pics upfront in my grow journal show design, build and final cabinet...

may give you some ideas.

Looks clean man. I was thinking about adding two 4 inch holes at the bottom, with black 90 degree pvc underneath the cab then coming into the cab, but im still debating about its stealth.

I am afraid that if i put the intake on the back of the cabinet i will restrict air flow since i have little space available and the cabinet will be only 1 or 2 inches away from a wall.

 

[cr8grow]

Passive intakes underneath is a great idea...could be easy to block light with some strategic wood pieces and flat back paint...ambient light above wont reflect well underneath. Just make sure your passive opening size or sizes are equal to or exceed the diameter of your exhaust fan. I made passive opening a bit bigger to offset the decreased flow due to the hepa filter and the light box interior angles.

 

[425jesse]

Also, if it hasn’t been mentioned, inkbird makes awesome temp controllers, and they are cheap compared to almost all others.

 

[cr8grow]

Correction...and the way I cut my passive intake...needs to be at least 2x...

 

[extremophile420]

Correction...and the way I cut my passive intake...needs to be at least 2x...

How do you deal with light leaks? Im planning everything before i start building the cabinet.
I will cut two 6 inch holes on the back of the cabinet, since i realized that intakes on the floor take too much floor space.

 

[cr8grow]

For the passive intake I built a light box with the same size opening...mated them up at the back and then sealed the interior around where they connect with heavy duty black tape. Inside every seam is caulked and my door opening has thick weatherstripping all around. I Have a dryer type vent at the top back. No light leaks. Couple more pics of the light box.

 

[732002]

How stealthy do you need to be? I found exhaust fan noise to be a issue.

I don't think location of intake and exhaust is critical. You will have fans inside that
will mix the air up. Go with what is most convenient.