# attic cabinet build



## old blue (May 28, 2008)

I want to build a small 4' long x 2' deep x 4 1/2' high cabinet in my attic. I'll be supplying cool air via 4 inch ducting from the central air duct. I have a 400 watt digital hps/mh combo light with cool tube. The cool tube will be open on one end to act as a cab exhaust, and the other end will be hooked to a 550 cfm fan/scrubber combo to vent light and cab. The cab will be lined with mylar also.  

Soooo, here's my big question....What material will be best suited to use, to constuct the cab??? i was thinking something like thin drywall or maybe partical board? i don't know how thin of material i could use while still insulating it from high attic heat(beach atmosphere), while also keeping the air pump, light and fan noise to a minimum???  thanks in advance.


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## 0b1kinsmokey (May 28, 2008)

Drywall imo, paint it white and put mylar bubble wrap on the _outside_ of it.  

Mylar on the inside will screw you for energy efficiency and heat.

imo, good luck


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## old blue (May 28, 2008)

0b1kinsmokey said:
			
		

> Drywall imo, paint it white and put mylar bubble wrap on the _outside_ of it.
> 
> Mylar on the inside will screw you for energy efficiency and heat.
> 
> imo, good luck



thank you.  and i want the cabinet to look like a normal storage cabinet, just in case a repairman has to do any work on the a/c unit up there. so, the bubble wrap probably won't work.

and what does mylar on the inside do to energy eff and heat??? i thought that the plants need the reflectiveness of it to even out the lights.


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## smokybear (May 28, 2008)

I would construct the frame out of two by fours and use drywall to enclose it with. Use plywood for the bottom to make it strong. Line the inside of the box with myar to reflect as many lumens back onto your plants as possible. As for insulating it against the heat outside of the box, I guess you could use insulation and actually line the inside of your box. It's really up to you though. Just my thoughts. Keep us posted on your progress. Take care and be safe.


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## 0b1kinsmokey (May 29, 2008)

i was sayin if ur attic is already very hot during the day and ur running a 400w in a 4x2x4 youll prolly rack up alot of heat with mylar since that is what its made for  

i would say cut ur losses and just paint the drywall bright white and strap that mylar on the outside so it keeps the heat out. if u were using floros or something thats a diff story. but ur using a 400w in a 4x2x4, so youll probably be doin fine on lumes and reflection regardless, IMO

but like u said you gotta keep it looking lagitemate, so do what youn gotta do.

but i would say, if ur heat gets out of hand, try takin that mylar down and let that drywall breathe that heat in. 

just my thoughts on it


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## smokybear (May 29, 2008)

I dont see what you mean. If you put it on the inside of the box, it will still keep the outside heat out. Mylar reflects much better than flat white. It will be hot in the attic. You could open the window and place a fan in the window to get some fresh air circulating around up there. You're going to run you a/c to your box so you should be good on temps as long as you have good ventilation. Just my thoughts. Keep us posted. Take care and be safe.


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## The Hemp Goddess (May 29, 2008)

I would probably frame up with 2x4s or 2x2s, use plywood on the outside, insulate between the stud bays, and use drywall on the inside covered with 
mylar.  Mylar is made to reflect light.  Insulation only does so much, it slows down the heating up or cooling down process, but it will not prevent a build up of heat no matter how good it is or how much you use.

If this was my cab, I would run T5s or a bunch of cfls for veg to help control the heat.  I would use my HID for flowering and run the light at night, instead of during the daylight hours.  I can absolutely tell you that heat is going to be a big issue and I don't believe that you have enough ventilation to handle it.  Have you checked the temps in your attic?  They probably exceed 110 degrees.    

I can't quite figure out from your description how you are hooking up your cool tube, l but it really needs to be a sealed system to be effective.  You need to pull in cool (cold) air from somewhere outside of the cab, run it over the light and have it exhaust somewhere outside the cab.  The cab itself will also need ventilation.  I use a thermo cube to turn on fans and/or coolers when the temp gets to 78 and turns off when it gets down to 70.  Attic grows can be tough because of the heat in the summer and the cold in the winter.


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## old blue (May 29, 2008)

The Hemp Goddess said:
			
		

> I would probably frame up with 2x4s or 2x2s, use plywood on the outside, insulate between the stud bays, and use drywall on the inside covered with
> mylar.  Mylar is made to reflect light.  Insulation only does so much, it slows down the heating up or cooling down process, but it will not prevent a build up of heat no matter how good it is or how much you use.
> 
> If this was my cab, I would run T5s or a bunch of cfls for veg to help control the heat.  I would use my HID for flowering and run the light at night, instead of during the daylight hours.  I can absolutely tell you that heat is going to be a big issue and I don't believe that you have enough ventilation to handle it.  Have you checked the temps in your attic?  They probably exceed 110 degrees.
> ...



The way i planned on hooking up the cool tube is, leaving one end open to pull the air from the cab thru the tube, while the other end is hooked up to a fan that is pulling the air thru the tube, and pushing it out a scrubber to outside the cab. i will have a 4in duct venting the cab towards the bottom, hooked directly off the central air main duct. so, basically the exhaust for the cool tube will act as a cab exhaust also. i've heard of this done effectively before. but never tried it.  because of all the air that'll need moved, i ordered the bigger 550 cfm fan, instead of the lil ones meant for that size cab(32cu ft).


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## 0b1kinsmokey (May 29, 2008)

i have 4 boxes 6x2x4 made of mylar and plywood, and i have to take the mylar down when i grow during the summer. having the mylar in there dramatically increases the heat if the box is sealed tight enough.

mylar is not a product specifically made for reflecting light. its made for deflecting heat. its used for security blankets, insulation of irrigation pipes and coolers. obviously it does wonders in light reflection, theres no questions there. but that is most definetely not what its made for. 

but speaking from direct experience with sealed boxes practically completely constructed of just frame and mylar bubble wrap... its very effective at keeping the heat in.

and when my room (that the boxes are in ) is 90+ during the summer, its like a never ending energy hemorage trying to keep the boxes kool. i result to taking the mylar down so its straight wood that can breath. and moving my light cycles to be on during nite, and it works perfect

tight deminsions are much harder to regulate heat in, especially with a 400w. so just thinking about that actual practical uses for mylar, and what manufactures make it for, it would seem efficient to put it on the outside to keep the heat out, rather than on the inside keeping the heat in. glossy bright white paint is plenty sufficient when u have 400w in such a small space. 

it would be overkill to risk the heat problem just for 10-20% more reflectivness. imo


the only reason i say all that is because i spent alot of money on my boxes and integrating them. just to find out when the summer hit it cost me an extra 100 bucks a month to keep them even close to optimum temps

but blue already said he cant put mylar on the outside so..  just ma thoughts


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## old blue (May 29, 2008)

ok, well i just bought 1/4 inch hardwood sheets to build the cab and 2x4s to frame it. i also bought a roll of foil lined bubble insulation wrap. i'm thinking i'll build the box and just paint the inside super white and see what kind of temps it runs with the 400 watter and fan on. and then if needed, line the inside or outside with the bubble wrap or mylar.  i wanted to keep it pretty stealth, due to it being a rented condo, just in case a maintenance man needs to check the a/c unit or something. but i can just quickly shut the system down and throw a blanket or tarp over it, if need be.  any further advice is much appreciated.


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## 0b1kinsmokey (May 30, 2008)

sounds great. just trial and error, try it both ways see what works for ya


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