Grow Room Enviromental control heat issue

[Upstate_indoor]

Ok, who has some advice on heat issues. Here are the details:

-Box size approx. 5'x4'x5'
-2x4 and plywood construction (1/4" cabinet grade for walls and 3/4" for floor and ceiling.)
-Walls and floor covered in 6mil diamond mylar.
-ceiling is just mat white paint (painted the inside with mold/mildew resistant, protective paint.)
-Passive air intake 8"x8"
-Exhaust fan: 4" 195cfm w/ adjustable speed
-Lighting: quantum board LED
-wall mounted 9" circulation fan blowing across the top of the light.

By my calculations, the box is approx. 100cf so the Exhaust fan should be more than enough even counting the total of about 4ft ducting with 3 bends (hose is ceiling mounted inside box, run inside to pull from above and near the light.)

Ok, so here is the issue. The temperature inside is reading about 85F+ (~30C) and the only way to get it down to the 70-75 range is to dim the light to unacceptable levels. The ideas I have for lowering the heat are:

1. Install a 2nd Exhaust fan (same adjustable 195cfm with dryer ducting.) To vent more air

Or

2. Increase the size of the passive intake to 16"x16" to make it 4x the size of the exhaust.

Or

3. Do both.

Before I go chopping holes in walls though, does anyone have any suggestions or see anything I'm overlooking? I know using CO2 would allow the plants to take higher temps and I know an AC unit would be the easiest answer but I would prefer to get the temps in range without one.

 

[popeyesailorman]

Just a thought... If I had a wood box, I would mount the light in the roof so the driver and heat off off the heat sink are outside of the box. Raise and lower the plants instead of the light. I have a closet with a bit more area and 80f to 83f with good air movement is fine for plants under led. 90 is NG

 

[Upstate_indoor]

Just a thought... If I had a wood box, I would mount the light in the roof so the driver and heat off off the heat sink are outside of the box. Raise and lower the plants instead of the light. I have a closet with a bit more area and 80f to 83f with good air movement is fine for plants under led. 90 is NG

That could be a good idea, ill have to see if I can make it work. The light requires 12-15" clearance above it though and I don't think I could do that without lowering the ceiling height. At ~5' floor to ceiling, im reluctant to lower it more. I may be able to make it work with a little creativity.

 

[Bill.de.Cat]

That could be a good idea, ill have to see if I can make it work. The light requires 12-15" clearance above it though and I don't think I could do that without lowering the ceiling height. At ~5' floor to ceiling, im reluctant to lower it more. I may be able to make it work with a little creativity.

Think he's meaning more on the lines of cutting hole in ceiling the same size as your light and making it a permant fixture...then using blocks or what ever to raise your pots if needed......most heat from light and driver would be outside the box to begin with...
edit: unless your saying the area it fits into is only 5 ft tall.......

 

[Upstate_indoor]

Think he's meaning more on the lines of cutting hole in ceiling the same size as your light and making it a permant fixture...then using blocks or what ever to raise your pots if needed......most heat from light and driver would be outside the box to begin with...
edit: unless your saying the area it fits into is only 5 ft tall.......

I could do that, but it would require dropping the ceiling in the box to maintain the clearance space above the light.

 

[Bill.de.Cat]

I could do that, but it would require dropping the ceiling in the box to maintain the clearance space above the light.

AAhh..ok...I was thinking you might have space above the box......only thing at that point is to increase cooler air intake....as you said another fan or / and more intake holes.....

 

[Upstate_indoor]

@Bill.de.Cat @popeyesailorman This is the light setup, so it would be tough to mount it so the heat sink it outside the box. The 2nd pic is of the space above the box.

 

[Bill.de.Cat]

@Bill.de.Cat @popeyesailorman This is the light setup, so it would be tough to mount it so the heat sink it outside the box. The 2nd pic is of the space above the box.

Wow..tight...yeah no room for that...might get another 6 inches on lights by shortening those cables, might have to put 4 connections in instead of the one..keep a 4 or 5 inch distance from ceiling for airflow and increase the airflow.....with an additional fan and/or more intake holes....

 

[JP1]

What's the temp in the room the tent is in? If it's cooler in the room then in the tent, then you should just need to crank the exhaust up to pull more cool air in. The exhaust goes out the top and the intake is down low? If that doesn't do it, you can add an inline fan for intake down low to make it easier on the exhaust

 

[Upstate_indoor]

What's the temp in the room the tent is in? If it's cooler in the room then in the tent, then you should just need to crank the exhaust up to pull more cool air in. The exhaust goes out the top and the intake is down low? If that doesn't do it, you can add an inline fan for intake down low to make it easier on the exhaust

The exhaust is in the top front corner and the passive intake is in the lower back corner. The room temp fluctuates but stays cooler due to being in the basement. It's reading about 72F in the basement atm.
For spare parts I have 4" duct fans (2 of them) rated at 100cfm but with no variable speed control and a 4" inline duct fan rated at 195cfm w/ the variable speed control to play with.
Do you think popping a forced air intake in next to the passive would help or replacing should i try replacing the passive with a forced air? I just took the 100cfm inake out when I installed the 195cfm exhaust fan.