*400watt HPS Question* (pics)

Hi again everyone. I have been posting alot on here and you guys have helped me out wonderfully with every problem I have come across.

I recently purchased a 400watt HPS grow light from htgsupply.com (fucking amazing servcice BTW) for flowering possible vegging. My new grow area will be a gutted dresser that i'm using which is about 4' tall x 3' wide by 2 to 3' thick. The inside will also be covered with Mylar.






I am wondering what the best ventilation suggestion you guys would think I can do. I have several computer fans which I can hook to adpaters to work. I know that 400watt HPS do get very warm so Im at a bit of a block.

Anyhelp would be appreciated!!!

to properly cool that small area you are gonna need a 6" inline fan. good luck trying to fit that in side with your light. you are gonna also need a cool tube. for more info PM me as i have several pics of setups just like yours.

relentlessfight said:

I am wondering what the best ventilation suggestion you guys would think I can do. I have several computer fans which I can hook to adpaters to work. I know that 400watt HPS do get very warm so Im at a bit of a block.

Anyhelp would be appreciated!!!

Click to expand...

Forget computer fans they're a waste of time in that space with that kind of heat buildup and mylar will simply reflect more heat as well as light back into the growspace. You're going to have a real battle to control your temperatures in that small sized area unless you put in an efficient 4 inch fan and passive intake system.

I'm not sure i understand exactly how to picture what you're saying. Is there a diagram somewhere I could find?

I like the new Avatar Baby gro...

I am using 450w of HPS (3 150w) in a grow space much larger (4'x2'x6'). I have 2 4" 80 CFM "computer fans," and the sides covered with mylar.

To confirm what Baby gro is saying, after 10 hours of lights on my temp hits about 30c. If I went to 18/6 I am sure I would nuke what ever is in there with heat. When summer comes I will be out of business unless I add AC or a lot more cooling.

Now, consider that your space is 24 cubic feet, almost 1/3 the size of mine (60 CF), what type of heat do you think your going to have to manage?

Last thought: Why not put glass between your HPS and your growing area and vent the area enclosed with your HPS separate from your plant area? This will not address the radiant heat from your HPS (which will be significant), but I would think it would cut down significantly on the overall heat in the plant area.

relentlessfight said:

I'm not sure i understand exactly how to picture what you're saying. Is there a diagram somewhere I could find?

Click to expand...

Here you go bud, had to knock this up quickly.

Thats a brilliant idea!

I have 2 120mm computer fans and a bunch of other ones i could use too. The glass i'm thinking would have to be adjustable in some way i would think, also if you got it to close to the light would this warp it?

personally i would use a 6 inch inline fan.....

I do not think you are going to generate enough heat to "warp" glass. You may wish to used tempered glass. My HPS lights are in a housing with a glass front, so for me the issue is partially solved, though I am conidering this option also.

relentlessfight said:

Thats a brilliant idea!

I have 2 120mm computer fans and a bunch of other ones i could use too. The glass i'm thinking would have to be adjustable in some way i would think, also if you got it to close to the light would this warp it?

Click to expand...

It is a good idea, and they're generally called 'air cooled hoods'. However, even with its air cooling you still have to bring fresh co2 and exhaust stale co2 and keep your temperatures under control.

I'm telling you now, even with an air cooled hood, you'll still need a vent system in that space, preferably with a 4 inch inline fan.

In addition to all the decent advice you've already gotten, one thing that might help, is to make an adjustable shelf for your light. Make it like you would a picture frame, and place a piece of glass into the frame, and place your light on this. As the plants grow, simply move the shelf and light as one.
As you look at fans, think cfm, I use to have a chart showing how much air you need to push to maintain a temp with in so many degrees of the ambient temp, I'll look and see if I can find it.

You need to vent above the grow light, and below it too. Intake should be at the bottom.

I'm back, kinda blazed again too, sorry.
I did find this for you to use.
Here’s an equation that will nail down your CFM ventilation needs.

Attach the frame directly to the bottom of the reflector?
I figured it would be a good idea to put the intake would be near the bottom and exhaust near top as hot air rises and cold air falls. That would be great.

Now I just need to think how to put all this in that area...haha hm...

Thank you very much for the idea, videoman!!

buy remember its always a good thing to have extra CFMs if you need it....plus if its to much you can buy a fan speed controller for like $30.

oh shit! nice!

Another twist on the "frame" idea, and I'm only thinking outloud right now, so bare with me, is make a frame that you can slip the piece of glass into, but get a piece of glass cut long enough to fit side to side,
however lengthwise, have it cut so that it is 6" too small.
Now you have an access to suck air from below (your grow area)and out your exhaust.
I've had good luck with $12.00 bathroom exhaust fans from home depot.
You could place one of these, rather than against the side wall, against the top so it only intrudes into your space about 3", also place it above the end of your newly built frame/shelf that is open to the grow area.
I hope I made sense to you, I'm having hard time right now, I'm testing out some brownies I ate earleir today. lol
Peace

What I did...which worked extremely well, was hanging a fan at the same height at the top of my plants. The air movement brought the temp down on the tops of my plants, which worked perfectly. The temp where the fan was not blowing was 87 degrees, the moving air from the fan was 76-77. Just a suggestion

videoman40 said:

In addition to all the decent advice you've already gotten, one thing that might help, is to make an adjustable shelf for your light. Make it like you would a picture frame, and place a piece of glass into the frame, and place your light on this. As the plants grow, simply move the shelf and light as one.
As you look at fans, think cfm, I use to have a chart showing how much air you need to push to maintain a temp with in so many degrees of the ambient temp, I'll look and see if I can find it.

You need to vent above the grow light, and below it too. Intake should be at the bottom.

I'm back, kinda blazed again too, sorry.
I did find this for you to use.
Here’s an equation that will nail down your CFM ventilation needs.

Click to expand...

Videoman, I don't understand the temperature in the CFM equation here. Is that the difference between ambient and desired temp?

Yea I dont really understand the equation either man sorry. Now as for that part with the glass... do you mean have like a 6" gap like for example at the front so it would suck air from the bottom where the plants are to the top and then to an ehaust? So basically what i'm saying is a glass shelf with about 6" of space missing from the front or rear whichever. Is this what you mean as well? If not what do you think about that...i could move it up and down as needed that way!

relentlessfight said:

Hi again everyone. I have been posting alot on here and you guys have helped me out wonderfully with every problem I have come across.

I recently purchased a 400watt HPS grow light from htgsupply.com (fucking amazing servcice BTW) for flowering possible vegging. My new grow area will be a gutted dresser that i'm using which is about 4' tall x 3' wide by 2 to 3' thick. The inside will also be covered with Mylar.

I am wondering what the best ventilation suggestion you guys would think I can do. I have several computer fans which I can hook to adpaters to work. I know that 400watt HPS do get very warm so Im at a bit of a block.

Anyhelp would be appreciated!!!

Click to expand...

i would, since this a real small space put a computer fans right at the lamp and a bigger muffled fan to the box. you won't need a heating in this set up

ngtybear said:

I do not think you are going to generate enough heat to "warp" glass. You may wish to used tempered glass. My HPS lights are in a housing with a glass front, so for me the issue is partially solved, though I am conidering this option also.

Click to expand...

hey bear, you will get some heat issues with your lamps to if you run those for 12-18h, believe me those things will get flaming hot with in some minutes, especially in cramped space!