Heat problem?

Ok heres the deal, I have just built A grow chamber out of a olf KFC chicken warmer. The setup is just a 400watt MH lamp and a reciprocating fan. The unit it is within is about 5' high and 2'X2' maybe a few inches wider. Now heres the problem the heat reaches over 100F im not to sure but i think that will fry my plants. any ideas on how i could vent out my unit? without drillin or cutting any bigassed holes that will alow light to escape....

Any help will be greatly appreciated, thank you

 

400 watt MH is enough for 8 square feet - that's a lot of heat in a box only half that size! I know what it's like to try and grow with temperatures regularly over 100f. - believe me, you don't want to go there!!! What you need is forced ventilation and, maybe, an air-cooled reflector to keep your plants "finger lickin' good". Are you worried about losing light from your plants or is the light a security risk? You have plenty of light to spare for a 4 square foot box! Go ahead and cut the holes for a proper ventilation system. Deal with the leaking light if you have to - it's better than baking your plants.

Look back through the old threads in the "Growing Indoors" Forum and the "Growrooms and Greenhouses" Forum, you will find lots of good ideas for ventilation.

 

I'd put a good extractor fan high in your room. You then have the choice also of connecting it to an air cooled reflector. The extractor fan itself will reduce both the temperature and humidity as well as removing the smell its really an essential piece of equipment.

 

Hey Rickety!

Listen to B'man he has a great deal of experience with indoor growing!!
Another thought occured to me as I re-read your 1st post. Is this chicken warmer of your's insulated? If it is; then it is truely like an oven! The only way to get rid of the excess heat is by forced ventilation of some kind. Without any real heat loss, through the walls of the box, the heat will just keep building up; I reckon. The source of heat is obviously the 400w MH - an air-cooled reflector or a "cool tube" will suck most of the hot air right off of the light before it has a chance to heat up the box too much. A good A-C reflector may cost $$'s but they come highly reccomended.

Check this out - DIY instructions for a cool tube:
http://www.drugs-forum.com/growfaq/1432.htm

With most of the heat removed before it's a problem, the remaining ventilation requirements should be minimal. Don't under estimate your plant's need for "fresh air" - you need to get a constant supply of oxygen and CO2 inside the box, as well as getting rid of the heat!

 

Ok well im in Northern canada in the middle of the nowhare, so alot of these things you speak of are quite hard to come by.....i was thinking about using a 18 inch section of ducting removing about 45% of the front of it. Mounting my lamp socket within this and sticking 4inch ducting hose on both ends, with 2 12 VDC PC fans sucking and blowing air across the lamp....any idea if this will work? or will i lose to much light by having only the bottom of my ducting opened? I would just use glass tubing for the lamp holder but i have not been able to come by any that seems usabull........

 

Hey Rickety!

Remember the old saying, "Necessity is the mother of invention", I think Frank Zappa said that (long story). Anyway, it sounds like you're making your own version of a cool tube - COOL!!! If you paint the inside of the ducting, around the lamp, with some heat resistant flat white paint you shouldn't lose much light at all.
If you use both fans as exhaust fans to suck the hot air out it will work twice as efficiently. It didn't make sense at first - but the guy that wrote the article I was reading was a heating/air conditioning installer. He explained it this way: If one fan is blowing in 100 cfm and the other fan is blowing out 100 cfm; you are only moving a total of 100 cfm. On the other hand; if both fans are blowing out of two seperate ports at 100 cfm each, you are moving a total of 200 cfm. As I recall; the passive air intake, near the bottom should be at least 30% bigger than the combined exit ports area, so a 6" square or a 7" round hole would be about right.
Of course this is based on the idea that one end of the "ducting reflector" is blocked off and you're just sucking air in though the light cutout - that would make it an air cooled reflector. If you do have some kind of glass tube or lens in there; the other end of the ducting would have to be left open. Either way, it sounds good to me. I hope this gets most of your damn heat out of there!!!
If you are going to use this as a straight up cool tube (intake tube from the outside to the lamp enclosure, exhaust tube back to the outside of the box - a "sealed" system); then you will still need some good ventilation to get fresh air inside the box. I hope I didn't make this sound too complicated. If you run into trouble - we're out here with our ear to the ground! Good luck!!!