First grow, CFL's Temp question

First post and just want to say ive learned a lot fromt he forums. Seems to be a great community. I just have a quick question as my first cfl grow gets underway.
I have 5 plants in a 3x2x4 stealth homemade box. The box is in my closet in an airconditioned house. The house stays around ~75 but drops to ~70 at night. I started the room with just 5 26w CFLs. Today i added 5 more for a total of 10 26w CFLS. The problem i am having is, the air outside the box in the closet is around ~78-82 (based on digital thermometer). I have a 250cfm fan blowing air in with passive exhaust. Obviously this is plenty of air since it is cycling the air in the room over 10 times a minute. I have a wireless thermometer and i have tried many different places within the cabinet and get many different readings.

I honestly dont know which temp i should be relying on. At soil level which is pretty much where the foliage is right now sometimes it can read as high as 93 degrees. On the floor below the pots it can read ~82. At the very top it reads somewhere around 90 degrees. I honestly have no idea why the temps are so high. I am sitting 7 feet from this thing and its 77 degrees right here and im pushing about 15 times the volume of the chamber through it each minute. I would appreciate any help you can give.

Thanks

Can u get us a pic?

Sounds like your fan isn't working so well.
You should try using your fan as an exhaust rather than an intake. It seems to work better.

You could also check the box for stagnant pockets of air that aren't captured well into the flow from the fan. Add additional fans (exhaust) to some of those areas.

Though the cfl light itself has very little heat their balasts are giving off the heat.
It may be better to use 4 higher watt bulbs to help with the heat. I'm not sure how much difference the higher wattage bulbs are but with using 4 more lights you have doubled the heat given off from your lights.
Do you have temperature readings from before you added the extra lights?I think its best to go with the temps at the foliage.
If your temps are that high (93) you should have some CO2 in there with the plants.

I can get a pic but it will probably be tommorow. Before I doubled the bulbs the temp was around ~85 which im fine with because i do plan on running some CO2 in there. Also in regards to the CO2 can you ever start it to early? I germed and planted ~48 hrs ago and they have already come up and through with leaves. Also im not sure if it matters but i am growing PPP which ive read is a very hearty plant and could possibly be alright in slightly higher temps.

thanks for your help

It works best if your intake is placed low in the system, where the coolest air is, and the exhaust is placed high in the system, where the hottest air is.

Thanks for confirming what i was thinking scranny. I have my intake at the absolute lowest point and venting at the highest

Heat rises. lol

633csi- It seems like all of your proportions and variables are correct, you might want to think about what thelittletruck said and switch that 250cfm fan to an exhaust rather than an intake. I run a very similar stealth cab (little smaller) with 250w HPS and use a 270cfm inline as an exhaust through my light, but opposite as you I have passive intake and active exhaust. So far my set up has worked great for me and I am running at slightly higher ambient room temps than your closet.

My rational would be that even though you are pumping lots of air into the cab, there is not a vacuum effect happening for the hot air at the top of the cab because there is no negative pressure on the outside of the cab. If you have oscillation within the box and forced intake the hot air could swirl around giving you higher temps compared to using all of that force to simply suck out hot air. Once you switch to pulling hot air with the fan, the intake at the bottom will be a vacuum on the outside and pull cold in like a jetstream.

gimley said:

My rational would be that even though you are pumping lots of air into the cab, there is not a vacuum effect happening for the hot air at the top of the cab because there is no negative pressure on the outside of the cab. If you have oscillation within the box and forced intake the hot air could swirl around giving you higher temps compared to using all of that force to simply suck out hot air. Once you switch to pulling hot air with the fan, the intake at the bottom will be a vacuum on the outside and pull cold in like a jetstream.

Click to expand...

It's simple osmosis...the exhaust fan creates a vaccuum at the top of the box, and the air below it has to rush to fill it, which in its place leaves its OWN vaccuum, and the ambient air pressure around the box causes air to flood into the box to fill the vaccuum created by the air at the bottom of the box rising to the top...DUH! lol

sorry to ask but would a 250watt in a bud box 3x2x4 be ok im undecided weather to use a 400watt with a cooltube or just a 250watter