CFL heat questions.....

Discussion in 'Growing Marijuana Indoors' started by whatuthinkin, Jun 10, 2009.

  1. ok i have read the entire cfl guide on here and have tried looking on other places but havent found this info.

    does anyone have any idea how much heat a lets say a 100w cfl would produce? or any other wattage for that matter. i know that 23-26w dont have hardly any heat but im looking into 2 100-200w cfl lights on top of my plants with 2 26w on the the sides but heat is a huge issue for me. anyone have any idea how much these lights will put off?

    thanks in advance everyone :hello:
  2. bump anyone with personal experiance?
  3. Im guessing your not using equivalent ratings. So saying that I got a 65w cfl, 300w equivalent, and it doesn't put out to much heat. Once you get a few in a small space with no fresh air temps will spike really fast. But as long as you got a source of fresh air you won't have to worry.
  4. I have 4 90w 600w equivalent around (2 400w hps above)my ladies and have about 3-4" from buds and leaves no problem. Then again I have a ceiling fan and not restricted to a closet or small space. the 100 w equivalent CFL's can almost touch the buds.(1")
  5. As was mentioned look at the actual wattage, not the equivilant. I had a 65w cfl that I wouldn't put any closer than ~2.5"

    You should be fine with the lights 3 or so inches away just make sure to have a fan blowing across the plants. Use that back of your hand as a guide. If it's too hot for you, its too hot for the plant.
  6. thats not the problem atm. im using a small gro box. ill have the link to my grow journal when i get home. right now i have 3 23w cfls and a 70w hps. i am goin to all cfl next gro and need to see wich lights to get. space is an issue so im thinkin 2 larger cfl lights on top ant a few smaller on the sides. i have an 80mm comp fan for air intake and a custom made 4" inline fan made from one of those $7 4" fans from walmart for my exhause. have been running the numbers n if i get 2 larger cfl lights i can get more lumens if the heat isnt too bad. thats why im wondering about the heat.
  7. I would think it gives off less heat then the 70 hps
    You should also have a fan blowing on the plants.
  8. sorry for the bad spelling, im posting this from my phone.

    dont worry bout the fans on the plant. they have very thick stalks. also the intake fan is right on them. check out my journal. Mini-Fridge Grow NYC Diesel. just updated with new pics last night. im going to put another fan in the box however to help with the circulation. there r a frew hotspots in my box.

    the thing is i might be able to use 150w cfl but i dont know about the heat of them.
  9. CFLs don't put out much heat. If you are only using 3 or 4, regardless of wattage, your temps will be low. Even if your stalks are thick, a fan blowing air around is beneficial.
  10. #10 whatuthinkin, Jun 11, 2009
    Last edited by a moderator: Jun 11, 2009
    yea thats what i have been thinking. just was unsure on how the higher watt cfls run. haven seen them in person. ok i need to take measurements and see but im thinking of 2 150 watt cfl lights with some smaller ones if needed. im going to be doing scrog next grow so i may not need the smaller ones but i will see once the plant is growing. thinking of one plant n seein how big i can get it.

    does anyone have a good link to a good scrog guide?

    or would i be better off doing a lst grow? im liking the scrog because it will be a more level cannopy.
  11. hi. this my first cab design and have only been testing for a day so i dont really know whats going on but this is what im seeing.

    small space 440mmW (1.5ft) x 440mmD. 2 levels aprox 700mm high each. testing in one grow spac.

    testing with one 130w 6400k cfl (one of the big grow ones off ebay, bigger socket than normal). 60cfm pc fan exhaust, 2 x 80mm pc fan for inlet/circulation (i was moving these 2 80mm fans around for different results, from the inlet hole which is a slit at the bottom of cab about 400mm long by50mm wide, to directly on bulb, towards exhaust etc). ambient temp of around 25deg celcius.

    for some reason i cant get temps below 28degC any closer than about 7 to 8inches between bulb and sensor. ive read in many blogs that even the bigger cfls dont produce much heat, but as soon as i close the door the temps rise to anywhere from 28 to 30 degC depending on the location of the circulation fans (which direction it blows. i can turn the exhaust off and it doesnt make a difference to temps under the light where the plants would be, as long as the inlet fans are both blowing directly on the light. i can get a temp of 27.5degC aprox 8 inches from the big bulb, but with so many fans blowing its nowhere near stealth.

    i was surprised at how hot the space gets. even tho its small from what ive read my fans should be enough to keep temps down.

    any ideas? i imagine the smaller rated cfls probably produce almost nothing. but this big one is intense heat in such a small space.

    im worried that by having to place the bulb around 8inches above the plants, it will no longer be close enough to penetrate and produce..
  12. I have a 125w CFL in with my LED grow, those big bulbs do still get pretty hot, my 60x60x140cm tent shoots up to over 30C with the CFL running...I'd recommend lots of smaller bulbs targetting bud sites.

    Look for a book called "How to grow 8 ounces of bud for less than $100", you'll pick up some useful CFL information from there..
  13. Be careful, little bulbs accumulate alot of heat aswell, been fighting heat from 4 26 watters and.2 54 watters, my whole grow (only been about 3 weeks) when i firsted started temps were at 90+ as an end result I have 2 exaust fans, one 4 inch intake fan 11 1 inch passive intake holes, and a 40cfm pc fan blowing on all 6 of my bulbs and about 3-6 inches away temps are still at 86-88. Im actually thinking about making a plywood lightboard/box with a few intake holes on the side the lights are on (the ballasts will be inside the box)and an exaust fan on top blowing air out of the box thru ducting.
  14. so i accidentally fixed my high temps, for now anyway, i think. i was sizing a u shaped hard foil hood for another light and accidentally left it half over the inlet fan causing the air to be redirected straight across the floor before being sucked up over the fan and through the exhaust.

    with this air baffle running one side of the cab from the inlet fan i am getting steady temps of 25.5 to 27degC depending on location under bulb.

    i will have to update again tho because ive tested at different times of the day. so far promising tho
  15. oh yea , temps seem steady at heights from 4 inches to 8.

    i guess i ive now redirected the air more evenly across the floor of the cab. this air rises more evenly across the lights causing a greater cooling effect.

    what do u reckon?

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