My cab is far too hot !!! HELP !

Discussion in 'Micro Grows' started by bobtheslob, May 3, 2011.

  1. Hi GC'ers,

    I have a 70cm H x 60cm W x 30cm D cabinet I am setting up and I have just installed the 125w CFL and it is running way too hot namely 35C - Currently I have installed one 12" silent PC fan in the top of the cab and one 40mm fan in the bottom.

    I am thinking of ditching the floor fan and adding 3 other passive intakes in the floor and perhaps doubling up the 12" fan as I found one laying around...

    What do you guys advise ? Also I have another 65W CFL to install which is only gonna take the temp higher....

    What is a good temp range for a micro cab ?

  2. Hi there. I'm sure you want advice from someone who actually knows what they are talking about (sorry if this isn't useful to you), but just to share my experience, I have been messing with setting up a small cabinet (~55cm W x 61cm D x 76 cm H) and have been battling heat issues also. All of my ventilation (2-28cfm & 1-46cfm pc fans) must come through the door (intake and exhaust on same 'wall'). With 4 27W-5000K CFL's things got into the 27-33C range without airflow, but with two fans set to exhaust and one to intake, things were quite cozy in the 21-25 C range.

    I wanted better lighting, so I switched to a single 200W Feliz CFL. I don't care what anybody says (not really true but it sounds pretty tough) the big wattage monster sized CFL's get H-O-T! I know they don't put out HID level heat, but I have to get my hand within 3cm of a 27Watter to feel heat while I can feel the heat from the 200W from 15-20cm away.

    Enter massive heat buildup: door closed and fans running temps into the 33C+ range/ door slightly ajar still directing some air in and out and still at 27C/ door completely open with no fans at about 27C also.

    Solution: I reconfigured the fans making the 28cfm at the top of the door exhaust, and the 28 & 46cfm's at the bottom intake; however, I built a secured in place duct to route the air from the 46 to the rear of the cabinet. Things now stay at a pleasant 22C.

    Morals: 1) Shoot for more intake than exhaust (if I read you right the big 12" fan is exhausting while the little 40mm is intake, try reversing this) 2) Make sure that air flow is routed in such a way as to thoroughly circulate air in such a small space (many options, but I fabbed ductwork out of cardboard to fit the compact space and then covered with reflective material)
  3. I will take any advice i can get at the moment buddy so thanks for the prompt reply !!!

    I have a couple of ideas to combat this issue -

    1. Drill three additional holes in the cab floor with a diameter of 4cm and fit these with a elbow joint to avoid leakage of light.

    2. Remove the 4cm fan and direct this little fella at the CFL to promote air flow as discussed - gonna order the ducting tonight and see how it goes.

    3. If the above 2 fail i may switch the 4cm fan for a 12cm fan i found.

    What do you think to the above ?

    Also anyone else got a similar experience to share ?
  4. Aaaaah...think I'm seeing it now (can't tell how ur lights are set up; fixed in place up high or adjustable). I am far from a mechanical engineer, and although I know fluid dynamics is complicated, I'll take a shot. The way it is set up right now, what very limited air is coming through that intake is directed right to the top of the cab. The exhaust is eliminating the heat which is radiated to the top of the space and the intake is supporting that somewhat. There is likely not efficient airflow through the airspace in which the lights are building up heat, and this problem is only compounded by adding more impediments to airflow like containers, plants, etc.

    Good that the exhaust is up high, but I'd strongly consider increasing intake area by at least 4x with perhaps 2 larger intake fans. Ditch the bottom feed and mount them either on opposite sides (elbows like you said if light is an issue), or, if on same side, have one ducted 1\2-2/3 of the way to the opposite side in order to have lots of air circulation through the whole bottom are of the space. This should vastly improve flow and your exhaust will function much better.
  5. #6 valerien, May 4, 2011
    Last edited by a moderator: May 4, 2011
    more powerfull exhaust. i live in az and had heat issues as well. i figured do it right or don't do it at all, bought a 4'' eco plus inline fan from the hydro shop and attached it with some ducting to my exhaust vent.

    it was actually doing such a good job it was lowering my humidity to 29% and getting to only 2-3 degrees above room temp until i added my DIY carbon filter. now i sit around 8-10 degrees above room temp at 35%

    edit: im currently using a 125w feliz 6500k ^^
  6. Larger exhaust. A larger intake will just move the hot air around. You want to remove the hot air. I have a small intake and a larger exhaust. Temps are good, as well as humidity
  7. Right then a quick update just added four 5cm round holes in each corner of the cab and also disconnected the 40mm fan (would highly reco this is it was simply just zapping current from the power unit !)

    Just checked the temperature and it is just over 80F / 27C

    I think once i add the filter / plant it may be too high again but for the moment it is good !

    Quick question if i added a second ac/dc adaptor and glued 2 x 120mm fans together would this in theory increase the exhaust flow ?

    The reason i ask is because i have a spare fan already here and i dont wanna spend any more cash + i hear inline duct fans are noisy !!!

    This needs to be stealth man
  8. [​IMG]

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    Just ordered another AC 2 DC convertor but this fella is 1A for the other fan - I am confident even with a DIY filter this should be all good now :)

    Need to test the cab for a few days and measure temp etc then I think we are looking good !!!
  9. Sounds like things are geting cooler. You can run 2 fans on an ac/dc converter, but make sure that the ac/dc converter can handle the amperage.

  10. Thanks for the advice buddy - i have a 0.2a fan running off a 0.5a supply and plan to use the seperate 12cm fan off a 1a supply that is 0.3a fan :)

    I may even install the 4 cm again too but blowing towards the light or he centre of the cab to further promote the airflow :D
  11. The other reason for getting another acdc convertor is that if you run em under the limit they stay cool too as i surely dont want any more heat sources !

    Thanks again
  12. where did you get your HUGE CFL????i have a 85w one and i love it but a 125w would be sweet run like 2 of those!!!

  13. Thanks for your input - how do you sort the excess noise ? I am concerned about this !
  14. noise was a concern for me as well. The reason I picked up the 4'' eco plus model is because the guy I was speaking to at the local hydro shop said he uses one himself in his room. with a DIY carbon filter seen here (got my supplies at office max, petsmart and walmart, couldnt find it all at walmart), and ducting from one end to my box and the other i have going to the window.

    seen here: (i have since then moved the cool mist humidifer to the other side of the box so there's only about 5 inches of ducting between the humidifier and the inside of the grow box)

    for my window I took a 1-inch think board and cut it down to the height of my window and cut it about 6 inches wide. I drilled a 5 inch diameter hole into the bottom of the board and sanded everything down/painted the side meant to face the outside black. From there I attached a vent attachment designed for a dryer (5 bucks at walmart) and used plumber's glue and high quality duct tape to seal it up. afterwards I put some screen material in the front even though it's still going to be behind my normal screen to give it any extra masking I could and put a black pantyhose leg over the inside of the vent to prevent any bugs from getting through.

    having the main part of the fan in the closet as you can see at night makes the noise no worse than the white noise from the tower fan we have in our room. honestly the cool mist humidifier is the loudest item, i assume because I didn't get an 'ultrasonic' tech type.

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