Electrical Question??????

madman

I have two 120MM 12V pc fans one for intake and 1 for exhaust. They both are rated !2V and draw .66 amps. The only power supply I could find were 12V 1amp. My question is: Would it be better to run both fans from 1 power supply or would it be better to run each fan on its own 1amp supply? I tried it both ways, when they are run seperate the fan speed is much greater. I just want to get as much life out of the fan and supply as I can. With both fans running today which is a hot and muggy day, room temp is 82 and growbox temp is 84.

Thank in advance!!

Madman

jangel

You need the most power you can get from those babies so run them seperate. It is still pretty toastie in there. No way you can use both for exhaust and add a passive intake? That would cool it off better and double use your fans. Passive air will always move faster than a fan, for intake. It will fill any vacuum and the fans will exhaust better. Just my opinion, but you might find it will get too hot.

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Life,
j-angel


My Little Grow LST'ing w/Hardware

My Outdoor Odyssey 2008 BONSAI MUMS

Cloning a Flowering Plant My Little Grow Blueberry

hollah

Hi,

i have just completed my stealth box today and put my babies in.

what i have is the same as yourself 2 120mm fans 1 for intake and 1 for exhaust (keep eye out for my piccies going up over next couple of days)

what i have done is i took a PC atx powersupply bridged the pins 13 + 14 so that it does not need a motherboard to work.
From there i have access to add which ever peripherials i may require using 3.3v, 5v, or 12v
i am testing at the moment and today is rather hot and humid (uk) and my box with envirolite 200w flower is still managing a steady 29 degrees. (this is still quite hot i think, but that is the temperature of this room as i have pc's running and also the central heating system is in a cupboard in the same room).

as a pc engineer it made sense for me to use a PSU (modified for my CFL's) i have added an extra port on the chassis of the psu to accomodate the cfl's IEC adapter rather than running it back out of my box. (cosmetic really and maybe allowing for 2 lights to be run from same psu (veg + flower, possibly later on)

my piccies will show better what i mean - just need to find my darn mini usb cable to transfer...!

ISO2BWELL

Madman,

Do the math. .66 Amps x 2 fans = 1.32 Amps, which is 30% over the rating of the power supply. Bad idea.

Run 2 of the power supplies..only thing to do.

ISO

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madman

I put a fan in the window of the room that my grow box is in to exhaust the hot iar in the room. Temps have been staying around 80 and that is towards the end of the light cycle. During the night they drop to 75. I have a smaller fan to circulate the air inside the box that runs 2 hours on 2 hours of all during the day and night. Put plant on 12/12 on 6/27 and is already showing lots of hairs. I have a question, this plant is pretty dense, big fan leaves everywhere. It is hard to see to the other side of the plant! Should I remove some of the fan leaves so light can get to some of the bud sites or just let it be and see what happens?

Thanks for all your help.

Madman

p.s Jangle, the plant I put outside isn't showing any signs of flowering yet, but boy has that thing taken off. I can't believe it with all the rain we have been gettin.

ISO2BWELL

Madman,

Sounds like you have the handle on your temps. Great job! Always a challenge for me too when summer and high temps hit...and I live in cold country..LOL.

The circulation fan in your grow area needs to run 24/7. The plants are transpiring unwanted stuff, and you need to keep that air around them fresh or they sit in their own...well, nasty stuff. Anyway, it ain't good for 'em, so run that one 24/7 if you can.

As for the fan leaves...well, that's another thread or 5 in itself. Do a search for fan leaves as the title and you'll find plenty of discussion on the topic.

ISO

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jangel

As far as the plant outside, it will take what time it needs to flower. Now it is doing a stretch, then it will flower.

And as far as the fan, what ISO said. LOL! It will help cool it down also. and keep the worst of the heat off your plant. If the plant is thick
try bending or tucking the big fan leaves under branches and out of the way before you take those food factories away. In my opinion, the plant needs them to make food and support the buds. As ISO said, do a search and read up on it. Just like many things, there are 2 schools of thought on this. If you have a lot of lower branches try LST'ing the taller ones and that will bring the hieght down and add light to those bud sites. You want a canopy of fairly even hieght so the shorter bud branches will catch up to the taller ones.

Also, the lowest branches that will not get light can be removed and used for clones or just saved as trim. This will help with air movement around the base of the plant and this way you can avoid nasties like mold etc.

__________________
Life,
j-angel


My Little Grow LST'ing w/Hardware

My Outdoor Odyssey 2008 BONSAI MUMS

Cloning a Flowering Plant My Little Grow Blueberry

green_nobody

since you are in flower now I would stick to what Jangel suggested and do some LST on the top branches to get some light for the lower ones - for topping it is a bit too late now as this would also mean to cut away developed bud sides now. On your next grow you might top them a few times before putting them into flower.

on the 12V supply, i would try to get a 12V door bell transformer or use the power supply from an old PC. there are also small 12V transformer especially for 12V fans as well but those are a bit hard to find. just go to the next bigger hardware or building supply store and ask for a build-in 12V transformer for some light or fan that provides stable 4 amps, should be in the 20-40 bucks range normally.

__________________
Keep the gun oiled and the thumb green!

http://www.pch.gc.ca/progs/cpsc-ccsp...Canada-eng.MP3

Framster

Hey Madman,

Just on the side of caution, I would get another transformer to run each fan independently.

Looks like you got a handle on the heat issue, but if temps get any higher, I would suggest using both fans for exhaust and have a passive intake at twice the diameter of the fans exhaust to minimize any back pressure or resistance. After talking to a HVAC guy, he informed me of the 2-1 ratio, regarding the intake v. exhaust size comparison. Also, air flows better when you radius your light trap to where the air travels through an "S" rather that around square corners.

jangel

What he said......LOL!
I have a 6 inch vortex exhaust. To balance that I have a total of 12 inches passive air intake....double the width of the vortex....so that is what you need as I mentioned before, air will not allow a vacuum so it will come in faster through a passive intake. It can be blocked or slowed down by an intake fan. That is not good.

Thanks framster ..... you explained it perfectly.

__________________
Life,
j-angel


My Little Grow LST'ing w/Hardware

My Outdoor Odyssey 2008 BONSAI MUMS

Cloning a Flowering Plant My Little Grow Blueberry