[BLunTeD4LifE]

hi peeps...

i wanted to ask a question regarding temperatures... ive just recently finished building my new grow box, its lit up with a 400w HPS light, and i have a 100mm extractor fan with a carbon filter fitted to it to remove the hot stale air... the fan shifts 227m3 per hour...

heres some pics of the cab im referring to.,..



this next pic here is just to show u what im doing for air intake...



i figured that the fan im using should be able to draw in air from that long hole ive cut at the bottom right??
that intake hole is like 2.5 inches wide, and it runs down the whole length of the cabinet...

i am going to be putting some material on the inside that is light proof so when they are in their dark period i will just take the flap down and velcro it shut over the air intake hole...

anyway.. this is now the second day ive had it running... when i woke this morning the temps were like 34C... and the plants really didnt look happy in there at all...

i m really not sure as to what can be done next to try and solve this problem... the temperature in the room that this cab is in is like 22C... so its not the ouside heat thats causing the box to be so hot...

i figured that a 400w light should be fine in this space, because i have seen profresionally built grow boxes that have 600w lights in them, anbd they are just slightly bigger than my box...

would having a sheet of toughened glass on the reflector make any difference??

i am planning to buy a cooltube reflector as soon as i get the money.. but thats not gonna be for like another month or so... so i thought i would see if anyone here could recommend anything that i could do in the meantime to lower these temperatures...

any help would be gladly appreciated folks...

thanx in advance...

I'm trying to convert in my head what 227 cubic meters per hour is in cubic feet per minute (cfm) as I normally do. So let's see....227 meters to the third power= 3X number of feet per minute to the third power....the third powers cancel each other out....divide 3 by 227....about 76.........so you've got about 76 CFM. I did that all in my head so I'll say my final guess is off by about 25, so that puts us at a nice even 100 CFM (cubic feet per minute). 100 cfm, although your space is small, is too slow for your 400 watt light. You should keep that fan and just air cool your light and get a bigger fan for the ventilation of your box.

*edit* Instead of trying to sound like I'm good at math what I should have said is this: keep your 100mm fan and use it to air cool your light. Then buy another fan to vent your box with.

[BLunTeD4LifE]

the size of the box is 3ft x 1.5ft x 5ft... i was thinking... if i were to stick the box beside my window... take some more ducting and stick it into the box and then stick it out of the window... would the fan be able to also draw in air from outside via the ducting when the boz is sealed??

[Old Soul]

You definitely need a bigger fan and an air cooled reflector, and then you could put a 600w in there.

Peace

Old Soul

[BLunTeD4LifE]

but.. i dont want to put a 600w in there.. i want to use my 400....

[Maj.PotHead]

https://www.icmag.com/ic/showthread.php?t=29341
i use it in my cab and 400w hps if you can find a fan like this in your country your set, but you sould get stronger exhaust. if you use glass make sure its tempered really is better to just buy it where your light came from.

[MTF-Sandman]

Are the temps you're measuring the ambient temps or the radiant temps? Might wanna put a fan blowing directly on that light to help remove some of the heat buildup as well...

BTW, that fan is pulling about 133cfm which should be OK for a 400. I keep a 1K closet cool with 2 265cfm daytons (1 aircooling hood and 1 pulling through scrubber) which aren't working at full potential due to backpressure....temps stay within 5f of ambient room temps.

[Guest423]

is that a can fan? you could go buy an air cooled hood for your light, that would help on the heat problem big time.

Nice looking cabinet, Blunted4life! Isn't it a bit large for a microgrow? LOL

OG had some good design spec's to follow. If I remember right, a naked HPS bulb needs about 1 CFM per Watt to keep the temps within 10F of ambient. Your 227 m3 fan will push 480CFM unrestricted. The easiest fix is to remove the scrubber. This causes two problems. You're now running without odour control, and there will be lots of stress on the plants from basically a high wind.

A ventilated hood will drop the cooling requirements down to about 0.3 CFM/watt for the growbox. To cool the hood, 0.2 CFM/watt is needed. So basically, if you use a scrubber -> hood ->fan ->exhaust, about 120CFM is needed. This is the way to go!

The big unknown is how much airflow can you get through your scrubber. Most of those CAN filters are designed for max airflow at 0.75 in of H2O. I believe most blower type fans can produce 1.5 in H20 static pressure. Check your fan manufacturer's website and you will find a curve of flow vs pressure. I'm guessing but your fan/scrubber combo is probably putting out 200 CFM.

The other option is to oversize the fan to force the air through the scrubber. Typically the fan is oversized from 1/3 to 1/2 the scrubber rating. You didn't give us the scrubber spec's but I'd guess that a 600-700 CFM blower would be needed.

It looks like you are using a 6" exhaust. The intakes need to be 2 x pi * 9 = 57 sqin.
Your 2.5" intake should be at least 23" to allow for maximum flow.

[BLunTeD4LifE]

thanx a lot guys... i knew if i just gave this place time the real answers would start flying at me!!!

this forum is the best cannabis growing forum on the net!!!

u guys are great, and always provide the best answers...

well red greenery.. its a whole lot smaller than what i have been working with in the past.,. most ppl upsize their growing systems but i wanted to downsize!!!

i guess maybes it is a bit big for a micro grow... but i didnt know where else to post this, and i have seen a few cabs that look similar in design to my one on this board...

ive now got my 12" fan blowing right onto the bulb on the highest setting... i have to leave the doors open a little bit also... now i got the temps down to a steady 27C...

but really the idea of having my grow in this small closet was so the doors could be shut!!

so i have a few things that i can be trying now....

thanx again peeps...

P.S. i found these vertical growing coolshade reflectors... now as far as i can see the only diff from these and a horizontal cooltube is that these ones dont have the internal reflector... and they are also missing a hook from one end to hang it up...

https://www.growell.co.uk/p/3466/Vert...eflectors.html

there isnt any reason why i couldnt buy this and use it horizontally is ther??

i can just fix the reflector that i m using just now onto the outside of that cooltube to reflect light back down onto the girls... i mean its only £48 for these vertical tubes,,, where as when i was pricing the horizontal ones with the internal reflectors they were damn near £90!!!

that cooltube will work out fine wont it??