Ventilation help

dgaf88

dgaf88

New Member
I have a 4x2x4 box and the heat from the 400mh is extremly high. I have what I believe to be about a 40cfm bathroom exhaust fan attached to the outside of the box pulling the air out. I have a hole cut at the bottom of the box that is about 3x6 inches with an oscillating fan in front of it to try and help with the fresh air intake..when the doors are closed the temp will reach high 80s to low 90s so i have to leave the doors cracked all the time which is obviously going to be a problem when it comes time to flower. Is the bathroom fan that I have too low of cfms? Any help with fixing this is greatly apreciated. Open to any suggestions and comments, Thanks.

Oh, and the ballast is located outside of the box allready to reduce the heat.
 
sweet deal thanks for that. It says 32 cfm a minute which it is on the entire time, but it is still so hot in there..is my intake maybe not large enuf? or will i maybe have to get an air cooled fixture and a fan blowing thru a tube to the fixture and then out the other side of the box? Again thanks for the help.
 
Sounds like maybe the incoming air isn't cool enough. If your fan is rated to move enough air to clear the grow space every 1-5 mins. then the problem could either be with the intake too small, or the intake air too warm. It also could have to do with where your thermometer is placed. If it's real close to the light it may show warmer than the actual ambient temp is in the enclosure.

Just my thoughts, one of the more experienced guys may have other solutions.
 
So Ive decided to go with a cool tube fixture which is 4" in diameter. I am going to purchase a 4" squirrel cage fan tomorrow and mount it on the outside of the box forcing air in. On the inside of the box i will have 4" dryer duct connecting it to the fixture and on the opposite side of the fixture have it connecting it to the other outside end of the box. Do i also need another fan pulling the air thru this setup at the end or is the one forcing it thru all that is needed? Also, I am going to purchase supplies for a DIY carbon filter, but i do not know where exactly to mount this? Will I have to remove the bathroom exhaust fan so all the air goes thru this setup? Sorry if these are noob ?s but this will be my first legit grow. Im open to any suggestions and comments, Thanks.
 
dgaf88 said:
So Ive decided to go with a cool tube fixture which is 4" in diameter. I am going to purchase a 4" squirrel cage fan tomorrow and mount it on the outside of the box forcing air in. On the inside of the box i will have 4" dryer duct connecting it to the fixture and on the opposite side of the fixture have it connecting it to the other outside end of the box. Do i also need another fan pulling the air thru this setup at the end or is the one forcing it thru all that is needed? Also, I am going to purchase supplies for a DIY carbon filter, but i do not know where exactly to mount this? Will I have to remove the bathroom exhaust fan so all the air goes thru this setup? Sorry if these are noob ?s but this will be my first legit grow. Im open to any suggestions and comments, Thanks.
Click to expand...

Man, a 400w in a box that size must be cranking out the heat. I've got a 250w in a box of a similar size and although I'm able to control my temps with computer fans, I can imagine that it might be tough.

I have two systems. The primary exhaust and intake fans are on a thermal controller that kicks on when the temps get to 80 and kick off when the temps get to 74. This controls box temps.

Additionally I have a secondary box exhaust that is only used when I need to control smell. (there is a carbon filter and ona bucket attached to it.) When I get into flower I might disconnect the primary for this fan that would always be on.

I've built a smaller filter to the primary exhaust but it's not tested yet.

My light is enclosed with an intake fan and exhaust fan that is only connected to the light. That is the key system for me.

If I had to do it over, I would have probably gone the cool tube route. I think you're on the right track with that.

:Namaste:
 
It sounds to me that you need cooler intake air. I have the opposite problem, I have 1000w hps connected to an inline fan that I am exhausting out one window and in from another but the outside air is at around 25F right now. I can literally have my plants 3 to 4 inches from the glass with almost no heat but my room is only at about 70f now as opposed to 85f before I hooked the inline fan, and I am getting ALOT of condensation on my inline fan and the connected duct work. When i try to draw in air from inside the heat from my light really starts to get up there and I have to raise my hood up quite a bit. I need a solution thats somewhere in the middle.
 
In a space that small temperature variations are gonna happen fast, so the intake suckin in cool air is a must. For instance my space is a 7x6 closet and all I use is a 4in duct fan exhaust with a passive intake thats about double the size of the exhaust. The room I'm pulling intake air from is 68-70, and my grow space never really fluctuates beyond what I've got it set to on the controller. Well except that time my dog decided to lay against the intake vent lol.
 
The air cool tube I got is 6" in diameter. I bought a 65cfm computer fan and mounted that to the tube blowing thru it, on the other side of the tube i have ventilation duct going to the 40cfm bathroom fan that is pulling air thru it. Right now the temp is 84 and hopefully it dont get too much more hot. Do I need ventilation duct going out the back of the computer fan pulling fresh air into the box also?
 
I wouldnt think so. As long as you have openings big enough to compensate for the amount of air being pushed out, there's no real reason to push air in.
 
dgaf88 said:
The air cool tube I got is 6" in diameter. I bought a 65cfm computer fan and mounted that to the tube blowing thru it, on the other side of the tube i have ventilation duct going to the 40cfm bathroom fan that is pulling air thru it. Right now the temp is 84 and hopefully it dont get too much more hot. Do I need ventilation duct going out the back of the computer fan pulling fresh air into the box also?
Click to expand...

I have a fan sucking air in, lower cfm, and another fan pulling air out, higher cfm. Works great depending on the ambient temp of my garage.

Did you mean you have the fan attached to the cool tube? Or mounted away with ducting connected to the cool tube?

:Namaste:
 
giantsfan24 said:
I have a fan sucking air in, lower cfm, and another fan pulling air out, higher cfm. Works great depending on the ambient temp of my garage.

Did you mean you have the fan attached to the cool tube? Or mounted away with ducting connected to the cool tube?

:Namaste:
Click to expand...

Ya, I have the computer fan blowing thru the tube and that has vent duct coming out of the other side that goes to another fan that is pulling air out
 
I'm interested in seeing how your setup works for you in so far as controlling temps go. I'm considering and upgrade to a 400w but am concerned about temp control.

Do you have a grow journal started?

:peacetwo:
 
giantsfan24 said:
I'm interested in seeing how your setup works for you in so far as controlling temps go. I'm considering and upgrade to a 400w but am concerned about temp control.

Do you have a grow journal started?

:peacetwo:
Click to expand...

I went and got some more ducting today and placed that on the intake part of the cool tube. So from start to finish it comes from outside one side of the box and connects to the 65cfm computer fan which is mounted on the cool tube and on the other side of the cool tube there is ducting connected to it which goes to the opposite side of the box and is mounted onto the 40cfm bathroom exhaust fan. So far I happy with the results as it has been keeping it around 78f. Ill take some pics and post them so its not so confusing. Could anyone throw me that link on how to post pics please? As for a grow journal I do not..Ive been thinking about possibly starting one but idk for sure. I just checked the temp on the box and it seems to have rose even more then what it was when I had just the exhaust ducting on there so I took the intake part back off.
 
hey dgaf88.i bought a flower glass pot at wall mart ,for 15$ i went at a windsheild repair shop and add the end cut off for 6$.i got it today .will work on this tonight .i have a 1000w in a 5x9,it gets pretty hot in there..
 

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