Reducing cab temps - help!

[funkervogt]

Hey all,

I've got a flowering cab that's wayyyyy too hot at the moment. I suspect the trouble is my cooltube not flushing air like it could be.

The picture is pretty descriptive - the temps are sitting around 85-88 F depending on distance to the cooltube. The 250W cooltube is hot to the touch. My room temperature is about 70 F.

A PC fan is venting the cooltube, and a 190CFM exhaust fan is flushing the cab (that 4-inch vent hanging in front). I have 6 2-inch holes drilled to allow passive intake. They are filtered with pantyhose.



I'm thinking of upgrading to one of those 65CFM Sunleaves fans (installed just before the cooltube to push air through) but wanted to ask everyone's opinion before doing this.

Whaddya think? I'd like to get this done soon to start flowering!

Regards,
FV

 

[pinkskunk]

i have one of those fans and i dont use it,its a 10 inch. i have two six inch fans in my tent and a cool tube my set up goes odor sok with six inch pulling air throughthen some duct to cool tube then some more duct then another six inch exhausting. during the middle of summer i had a few hot days like 85-90 but it didnt bother my plants any. i can have my light sitting bout three inches from my plants with this set up cause theres so much air running through the tube it doesnt get hot realy and im using a six hundred watt by the way in a 3x3 tent

 

[fully baked]

If I were you, I'd run the two fans you have now in series through the cool tube. Open up the bottom of the cool tube so it's exhausting air from the cab, and place a fan on the intakes blowing up for air circulation around the tube.

That should drop temps a little bit I think...

 

[DiscoBiscuit]

Yo funkervogt, what kind of exhaust fan do you have? You'll probably need at least ~150 CFMs, especially if you use a carbon scrubber.

If you're exhausting 4 inch duct, that's a 12.56 sq inch hole (assuming a round hole.) You'd have cooler temps with ~25 sq inches of intake. Looks like you've got four 2 inch holes in the floor but that's only 12.56 sq inches. Cut four more of those 2" holes or one 4" hole for additional intake. A fan blowing on the hot spot or between the bulb and canopy may be required.

 

[funkervogt]

Yo funkervogt, what kind of exhaust fan do you have? You'll probably need at least ~150 CFMs, especially if you use a carbon scrubber.

If you're exhausting 4 inch duct, that's a 12.56 sq inch hole (assuming a round hole.) You'd have cooler temps with ~25 sq inches of intake. Looks like you've got four 2 inch holes in the floor but that's only 12.56 sq inches. Cut four more of those 2" holes or one 4" hole for additional intake. A fan blowing on the hot spot or between the bulb and canopy may be required.

I actually have 6 holes, but I see your point. I'll drill two more holes to improve air flow.

I have a 190CFM fan venting the whole cab, a PC fan (probably 30CFM) on the other end of the cooltube sucking air out.

If I were you, I'd run the two fans you have now in series through the cool tube. Open up the bottom of the cool tube so it's exhausting air from the cab, and place a fan on the intakes blowing up for air circulation around the tube.

That should drop temps a little bit I think...

Hey fully baked! I had actually done this before but was unsatisfied with the temperatures (and the space limitations). I'd like air to circulate up and around the cooltube as well to give a good flow on the plants. Right now I'm testing out a setup similar to yours, with a fan at the bottom to push air up as well as to circulate around the cooltube (sort of like your design). I'll report back on the temps when I'm finished.

Thanks all! Keep the good advice coming

 

[funkervogt]

Okay, so using fully baked's cab technique from his thread I reduced temps significantly (now holding steady @ 81 degrees 2 inches from the cooltube). This is outstanding as I don't have to buy anything new.



These C99 BX girls go into flower TOMORROW!!!

 

[Matanuskan Flo]

yea, i also think u need to have more intake, but also, your pc fan exhaust is the issue. it is way to weak to effectively pull the hot air out. also, b.c the height of the cab is so high, the heat will build up in the higher areas. if you could lower the ceiling somehow, that would reallllly help. by the hieght of your light, you don;t need more than but 4ft really of height.

 

[fully baked]

Thanks to Disco Biscuits math, I bet you could drop it some more by adding those intakes like he said.

Great news though funkervogt!

I still see your second duct up top. Are you still running the fans seperate? The reason I ask is because if there isn't an adequate flow of air through the tube, it will still create hot spots around the bulb. The more air flowing through the tube, the more hot air that is immediatly discarded from the cab.

Keep me updated,
FB

 

[funkervogt]

if you could lower the ceiling somehow, that would reallllly help. by the hieght of your light, you don;t need more than but 4ft really of height.

It's already at 4 ft I could lower it, that's not too hard (basically another shelf with a hole cut in it).

I still see your second duct up top. Are you still running the fans seperate? The reason I ask is because if there isn't an adequate flow of air through the tube, it will still create hot spots around the bulb. The more air flowing through the tube, the more hot air that is immediatly discarded from the cab.
FB

I am using two exhausts and yes, this is not ideal. I am going to switch to basically doing exactly what you do with a single exhaust through the cooltube. While I wanted to do the cooltube separately, I see why this is an effective method now. The fan ends up blowing air up and around and finally exits through the cooltube.

I'm also worried about those hot spots like you guys mentioned... I'll see what I can do to lower the ceiling.

 

[funkervogt]

Okay, so the verdict is pulling all of the air through the 190CFM fan through the cooltube. It is open at the bottom, and a volcano fan blows from beneath. I have the setting on medium as I don't want to blow the fuck out of the plants.

The temps are remaining fairly steady - 77-80 degrees depending on the placement, but no more than that around the plants.

At the moment I'm not going to lower the ceiling because its a pain in the ass. If I notice heat buildup in a certain location I will, but for the time being things seem okay.





EDIT: Oh yeah, I added 4 more 2" holes.

 

[BLUNToPOTomuss]

glad you got it worked out Funker, DB is money on the intakes! remember the passive intake rule.... 2-3 times the size of your exhaust hole. Also, 1 4'' hole is equivelent to approx 6 2'' holes. Id go with atleast 12 2'' holes MINIMUM! if you go a few more your exhaust fan should pull a bit more air through your tube and run with less restriction hence cooling your bulb even more.,

Good luck!

 

[funkervogt]

glad you got it worked out Funker, DB is money on the intakes! remember the passive intake rule.... 2-3 times the size of your exhaust hole. Also, 1 4'' hole is equivelent to approx 6 2'' holes. Id go with atleast 12 2'' holes MINIMUM! if you go a few more your exhaust fan should pull a bit more air through your tube and run with less restriction hence cooling your bulb even more.,

Good luck!

Okay, that's great advice. I should note I added some holes...

I have one 4" hole surrounded by 8 2" holes in the center. On the outside I have 2 more 2" holes, though, these are covered by plants it seems. The fan blowing upward is sitting in the center 4" hole. I imagine this is acting as an active intake of sorts for the center holes.

Do you think I should add more holes around the outside or the wall?

Thanks again,
FV

 

[DiscoBiscuit]

FV, looks like you've got enough intake. I like the fan under the open tube, looks like it'll grow lots of pot, dude. Nice work.

 

[pinkskunk]

SORTid!!

 

[BLUNToPOTomuss]

Sounds great!!

 

[funkervogt]

Okay, I did a few more adjustments. I created a raised floor with more holes to prevent outward airflow under the plants. I also included a better view of what's happening under the cab - that 4" hole is not filtered as the fan sits in it - the other 2" holes are filtered (even the one on the far left, but from under... long story).

 

[BLUNToPOTomuss]

I really like the shelf and all the holes!

The only advise I would give is drill MORE holes in the shelf so your pots dont cover most of them. With that shelf you cant have too many holes! Improved airflow past that shelf is going to be crucial.

You are definately on the right track!!

 

[funkervogt]

The only advise I would give is drill MORE holes in the shelf so your pots dont cover most of them. With that shelf you cant have too many holes! Improved airflow past that shelf is going to be crucial.

I added about 10 more holes - on the inside and around the edges. and I think this is as many as I can do without the shelf giving way

So far temps seem to be okay (~80 degrees or 7 degrees over room temp). I like the fact that the air is coming from below and then moving above. What I might do is install a big fat box fan down below and put in more intake holes to improve upward airflow, but right now this feels right.

 

[hoosierdaddy]

funkervogt kickin it hoosierdaddy style! I like!

Are you set, or will you need some tweaks in the summertime?

 

[funkervogt]

funkervogt kickin it hoosierdaddy style! I like!

Are you set, or will you need some tweaks in the summertime?

I might need some tweeks. I'm in the midwest and run at night, so I imagine I can open a window or something and regulate temps that way. The big risk is the room heating up too quickly, plus fresh air exchange would be nice. I'm in the midwest.