ventilation question

K

khumbivectus

Member
Hello, everyone. This is my first post. I tried doing a couple searches to find the answer to my question, but to no avail. I have a closet I want to grow in that's 63 cubic feet (29"x39.5"x95"). I'm thinking about bringing cool air in from the crawl space through the floor and venting it out through the attic with some 6" ducting and inline fans. I'm getting a 250W cool tube hps light that'll have separate ventilation.

Questions:

1. Is it necessary to cut holes in the floor and ceiling for ventilation in a space that small, or do I just need to open the closet a few times a day? I am planning on giving it more than enough attention.

2. If I do go through with the aforementioned ventilation system, how many cfm do I need for the top and bottom?

3. Should the intake fan have a higher output than the exhaust?

Thanks in advance. I'm very glad I found this forum.

Sincerely,
G.
 
zippythehippy

zippythehippy

Active Member
i cant help on the size of fans etc but when your lights are off your plants will still need fresh so theyll have to be on 24/7 also when in flower if you yurn your extraction off its gonna smell
 
Mother's Finest

Mother's Finest

Well-Known Member
Welcome to the forums. First off, the plants need some constant fresh air, both to breathe and to regulate the temperature. Even if your cooling system for the light actually makes the lamp cold to the touch, that coldness isn't transmitted to the grow room's air very well without airflow. The radiant heat being emitted by the light is transmitted very easily, however, and heats the air & the plants in the grow area.

The plants need air to breathe as well and this is actually more important at night, just like with CO2 enrichment.

Every grow should have three types of airflow; air to cool the lights, fresh air for the plants to breathe and internal air circulation that helps disperse heat & encourages stem thickening.

There doesn't need to be both intake and exhaust fans for most air circulation systems. It's almost always cheaper to just get one fan a size up from the two you would have used.
 
L

Luke

Well-Known Member
Mother's Finest said:
Welcome to the forums. First off, the plants need some constant fresh air, both to breathe and to regulate the temperature. Even if your cooling system for the light actually makes the lamp cold to the touch, that coldness isn't transmitted to the grow room's air very well without airflow. The radiant heat being emitted by the light is transmitted very easily, however, and heats the air & the plants in the grow area.

The plants need air to breathe as well and this is actually more important at night, just like with CO2 enrichment.

Every grow should have three types of airflow; air to cool the lights, fresh air for the plants to breathe and internal air circulation that helps disperse heat & encourages stem thickening.

There doesn't need to be both intake and exhaust fans for most air circulation systems. It's almost always cheaper to just get one fan a size up from the two you would have used.
Click to expand...
This is good solid advice.
 
Shangeet

Shangeet

Active Member
1: yes, you do need to exhaust your light but you dont need the intake

2: a 4" can-fan will be plenty to keep it cool

3: just a passive intake through any existing spaces is enough

4: you only need it on during the day but i would run it 15min every hour to keep the humidity down especially during flowering
 
Nitegazer

Nitegazer

Well-Known Member
By way of clarification-- ventilation achieves three major objectives: reduction in temperature, replenishment of CO2 and reduction of humidity. When the lights are on, ventilation is needed for all three of these reasons. When the lights are off, the only reason you will typically need ventilation is to reduce humidity-- requiring much less air flow. If you want, you can either cycle the fan for a couple minutes every hour (the timing depending on humidity levels), or you could get a switch that is triggered by humidity.

It's a question of $$ and stealth. I tend to run my lights at night, when there is a lower chance of 'discovery' by visitors, and I like to reduce the fan use to cut down on the noise.

Also keep in mind that your CoolTube will require its own intake and venting. Properly ventilated, a CoolTube will take care of most of the heat issues, so your room ventilation can even be run intermittently during the light cycle.
 
Alen

Alen

Member
i have a box 80cmx80cmx160cm....i am buying new fans and dont now what to buy...i need one input and output fan...what is the best fan for my box???
and i have a carbon filter on output fan...
Is the input fan more powerfull then the output???
 
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