Tutorial Ventilation 101

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[Granger2]

Can you send a link to the fans your talking about? -granger

 

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[messn'n'gommin']

I'm helping a friend set up a small personal cabinet medical grow, and this thread has convinced us to go with dual stage cooling. It's a 400W CMH in a 27" x 27" space - Would 2x ~100CFM S&P inlines (one for air cooled hood, one for a CAN 2600/9000 carbon filter) do the trick? Stealth is key so she wants something that is incredibly quiet, but we also want to make sure it's up to the job. Thanks!

Don't mean to get off topic, but what I bolded in your quote, is what got my attention.

One fan is going to make noise, so two fans will make more. There are a couple of things you can do to reduce the sound level (Like using the S&P's for one), but making them quieter is a bit different making them quiet. There are some things to reduce decibels, like adding a muffler (at a slight cost to resistance); insulated vent tubing (at a slight cost of space); cushioning any contact between the fan and whatever will transmit sound; a smaller light (250w is just about perfect for that size footprint...meaning a lower power fan); masking (a fish tank is an alternative answer to the eventual question, "What's that noise?");

Or, speaking of masking, a lockable upright freezer answers the question before it's even asked:

[FONT=Arial, Helvetica, sans-serif]“Destroyer on Ice – 250CMH Freezer Grow,” by FreezerBoy
https://www.icmag.com/ic/showthread.php?t=99905[/FONT]

Also, CFL's, T-5's, and LED's would be somewhat easier to cool with lower powered fans (meaning reduced noise) than an HID.

Sadly, however you choose to do it, it's going to make noise to some extent.

 

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[mliokv48]

I am in a 5x5 tent. I am shooting for 1500 Watts. 300 Watts plasma and will be a/c. 2x600 Watts open bulb. 8' ceiling. I have 950 cfm exhaust. Idea is to maintain low air exchange per minute and still be able to exhaust the heat. With this intense of light what air exchange per minute should I look to achieve for the plants at 50% Rh. I will duct rest of the necessary air (to defeat heat) into tent above canopy to evacuate heat via another fan/duct. Lower intake fan will be ducted around tent. Ducting will be closed on the end. Poking holes all around ducting to shoot air into corners, walls and canopy. Does this sound feasible? I have already got the gear. Basically 950cfm filter. 1x 10" fan & 2x 8" fans 1x 6"fan. Fans are hyperfans, speed controllable and pull very little juice.

 

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[mliokv48]

What is your room size and setup? what you trying to accomplish with this?

 

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[mliokv48]

Cfm after ducting and filter.

 

[ARTofMAKINGfire]

http://www.testequipmentdepot.com/fieldpiece/anemometers/sta2.htm

 

[Kyriakos]

Hello fellas,

In a room that is 3,5m x 3,3m x 2,9m I have decided to use an extractor fan that will be around 2000 m3/h. I will also use a carbon filter to this. This area will have nine 600w HPS lamps. Can someone help me out on chosing the right size for an intake fan in m3/h or explain to me the right way to calculate it myself?

 

[Four20omky]

how can i get more humidity..?

how can i get more humidity..?

Here is a picture of my Grow Box at the moment. (just the veg box)

1x 600w HPS in Vented Hood*ultrasun; I have a Ushio on the way, but.. mail..

1x 400cfm 6in duct fan.

8x t5 6500k bulbs in the back

1xHumidifier - 1 setting.. on

2x 6in clip fans - 2 settings low/high

1x 16in Oscillating Fan - 3 settings .. 1,2,3.

I've got one 6in fan stuck in>> the 8 in hole behind the clone box and one on the 8 in top vent out>>.

The hood is 6 in, with glass. Vented at 40cfm, its about 13-16 inches from plant tips with 91. under the bulb, i'm running 35%-ish humidity;

The problem is that i want 70% Humidity.. cuz.. thats best? right?

But i can't manage to get there.

If there is a way i can rearrange my tent to make this happen; or.. maybe a quick "buy" that i can pick up.. anything to get this optimal..
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Thanks.

-Stephen-

 

[Four20omky]

the tents are 4x4.

 

[kollos]

Hello guys,

Im kinda unsure if this is the right equipment to buy,

Im having a 6" passive inlet and a 4" active outlet in my room.
The exhaust fan is on 24/7 all year everyday never off.

BUT IF THE ELECTRIC GOES OUT, or THE FAN DIES,

The smell goes right out the passive intake
Would a backdraft damper work perfect to fix my problem? would the backdraft damper be open 24/7 when the fan work and when the fan die it closes the inlet to 100% ?

Would a 220cfm fan have enought negative pressure to open a 6" passive backdraft damper?

Thanks alot guys!

 

[Kozmo]

Would anyone be willing to talk about Air exchange rates for a LED's. how necessary is it. Lets say 3-4 exchanges per hour...

 

[Jibman]

Trying to decide between a 6 inch Elicent or Vortex?

Would the 6 inch Elicent be ok for two 600 watt air cooled lights?

 

[medicalmj]

Trying to decide between a 6 inch Elicent or Vortex?

Would the 6 inch Elicent be ok for two 600 watt air cooled lights?

Get an 8" fan. The price diff b/w a 8 and 6 is (should be) very small. In theory yeah, should be fine but most hoods leak and u can always get a speedster and turn it down.

 

[Kozmo]

Never got any bites on the above question. But this is where I'm at. Air exchange between 6-8.5 cfm. Constant negative pressure of .001. My buds are coming along nicely.

 

[Xanode]

I have a question about the original post:


The first few example diagrams showing basic growbox layouts are actually saying that its fairly easy to over ventilate a box and put stress on the plants? Am i understanding that correctly?

So to have 24/7 odour control you would need a fan speed controller to slow the fan, so its constantly scrubbing exhaust but at the same time not too strong that it stresses the plants?

Awhile back when i had a small tent grow, i was having nothing but sick plants no matter what i changed, but i never thought it could have been that my fan may have been to strong for the tent size and making the plants weak and sick. I had an in line fan running at 100% 24/7, im not sure of what its CFM was as i don't have it any more but it was quite strong. Could of over ventilating my tent have been the problem all along?