To start off, I first grew in a computer using a 70w hps and then in my current 150w hps cab. Ever since I've been growing I have been thinking of different and better ventilation options. I have designed somewhere around 10 different setups trying to incorporate carbon and a small Lasko squirrel cage fan. Some worked and some didn't.
My last design was to have the fan inside the box sucking through a cool tube and then pushing it outside the box in a 4" line and then into a 6" x 16" custom carbon scrubber. It was my best design for airflow and smell removal. The problem was too much restriction. The air was restricted in the following: 4" cooltube, bend in airflow from the exhaust to 90 degrees left into the exhaust line, and the biggest was pushing the air through a scrubber.
Fans are much more efficient at sucking through restrictions than blowing through them.
The other major flaw was that my intake was on the floor, and my carbon scrubber was also sitting on the floor. Some exhaust was getting in my intake even though I had sectioned off my closet to try and make a path of cool air to the intake. The only way to fix this is to intake at the floor and exhaust at the top up and away from the intake.
My other huge requirement is silent. I'm not talking about quiet so you don't hear it when the door is closed. I live with roomates that don't know I grow and I need to keep it that way. The closet can't make any noises.
The new design basically uses a horizontal screen to hold a bed of carbon. I have a little less surface area to diffuse the air through vs my 6" scrubber (240in squared vs 301in squared) but that doesn't seem to be a problem. Just above this I have my lasko fan on low hanging by rubber bands with a 1" foam tunnel on the exhaust to muffle the noise.
On low it is silent. All I can hear are the other fans on for circulation. On high it can be heard, but I haven't insulated the inside with foam as I've done before. The temps seem to be hovering 3F above ambient and I haven't hooked up the fan yet to blow across the bulb. As for the smell, I can only imagine that it will be removed as I used all the carbon from the scrubber and put it in my new setup.
The only thing I might do differently is to add a few more supports holding the screen up. In fact, I still might do this.
Enough! How about some pictures?
The old:
The new:
Screen:
Starting to add the carbon...
Almost done. Just need the last piece or cardboard to make the fan suck through the carbon.
Done.
Here is a picture of the back of the cab. The thing sticking out on top is the exhaust that is connected to the fan. I then put more foam curving up to make all the hot air go up the wall vs down and into the intake. It probably helps with sound too.
My last design was to have the fan inside the box sucking through a cool tube and then pushing it outside the box in a 4" line and then into a 6" x 16" custom carbon scrubber. It was my best design for airflow and smell removal. The problem was too much restriction. The air was restricted in the following: 4" cooltube, bend in airflow from the exhaust to 90 degrees left into the exhaust line, and the biggest was pushing the air through a scrubber.
Fans are much more efficient at sucking through restrictions than blowing through them.
The other major flaw was that my intake was on the floor, and my carbon scrubber was also sitting on the floor. Some exhaust was getting in my intake even though I had sectioned off my closet to try and make a path of cool air to the intake. The only way to fix this is to intake at the floor and exhaust at the top up and away from the intake.
My other huge requirement is silent. I'm not talking about quiet so you don't hear it when the door is closed. I live with roomates that don't know I grow and I need to keep it that way. The closet can't make any noises.
The new design basically uses a horizontal screen to hold a bed of carbon. I have a little less surface area to diffuse the air through vs my 6" scrubber (240in squared vs 301in squared) but that doesn't seem to be a problem. Just above this I have my lasko fan on low hanging by rubber bands with a 1" foam tunnel on the exhaust to muffle the noise.
On low it is silent. All I can hear are the other fans on for circulation. On high it can be heard, but I haven't insulated the inside with foam as I've done before. The temps seem to be hovering 3F above ambient and I haven't hooked up the fan yet to blow across the bulb. As for the smell, I can only imagine that it will be removed as I used all the carbon from the scrubber and put it in my new setup.
The only thing I might do differently is to add a few more supports holding the screen up. In fact, I still might do this.
Enough! How about some pictures?
The old:
The new:
Screen:
Starting to add the carbon...
Almost done. Just need the last piece or cardboard to make the fan suck through the carbon.
Done.
Here is a picture of the back of the cab. The thing sticking out on top is the exhaust that is connected to the fan. I then put more foam curving up to make all the hot air go up the wall vs down and into the intake. It probably helps with sound too.
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