Tutorial Ventilation 101

[Nomad28743]

If you have a 9'x 9' x 8' room and exchange the air every 3 mins how can you run an AC or dehumidifier to keep up with that exchange? Especially if intake air is form outside at 80-85 degrees?

 

[Granger2]

Xanode,
Probably more likely that the tent was off-gassing something that was toxic to the plants. What brand was it? -granger

 

[Miraculous Meds]

If you have a 9'x 9' x 8' room and exchange the air every 3 mins how can you run an AC or dehumidifier to keep up with that exchange? Especially if intake air is form outside at 80-85 degrees?

That type of exchange is good for keeping temp/rh control without the use of ac/dehuey. So if u got hot temps already, n need ac, then u have to seal the grow, or exchange into a lung room, then recirculate from the lung room back to the grow. that way ur not just throwing ur ac air out the window.

 

[Miraculous Meds]

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?

What problems u would possibly have from too much exchange, would be if it makes ur rh, or temps go out of range. check out vpd, its the relationship between temp n rh. when its in the best zone ( about 10% less rh than ur temp), ur plants breath easily, n transpire water at the best rate for explosive growth. with that good of exchange, odds are u prob might be too low of a rh, causing the plants to keep losing water at a faster rate than they can replace it, so u get nutrient build ups n leaf burns, and deficiencies because the plant cant get the nutrient to the needed tissue before the water is sucked out by the low rh environment.

Figure out ur cfm, 2 times a minute is suggested by a lot of pros. its best for keeping temps without ac if ur outside environment is cool enough. but it also brings in enough fresh co2 to keep ur plants fully rocking.

Odor control. neg pressure is always best, so a speed controller to keep the exhaust/carbon filter running is important. also u could scrub the air by just circulating a carbon filter in the room. not as effective, but will do the job pretty well if ur room is decently sealed, and there is no positive pressure. or like I do is exhaust with a carbon filter, then if exhaust is not needed, or like now im using ac, I circulate carbon filters between my veg n flower, so there is a constant carbon filter running at all times.

 

[Nomad28743]

Miraculous Meds:
First off TY for your reply.

If there is no lung room available and then going sealed room where does the necessary air exchange happen? That hurdle sounds equipment intensive.

Do people just pay the AC bill or must they grow in the Spring and Fall with the summer times out?

 

[Granger2]

Nomad,
In a properly sealed room with AC, Dehum, CO2, no air exchange is necessary. Good luck. -granger

 

[Nomad28743]

The no new air is replaced by the CO2. I get it.

 

[Miraculous Meds]

Miraculous Meds:
First off TY for your reply.

If there is no lung room available and then going sealed room where does the necessary air exchange happen? That hurdle sounds equipment intensive.

Do people just pay the AC bill or must they grow in the Spring and Fall with the summer times out?

Going sealed u have to keep the environment in check with ac/dehuey, whatever's needed to stay in the parameters. With no exchange, u just circulate air around the grow with fans blowing in all directions. Gentle on the leafs though. Then u need a carbon filter n fan scrubbing the room.

Ur choice, pay the ac bill, or don't grow, when u have to use it. People do both. some grow out doors during the hot times, n inside when its cool.

 

[Nomad28743]

Sorry for the additional question but why is a carbon filter needed to scrub the room?

 

[Jhhnn]

Sorry for the additional question but why is a carbon filter needed to scrub the room?

Because otherwise you'll reek out the house when you open the door. Low power fans can be used because the air gets scrubbed continuously, over & over again.

 

[Nomad28743]

What scrubber system would work on a room 9 x 9 x 7?
Any guess on the eq cost?

 

[Granger2]

9x9x7=567 cu.ft. To scrub all the room air once per minute you'd need the following. More is better. Here's a deluxe set up.
http://www.greners.com/i/fans-ventilation-filters/products/brand/vortex/vortex-s-line.html 8"
http://www.greners.com/i/fans-ventilation-filters/filters-odor/brand/phresh/phresh-filters.html 8"
Shop prices. Good luck. -granger

 

[mojave green]

Nice one granger, appears that you can power it with either 120 or 240!

 

[Nomad28743]

TY Granger

 

[Nomad28743]

I cannot believe the difference in noise a funnel makes!!! I saw those diagrams with the open fan, 90 degree flange and the funnel/bell shaped intake and thought yeah that makes sense for air flow but boy when I placed the pet cone from my rat terrier over the intake on my duct fan I use to push air into my place I was amazed at the DB reduction!!!!
It reduced the noise from a hum I had to hear to NO hum at all. I now have to check and see if the darn thing in running!
Anyone else got results like this?

 

[r2k]

I cannot believe the difference in noise a funnel makes!!! I saw those diagrams with the open fan, 90 degree flange and the funnel/bell shaped intake and thought yeah that makes sense for air flow but boy when I placed the pet cone from my rat terrier over the intake on my duct fan I use to push air into my place I was amazed at the DB reduction!!!!
It reduced the noise from a hum I had to hear to NO hum at all. I now have to check and see if the darn thing in running!
Anyone else got results like this?

Props for the clever approach. I have only seen people throw their cone of shame away when their pet has recovered. Very creative.

I bet you get more airflow through that same fan with the cone. I know the main noise disappeared, but I suspect you may also notice a change in the overall fan pitch. I think the pitch will drop because the fan is able to pull air easier. Listen to your fan, it will tell you when it is working harder because the pitch goes up when it struggles. The pitch goes down when moving air is more efficient.

Let me know if I guessed correctly.

-r2k

 

[Nomad28743]

r2k
You are right on the money... the fan pitch went down and I believe he fan has to work less hard which I hope will extend the fan's useful life.

 

[Stoner10000]

Is it worth it to read past the first pages?

 

[DoubleTripleOG]

Is it worth it to read past the first pages?

Yes, it's useful to read past the first few pages. Just get really high first and get in the "zone".

Sometimes the most useful reply or answer your looking for pops right out of the middle of nowhere, in seemingly boring posts. Either that or down the road something you read is gonna help you.

 

[Nomad28743]

DT OG,
Man you hit on the head. I waded thru the many pages looking, reading, reading twice sometimes a third time and then it hit me (your down the road comment) BOOM the light came on.
For some of us older folks it takes even a while longer than for you tech savy whipper snappers.