Air intake / exhaust design

[gogogogogogo]

Hey guys so I'm running up against a brick wall here. Let me briefly go over my setup.

A 4x8x6 grow box custom built with two 600w cooltube lights
6" intake
2x 6" exhaust, one for tubes one for box.

A 3x3 grow tent
2x 6" exhaust up top
6" intake on bottom

Now for where I am stumped. I would like it if you could address each question individually!

Question 1: Exhaust
Now my exhaust is going to be rather complex due to size restrictions of the area I am working with. I want to know if the following method will work, or if this method will reduce the amount of air flow to an inefficient level. The three exhausts from the box and tent will be ran over drop ceiling to a basement window. There, two y connectors will be used. One a 6x6x6" Y connector, the other a 8x6x6" y connector. The 8" will be connected via a 12" to 8" duct connector to a 12x8 rectangular duct with a 12 inch round connector. Convoluted, I know. Will this work with 3 6" fans and a couple boosters or will airflow be impeded too much? If you need clarification on this, please just ask.

Question 2: Intake
Unfortunately, that is the only window in my basement. The room where this grow is located is a very dry and cool storage room. It typically sits at 58-65 degrees F and 25% humidity. At night, a 15-20 degree difference may be detrimental to my plants and I do not know if a passive intake will provide enough CO2 to my babies. On the other hand, if there were some way to get an outdoor intake, I live in Maine and winters here get bitter cold and dry so for 1/3rd of the year my intake temps will be frigid. So the question(s) is - is a passive intake of indoor air going to provide enough CO2? Should I run a humidifier? A heater at night?

Question 3: Intake Cont.
If you think I should run a duct to get fresh outdoor air, what might be the most minimally invasive way to do this? The way I see it, my only option is to cut a hole in the house and as I live in a condo this may not be a great idea.

I'm sorry guys, I know long questions like this are a pain in the ass to answer, but I'll be setting up over the next week or two and would like to get these issues panned out so I can begin my first certified legal grow. I'm so very excited to join the community of legal Maine caregivers and look forward to giving back.

Thanks guys.

 

[Roger A. Shrubber]

first off, Co2 is a moot point in a ventilated room. its entirely pointless to bother with co2 unless you have a sealed room where it wont be blown out by your fans as quick as its produced.
i'm not sure what you have for lights in the veg tent, i'm assuming one light, in the 400 to 600 watt range. with that set up, you can pull in air from the room they're in. i'd have one fan in each tent pulling through the lights, then another booster fan closer to your exhaust point. a small heater with a thermostat in the room ought to be sufficient for colder nights.
if the humidity stays under 35% or so i'd definitely get a small humidifier, again if its in the larger room where your cabinet and tent are, they ought to get enough from the room air they're pulling in.
venting is a science in itself, you have to use a reducer on smaller areas to equalize the pressure or you can collapse a smaller tent trying to get enough suction through a larger area. i honestly dont know the math, but its out there to find if you look for it, something like a room half the size of your main room will need 1/4 the airflow...

 

[HydroRed]

Question 1:
I would suggest just using one exhaust from your big grow box. What I mean is set up in this order to avoid smell leakage and get good exhaust & cool your lights all in one swoop instead of using a fan/duct for lights then another fan/duct for room air exhaust.
Carbon filter-fan-light-light-exhaust out of box.

Then you only need 2 exhaust fans/ducts total from both tent and grow box and you will be killing 3 birds with one stone, plus you keep extra $ from not buying fan/duct or the cost to run it on your electric bill every month.
As for venting the exhaust to your exit point shouldnt be too difficult since it seems like you know what you need to do. The venting can go from 6" or 8" to 12" plus if you wanted to, you just cant go the opposite like from 12" reduced down to 6" out a window. The restriction on the fan will be insane. You should be good to go the way you stated if I'm following you correctly.

Question 2:
Dont pull from outside unless you have the means & ability to flucuate with the weather and keep your room clean. Even then, I promise you it is difficult to dial in but awesome once you get it. This is how I run so I speak from actual experience, not what I read on the internet.
That being said I would suggest just pulling from the room that the tent/box are in since it is seemingly the most controlled environment you can pull from. Not to mention that would keep things so much more "simple & reliable". Those two words are always welcome in my garden. Run a heater just when it needs it like at night. I wouldnt even sweat the humidifier unless you put one in the room that the box/tent are in. I also believe once you get plants/lights etc in there they will help create better environment so humidity may not even be an issue. Air exchange will be determined by your CFM of the fan you use for the exhaust. Have a thermostat controlled plug in your tent and hook your exhaust fan to that. Set the thermostat to cool and set the temp. When the lights in the room get it up to the temp you have it set for, the exhaust kicks on and blows out the heat-pulls in cool fresh air then kicks off once temp is achieved.
http://www.westsidewholesale.com/lux-win100.html?keyword=Google_Shopping&gclid=CNbu2IHvpcwCFQepaQodRIsEtg

 

[Dogenzengi]

When it comes to air direction, I thought pulling thru a hood was best.
Pushing air into a hood will make the air work against the inside edges of the hood
At the far side before the air reaches the exit point.
IMHO
I have filter then light then fan exhausting in the same room as my tent.
The fan and filter and one 10" fan run 24/7 on one cord while my light and two 10" interior fans are on another power cord with a timer.

Bless,
DZ

 

[Roger A. Shrubber]

i too would have the fan pulling, but i would have it exhausting outside the room, inside means what odor the filter doesnt get is inside your house, as well as the heat its trying to get rid of. maybe in the winter you could exhaust it into its own room to help heat the area if necessary.

 

[gogogogogogo]

first off, Co2 is a moot point in a ventilated room. its entirely pointless to bother with co2 unless you have a sealed room where it wont be blown out by your fans as quick as its produced.
i'm not sure what you have for lights in the veg tent, i'm assuming one light, in the 400 to 600 watt range. with that set up, you can pull in air from the room they're in. i'd have one fan in each tent pulling through the lights, then another booster fan closer to your exhaust point. a small heater with a thermostat in the room ought to be sufficient for colder nights.
if the humidity stays under 35% or so i'd definitely get a small humidifier, again if its in the larger room where your cabinet and tent are, they ought to get enough from the room air they're pulling in.
venting is a science in itself, you have to use a reducer on smaller areas to equalize the pressure or you can collapse a smaller tent trying to get enough suction through a larger area. i honestly dont know the math, but its out there to find if you look for it, something like a room half the size of your main room will need 1/4 the airflow...

Yeah I definitely recognize adding CO2 to a ventilated room is a no no, in the future I hope to have more space where I can build a larger room and install a mini split system. That's a ways away, though.

I've got two boosters and three 6" fans so I think I should be covered then on the exhaust standpoint. You're certainly right though, the whole art of an indoor grow is down to science and math. Seems I'll have to break out the text books...

Question 1:
I would suggest just using one exhaust from your big grow box. What I mean is set up in this order to avoid smell leakage and get good exhaust & cool your lights all in one swoop instead of using a fan/duct for lights then another fan/duct for room air exhaust.
Carbon filter-fan-light-light-exhaust out of box.
View attachment 3664275
Then you only need 2 exhaust fans/ducts total from both tent and grow box and you will be killing 3 birds with one stone, plus you keep extra $ from not buying fan/duct or the cost to run it on your electric bill every month.
As for venting the exhaust to your exit point shouldnt be too difficult since it seems like you know what you need to do. The venting can go from 6" or 8" to 12" plus if you wanted to, you just cant go the opposite like from 12" reduced down to 6" out a window. The restriction on the fan will be insane. You should be good to go the way you stated if I'm following you correctly.

Question 2:
Dont pull from outside unless you have the means & ability to flucuate with the weather and keep your room clean. Even then, I promise you it is difficult to dial in but awesome once you get it. This is how I run so I speak from actual experience, not what I read on the internet.
That being said I would suggest just pulling from the room that the tent/box are in since it is seemingly the most controlled environment you can pull from. Not to mention that would keep things so much more "simple & reliable". Those two words are always welcome in my garden. Run a heater just when it needs it like at night. I wouldnt even sweat the humidifier unless you put one in the room that the box/tent are in. I also believe once you get plants/lights etc in there they will help create better environment so humidity may not even be an issue. Air exchange will be determined by your CFM of the fan you use for the exhaust. Have a thermostat controlled plug in your tent and hook your exhaust fan to that. Set the thermostat to cool and set the temp. When the lights in the room get it up to the temp you have it set for, the exhaust kicks on and blows out the heat-pulls in cool fresh air then kicks off once temp is achieved.
http://www.westsidewholesale.com/lux-win100.html?keyword=Google_Shopping&gclid=CNbu2IHvpcwCFQepaQodRIsEtg

Aha! That is how I ran the cool tube in my first grow. I was completely perplexed when I put the tent up today and put a cool tube in only to find, wait what, there isn't enough vents! I'm very glad you mentioned that, and I will have to think about doing just that. You are correct in your understanding of what I described, unfortunately the window is one of those sliding rectangular ones so I will have to track down a 12" to 8x12 rectangular vent pipe and the required fittings to get everything to fit.

I am curious what the average amount of CO2 in a household is compared to outside. It certainly must be lower, however to what degree I do not know. I'm looking into buying a small space heater, the room is probably only 18x12 at most. I could also just run the flower box at night and have also experimented with venting the smaller veg tent into the room itself which took temps to about 74 which is quite reasonable. As for humidity we will see, if I can just get one for the whole room that'd be great but I'd be concerned about mold.

Do you have a thermostat controlled plug you might recommend? I do not believe I will be wiring the box itself but running ext cords into it and sealing the holes with foam. This thing should be pretty damn air tight and the negative pressure will really help me out.

When it comes to air direction, I thought pulling thru a hood was best.
Pushing air into a hood will make the air work against the inside edges of the hood
At the far side before the air reaches the exit point.
IMHO
I have filter then light then fan exhausting in the same room as my tent.
The fan and filter and one 10" fan run 24/7 on one cord while my light and two 10" interior fans are on another power cord with a timer.

Bless,
DZ

I've definitely read this before. It certainly makes sense. Would you think it would be possible to have it set up filter, lights, fan, exhaust? I've got two 240 cfm duct fans and 2 440 cfm inline fans at my disposal, so I'll have to experiment with them a bit to see how much airflow I need. Messing with those damn drop ceilings is such a pain in the ass though, I hope I get it right!

i too would have the fan pulling, but i would have it exhausting outside the room, inside means what odor the filter doesnt get is inside your house, as well as the heat its trying to get rid of. maybe in the winter you could exhaust it into its own room to help heat the area if necessary.

I've definitely considered rerouting the ducting to the inside of the room and the greater basement area. My only concern here is depletion of CO2. While oil is dirt cheap right now, not having to use any to heat the basement next winter would be neat.

Thank you all for the replies and insight, it is much appreciated and you've helped me sort some of this confusion out! In the future when I rent a house boy will I have to be quite selective about potential grow areas! It's all in the space you have....

 

[Dogenzengi]

You typed "rent a house boy", lol.
I think you missed a comma.
It made me laugh
You are welcome, I am happy if I was able to help.
That why I like RIU, we help each other.
Bless,
DZ

 

[Dogenzengi]

I have a Filter then my light hood then my fan blows the air out of my tent.

I have the fan running 24/7 so I get carbon scrubbed air blowing out the top of my tent.

Drop ceiling makes it far easier, they sell the tiles at Home Depot and they are cheap.
Use a duct collar to press a circular imprint, cut out the hole and shove the collar thru so it's lip is on the side that shows.
You can even use a simple hose clamp, just tap it with a hammer to make an imprint.


I have installed a few thousand ceiling tiles in my work career.
Bless,
DZ

 

[gogogogogogo]

I have a Filter then my light hood then my fan blows the air out of my tent.

I have the fan running 24/7 so I get carbon scrubbed air blowing out the top of my tent.

Drop ceiling makes it far easier, they sell the tiles at Home Depot and they are cheap.
Use a duct collar to press a circular imprint, cut out the hole and shove the collar thru so it's lip is on the side that shows.
You can even use a simple hose clamp, just tap it with a hammer to make an imprint.


I have installed a few thousand ceiling tiles in my work career.
Bless,
DZ

Not so much that I need to make a hole in the drop ceiling, it's more rooting through pulling the duct around lights, pipes, joists, etc. all the while having my favorite fiberglass insulation and bits of the tiles falling on my face

Not my favorite process, but do it once and I'm done. I suppose if I were to run ducts in the winter to heat my basement I could leave the ones that go over the drop ceiling and use a separate duct which would probably require far less time and frustration.

 

[HydroRed]

When it comes to air direction, I thought pulling thru a hood was best.
Pushing air into a hood will make the air work against the inside edges of the hood
At the far side before the air reaches the exit point.
IMHO
I have filter then light then fan exhausting in the same room as my tent.
The fan and filter and one 10" fan run 24/7 on one cord while my light and two 10" interior fans are on another power cord with a timer.

Bless,
DZ

Keep in mind that if you run your fan after the lights, you will be pulling air through the lights *AFTER* the filter (or any other micro leaks throughout the entire system) and exhausting unfiltered weed stank air outside. Plus your fan will wear quicker since it will be hot while it is operating from being on the hot end of the exhaust after the lights. If you run the way I mentioned, you have no worries of this happening since it would just blow through the micro leaks back into the grow room instead of outside.....and your on the cool end of the lights with the fan as well. Theres no one way to do it, but just food for thought.
As for CO2, the average outside air is about 1000-1200ppm. Most CO2 runners saturate to 1500ppm avg. I did CO2 for a while and didnt really see the gains, so I quit & I save myself $25 every 2 wks on a 20# tank refill.

 

[HydroRed]

This is the digital thermostat controlled outlet I use and it works wonderful. It plugs into a regular outlet inside the box (which is where is has to be to control the temp of the box) then you plug your exhaust fan into it. Set it n forget it. Programable too if you need.

http://www.westsidewholesale.com/lu...gle_Shopping&gclid=CNbu2IHvpcwCFQepaQodRIsEtg

 

[Dogenzengi]

HydroRed I can see your logic, in my cases since I setup my tent on 3/2 all of my ducting is sound.
I have no air leaks and my grow room smells like a Doctors office even though the Moms are in the room and not in a tent with air Filtration.
If I ever take my setup apart I will do a test to see if I like your design.
Bless,
DZ

 

[HydroRed]

Just regular foil style flex tube from the hardware store without insulation they have micro pinholes in it. I have a picture of the stuff I use in the winter. Swiss cheese in comparison to the insulated I use in summer haha
Lemme see if I can dig it up.

 

[gogogogogogo]

Keep in mind that if you run your fan after the lights, you will be pulling air through the lights *AFTER* the filter (or any other micro leaks throughout the entire system) and exhausting unfiltered weed stank air outside. Plus your fan will wear quicker since it will be hot while it is operating from being on the hot end of the exhaust after the lights. If you run the way I mentioned, you have no worries of this happening since it would just blow through the micro leaks back into the grow room instead of outside.....and your on the cool end of the lights with the fan as well. Theres no one way to do it, but just food for thought.
As for CO2, the average outside air is about 1000-1200ppm. Most CO2 runners saturate to 1500ppm avg. I did CO2 for a while and didnt really see the gains, so I quit & I save myself $25 every 2 wks on a 20# tank refill.

Yeah but what is the average INSIDE air levels? It has to be less fresh, I would assume.

This is the digital thermostat controlled outlet I use and it works wonderful. It plugs into a regular outlet inside the box (which is where is has to be to control the temp of the box) then you plug your exhaust fan into it. Set it n forget it. Programable too if you need.

http://www.westsidewholesale.com/lu...gle_Shopping&gclid=CNbu2IHvpcwCFQepaQodRIsEtg

Awesome! Inexpensive and effective, I'll order one this week.

Just regular foil style flex tube from the hardware store without insulation they have micro pinholes in it. I have a picture of the stuff I use in the winter. Swiss cheese in comparison to the insulated I use in summer haha
Lemme see if I can dig it up.

What do you mean by micro pinholes? Should I invest in insulated duct or no?

 

[gogogogogogo]

This is the digital thermostat controlled outlet I use and it works wonderful. It plugs into a regular outlet inside the box (which is where is has to be to control the temp of the box) then you plug your exhaust fan into it. Set it n forget it. Programable too if you need.

http://www.westsidewholesale.com/lu...gle_Shopping&gclid=CNbu2IHvpcwCFQepaQodRIsEtg

On another note, with a passive air intake, won't smell be an issue when the fan is off during say, night?

May be possible with three ballasts in the room that cold won't even be an issue, we shall see.

 

[HydroRed]

On another note, with a passive air intake, won't smell be an issue when the fan is off during say, night?

May be possible with three ballasts in the room that cold won't even be an issue, we shall see.

The smell will only be in the box with lights off unless you have leaks in your system/box or unfiltered inlet. Like I said, you can program the thermostat controlled outlet to turn on every 15 min or whatever you program it for when your lights are off if you do happen to get worried about the smell in the box after lights go out.

 

[gogogogogogo]

The smell will only be in the box with lights off unless you have leaks in your system/box or unfiltered inlet. Like I said, you can program the thermostat controlled outlet to turn on every 15 min or whatever you program it for when your lights are off if you do happen to get worried about the smell in the box after lights go out.

What do you mean by unfiltered inlet? I was planning on just using a passive intake with a light screen to keep light out.

 

[gogogogogogo]

Hmm upon a quick look into it, I never realized how important filtering the intake was for controlling the environment. These are probably overkill, but I might look into buying a pair.

http://www.savegreenmoney.com/product-p/DS06.htm?gclid=CjwKEAjw3fG4BRDsn9GAv7T2zEkSJACNJdjg1j4i1qhJ6bLhc6lJ4bYRbRjTwnyPPxa-6sPXItwv3RoCINHw_wcB

Just not sure if they'd be compatible with my tent, the lower intake currently has a cord running through it for the light (I may try and switch this up) and the side flaps leave plenty of space for dust, mold, and insects to climb in. I may look at taping or gluing them up and run a small intake duct with a filter at the end. Not sure how this would reduce airflow, though.

 

[HydroRed]

That link you posted for the filter would work perfect for cleanliness and light. Might be able to find one cheaper though. Not sure where you live so shipping is something to be considered.

 

[bird mcbride]

In times of no practical intake filter available we've resorted to using womens stockings/pantyhose material for intake screens.