Please help with Air movement!

[420truckin]

hey everyone, Im getting pretty close to having my cabinet done, also am a first timer. Ive been doing alot of reading and research however have not really found a SOLID answer to my question. My cabinet IDs are as follows - 23" D x 54" H x 60" W. I just ordered a quantum badboy t5 4 foot 6 light fixture, and ive also got 4 fixtures mounted in the cabinet that will have y splitters and 2 cfls per fixture. The inlet of the cabinet is down low on the right side, and the outlet is at the top on the left side, however the outlet ive got 2 activated carbon filters connected to elbows, that are connected to a "T" fitting that runs to the outside of the cabinet, and i was planning on using a inline fan for sucking the air through the carbon filters. However I was also planning on using the same inline fan for the inlet as well. My question is, will that be too much airflow going into the cabinet? The inlines im looking at are 165 CFM per unit. Would i be better off using a duct booster inline, and use the regular 4" inline for the outlet?

 

[Muttt]

Re: Please help with Air movement!!!

When I built my cabinet, I drilled holes along the bottom and put the fan and carbon filter up top. That way, it draws cool air in through the bottom since the cabinet is negatively pressurized. Draws the hot air out through the carbon filter at the top of the box. 165 should be fine. You can always put a dimmer switch on it to slow it down.

 

[420truckin]

Re: Please help with Air movement!!!

This is the cab this morning before i got the doors on, i still need to paint the inside of the doors, but anyways here is a pic of the cabinet, you can kind of see where the inlet is, and you can see where ive got the carbon filters at. I would like to keep as much space in the cab as possible so thats why instead or running oscillating fans inside, i figured i could just run a lower cfm inlet fan but i dont know if 165 is too much air going in, thats my biggest question i guess, the inline duct booster is 70 cfm, which i will make a filter for it just dont know if 70 cfm is too much going in.. just dont want tons of pressure in the cab because its pretty sealed up. No light coming through the doors right now with just the 4 soft white cfls in it, but after i get the doors painted i will put the door seals in and make sure its sealed even better.

 

[Muttt]

If you use a fan pushing air into your cabinet, what's you are going to do is pressurize your cabinet. So, any tiny little opening will allow air and more importantly (that depends) SMELL to leak out everywhere. But, if you only have vents for letting air in and you push or suck the air out of your cabinet, then you end up turning your cabinet into a vacuum. You end up sucking air into your cabinet and it is then sucked through your carbon filter as it exits through the fan.

 

[420truckin]

So even if i use a higher CFM exhaust fan, you think it will still pressurize the cabinet too much? Like i said a 70cfm intake and 160-200 exhaust?

 

[oldhippie64]

420truckin lets say you cab is airtight or close if you use a higher CFM exhuast fan then intake fan the exhaust is trying to pull 160-200 CFM's thru a intake only allowing 70 this will create negative pressure so all air goes thru filter but you are trying to pull 160-200 CFMs thru something that only going to want 70CFM thru it. the fans wont like that, one fan will try to speed the other up and the other fan is going to try and slow the other down. I don't see anything gained by trying to use both intake and exhaust fans air going thru cant go any faster then the fan with most CFMs.

 

[Muttt]

I think just using an exhaust fan ..... and just leaving an opening or vent to let air get sucked into the box will work just fine. My box is 3' x 4' x 6' tall and that's how mine works. It moves so much air, I have trouble keeping it at 74 degrees in there.

 

[420truckin]

Thank you OH64, Now i understand where you are coming from. I will just put a filter on the intake and maybe put a small oscillating fan inside. Thank you mutt as well for all your help and info! Havent been here too long and i can already see this is the best place to be. So many great knowledgeable people! Again thanks guys!!

 

[sfttailpaul]

hey everyone, Im getting pretty close to having my cabinet done, also am a first timer. Ive been doing alot of reading and research however have not really found a SOLID answer to my question. My cabinet IDs are as follows - 23" D x 54" H x 60" W. I just ordered a quantum badboy t5 4 foot 6 light fixture, and ive also got 4 fixtures mounted in the cabinet that will have y splitters and 2 cfls per fixture. The inlet of the cabinet is down low on the right side, and the outlet is at the top on the left side, however the outlet ive got 2 activated carbon filters connected to elbows, that are connected to a "T" fitting that runs to the outside of the cabinet, and i was planning on using a inline fan for sucking the air through the carbon filters. However I was also planning on using the same inline fan for the inlet as well. My question is, will that be too much airflow going into the cabinet? The inlines im looking at are 165 CFM per unit. Would i be better off using a duct booster inline, and use the regular 4" inline for the outlet?

Your cabinet being: 4.5' X 5.0' X 2.0' = 45 cu. ft. If you use the same in-line fans and run them ON together, you'll be moving 660 CFM's, not 165cfm IN negated by 165cfm OUT. When in piggy-back, the CFM's are quadrupled. IMHO, that'd be too much wasted air movement although dust would never settle... That's exchanging the air 14.666 X/minute! Like every 4 seconds a complete replacement of the air! They say, exchange 2-4 X/minute is fine, a bit more for stalk/branch strength and even 5-6X exchange would be on the high end. This is what I have learned... I like the design MUTT did and the higher the movement the nicer this would work, swirling the air up from the cold source, not to mention the replenishment of natural CO2. I have a flower room that is 4,250 cu. ft. with two identical attic ventilation fans, the small gable-end version {14" dia.}, that runs at 150 CFM each. My room's complete air exchange a bit north of every six minutes, this using two fans that cost under $75.00 each and found everywhere. I keep the temps around 85* with lights on (8 X 600W) but have plenty CO2. Please, remember that this is JMHO based on life lessons...

 

[420truckin]

Your cabinet being: 4.5' X 5.0' X 2.0' = 45 cu. ft. If you use the same in-line fans and run them ON together, you'll be moving 660 CFM's, not 165cfm IN negated by 165cfm OUT. When in piggy-back, the CFM's are quadrupled. IMHO, that'd be too much wasted air movement although dust would never settle... That's exchanging the air 14.666 X/minute! Like every 4 seconds a complete replacement of the air! They say, exchange 2-4 X/minute is fine, a bit more for stalk/branch strength and even 5-6X exchange would be on the high end. This is what I have learned... I like the design MUTT did and the higher the movement the nicer this would work, swirling the air up from the cold source, not to mention the replenishment of natural CO2. I have a flower room that is 4,250 cu. ft. with two identical attic ventilation fans, the small gable-end version {14" dia.}, that runs at 150 CFM each. My room's complete air exchange a bit north of every six minutes, this using two fans that cost under $75.00 each and found everywhere. I keep the temps around 85* with lights on (8 X 600W) but have plenty CO2. Please, remember that this is JMHO based on life lessons...

So in other words i would be fine just leaving the inlet open or filtered, and JUST running the 165-200 cfm for the exhaust through the carbon filters?

 

[sfttailpaul]

so in other words i would be fine just leaving the inlet open or filtered, and just running the 165-200 cfm for the exhaust through the carbon filters?

absol-ute-ly! And that will give you 3-4 complete air exchanges per minute...

 

[oldhippie64]

if you have fan on timer I"d filter both exhaust and inlet so air/odor cant back flow out when fans off. if the fans on 24-7 it cant so it wont matter

 

[420truckin]

What i actually have for the "inlet" is a regular house vent register, like what is in the floor. and the tube comes out the front of the cab instead of just out from the side. Ill get a pic later, however all i was going to do was make a little box with a filter and put that inline fan in there, however i wont be using a fan there now. One thing ive noticed though is now whenever i have the lights off it was getting about 50 or so in there, i noticed it before i put seedlings into it, so i have a small thermostatic heater in there set at 70-75*. I will have to do something about that when i get my inline fan, because its been getting down to about 42* during the night. Could i maybe setup a heater in a box like i planned on doing with the filter and what not and just put the heater in the box connected to the intake of the box? I ordered the inline fan for the exhaust yesterday so ill hopefully have that soon, although as of now itll be a reggies bagseed grow, considering first time n all. I probably dont "need" it RIGHT now but i want it for when i do. also i will just get a small 4" or so oscillating fan and put that inside for strengthening stems.. Does this sound like a good plan? Maybe give some ideas as of how i could do it differently or anything?

 

[oldhippie64]

Hmmm if you need heat. you'll want to control exhaust fan I don't know about tieing the heat to air intake all depends on how cold things get personally I'd keep it separate allowing heat to recirculate air inside.

 

[420truckin]

I dont have an exhaust fan yet, i did order it on friday, but have 8 germd seeds, one above soil right now i just have a little heater inside of the cabinet with the thermostat set at 75 degrees. It honestly only runs when the lights are off, and when the lights are on it never goes above 80 degrees.. Its been hitting freezing temps outside, i need to get one of those RH, and temp gauge things, but i havent been able to find them anywhere where i live.. Any place in particular you can get them? Also have a small 4" oscillating fan inside the cabinet to move the air around a little bit. Right now there is 4 23 watt 2700K cfls in it, as well as 4 40 watt T8, 6700K bulbs about an inch above the pots.. Really thinking of making a smaller cabinet for veg growth, maybe after the T5 fixture and inline fan get here i can maybe work on that and then just move the 4 fluoro tubes into the smaller cabinet.. Not sure why or how but the one that sprouted was above ground after one day of being in there. all the other ones havent shown yet.. been on 12/12 since i put them in there.

 

[oldhippie64]

you mean something like the Dayton 10N203 Attic Fan Thermostat/Humidistat. grainger.com has them, Lowes or Home Depot should too.I'm not sure how others have controlled exhuast fans but I recall seeing a timer used. this seems logical since part of the ventilaations function is to give plants fresh CO2. not sure whats best.

 

[sfttailpaul]

you mean something like the Dayton 10N203 Attic Fan Thermostat/Humidistat. grainger.com has them, Lowes or Home Depot should too.I'm not sure how others have controlled exhuast fans but I recall seeing a timer used. this seems logical since part of the ventilaations function is to give plants fresh CO2. not sure whats best.

I wouldn't buy things from Grainger; most expensive place there is (Like Macy's for underwear). Try Amazon. You can get a combo Temp/Humidity control (hat's what I used/bought there) for like $30.00 there. Just do a search for it and they'll pop up. Surprising what Amazon has, like feeBay or even better!
I also wouldn't put a heat source in-line with your air flow system because it'll get cooled down just in the transfer. You can get a small heater unit (like 5" cubed) for around another $30.00 that will give you the temps by itself. The best way to control all this stuff is with an "atmospheric controller" but these cost big bucks (mine was $350.00 +/-) but they are extremely accurate, give you the means to have night only circuits, control circ fans as well as CO2 and on & on... I think worth it for a medium sized rower, but way overboard for a small grow, like <20 plants? IDK, just my 2cents...

 

[420truckin]

So as of right now, i had 8 reggies seeds, only one had a healthy start and sprout all the other ones never did come up and after moving some soil noticed that the seeds had small taproot but they were like that when i planted them. So now ive got one healthy one. Ive got the heater in the cabinet set at 75 degrees, and ive got a little oscillating fan, and i started putting 2 1L glass mason jars in the cab full of ice cubes, and since ive done this its raised the humidity in the cab from around 20 to 48.. So i think thats a good start. im still waiting on my inline fan, and all i need maybe for that is like you guys said is a thermostat controller, which i have pretty much saw that at most hydro stores. When the lights are on the heater never runs, but the temps hit about 83 while the lights are on. lights off it goes down to about 73 ish.. Heater inside, fan inside and just a small filter on the inlet of the cabinet so no dust or insects go into it. I think i am going to order a few autoflower seeds, just to test my luck and see how it goes, after the inline gets here... I really only need that and my light fixture to be 100% done.. For time being ive got 4 6500K 40W T8 Tubes and 4 soft white cfls.. Hopefully should have the light fixture and inline fan by beginning of next week. Not that i really need the inline, yet but would be nice to have.