room re-design...need airflow help

[greentrich]

OK...so I'm completely re-vamping my room, specifically the hood, fan, filter combos and wanted some advice from some seasoned growers here.

First I'll start with two examples I have.

For example "A", this seems a more effective way to cool my tent and hood. However, the caveat here is the hood cooling completely bypasses the filter, so if there is even one small leak in this...I'm hosed. Not to mention the cost of buying two active exhaust systems. Now I have an after thought that I didn't include in example"A", that is to duct the intake of the hood to the a/c unit...just to ensure coolness.

Example "B", this looks a little safer as far as odor control and of course cuts costs in half. On this one though, it doesn't seem like it cools the hood nearly as well as the previous example.

So...which one is better?? My room has an in wall a/c unit so the air the passive intakes pull in would be cooler. I have done searches here on ICM and found a few threads, but none that answer my questions...really good info though.

Something that could change all this: These examples are dependent on the filter of choice being a pull only filter i.e. a Can filter. I have not purchased anything yet, so if someone suggests a push filter, then that would require another design...which I'm not opposed to. I just have notice pull filters being the norm around here.

Ultimately what I would like to accomplish is to have the a/c ducted directly into the hood (as opposed to ducting the a/c into the tent, then relying on the tent air/temp to suck through the filter>hood>exhaust...trying to cool the hood) while still using a filter and one exhaust. There are many ways to accomplish this and was wondering if anyone had any insight on the best way.

Sorry if this is confusing, but I've been racking my brain for the past couple hours on this and am spinning.
Thanks for any help!

 

[ilovethewest]

almost there man. try what i do. carbon filter->fan->duct->hood->duct->hood->duct->muffler->exit
one bit of advice i learned on here 6 months ago is that when your installing or thinking about where to place an inline fan, put it before the heat source. think of what a few years of heat going through it will do to the parts. and i have been told that inline fans work better pushing and not pulling, although they can do both. give me some rep i you like that.

 

[Tropic]

give me some rep i you like that.

WTF? Asking for rep is lame...

 

[greentrich]

Thanks ilovethewest...actually something I haven't thought of. I had been fixated on pulling the air through the hood, not pushing it. Plus with positive pressure going from the fan, through the hood, and ultimately out the tent...if there does happen to be a leak it wouldn't matter.
Thanks for the thought, I'll look into that!

 

[whodat nation]

I agree with Ilovethewest- I have used that kind of set-up before and it can work. Just make sure to compensate for the extra cfm needed to do both jobs and maybe add a small booster fan at the outtake of the hood or at the exhaust of the tent...or both. (THIS WAY YOU CAN STILL SUCK AIR OUT). Also if you are so concerned about “leaks” smell- you should up the cfm of the entire system seeing that it not only needs to cool the hood and filter any smell but also create enough negative pressure to ensure this all works.
Additional cfm will be needed with increase of bends and length of ducting. Make sure the fan fits the rating of the filter, you might already know this but it doesn’t hurt to say.

 

[ilovethewest]

im glad it helped. also 3x the size of your ducting is needed for the passive air intakes.

 

[Lorenzo]

why is the lifespan of the fan such a big priority?

priority #1(a/b) is temp/airflow
priority #2 is odor control

your example A is the most efficient. if you're real worried about odor, seal the hood/duct connections with aluminum (heat resistant) tape.

 

[Peanut Butter]

Use A if you are at all concerned about temps, but put light-fan before the hood

You want to push through the hood in case there is any leaks. Air will be pushed out of the hood into the tent....meaning no smell should be able to escape through the light cooling route. Still try to seal it up best you can, the less warm air escaping into the room the better. Depending on you lighting, length of ducting, and how directly you pull air off the AC, you may be able to get away with a duct booster fan or a stanley blower to cool the light.

BTW, using fans to pull air through resistance is always more effective that trying to push through resistance. Pushing through the light is just better in this case since we are avoiding negative pressure.

 

[SKUNK420]

Check this out re-did your example "b". If you set it up like this with the FILTER > FAN > HOOD > OUTSIDE you will be able to get your air filtered, humidity sucked out the room and light cooled. The fan is placed between the filter and hood so you will be #1 blowing air directly on the bulb which will keep it really cool and #2 you are pushing air so any leaks they will blow back into the tent. Yes you will be sucking air through the filter and could sucking smell through ducting connections but not really if you just tape up your ducting properly. There are only 3 connections from fan to filter: fan > ducting > flange > filter.

 

[!!!]

Remember that most filters are not inline (those exist however.) so you will have to place it at the end of your air flow setup rather than in between (as per your example "B")

See SKUNK420's example "B" (post #9) - this is a common setup.

 

[Buzzsmirk!]

i would set it uplike ex "A" except use co2 burner and dont vent ur passive air in/out and use the A/C to better advantage in the grow space

use the scrubber to scrub and recirc the air within the space NOT to suck ur valuble A/C out!!!!

seal that bitch, vent ur light w/ outside air and exhuast ur hotairbackout w/glass sealed hood, use the scrubber to "scrub" and keep the scrubbed air withiin the space.
use CO2 system and move the A/C in the grow space itself then vent/change the air in the room to deal with the a/c heat (more stealthy than a/c in window too.)

do not set up a config that sucks ur a/c air ($$$$) outa the grow space!!!

hope this helps and not lookin for a "debate" either just consider my reasoning and apply if it suits ya

BUZZ!

 

[greentrich]

Awesome...great responses everyone! A lot of really good ideas here...so I have a lot to consider.

your example A is the most efficient. i

Use A if you are at all concerned about temps, but put light-fan before the hood

Thanks for the thoughts! I though A would be the most effective, but it is more expensive. Don't really know if I have a budget here..depends on a few things, but I like A for cooling purposes better.

Check this out re-did your example "b". If you set it up like this with the FILTER > FAN > HOOD > OUTSIDE

Thinking I'm diggin' this one the most. Less monies to spend and seems efficient.
Question....will having the fan blowing on the bulb after sucking in the tent air really cool that much more?? I have never had a sealed hood so I honestly don't know what to expect as far as how well they cool, which I imagine is dependent on the setup.
Yes...this is my first air cooled hood...."I'm all growd up Ma!"

Remember that most filters are not inline (those exist however.) so you will have to place it at the end of your air flow setup rather than in between (as per your example "B")

Shit I didn't catch that! See...that's why I'm here. I know they make inline filters, but I can't say I'm sold on them. I guess merely for the fact that in any pics,,,,I haven't seen a single one. I don't know anyone that uses inline filters. Has to be a reason right??

use the scrubber to scrub and recirc the air within the space NOT to suck ur valuble A/C out!!!!

Now this one rocks...I was always bothered when I had my setup sucking all the cool air out. I like this one, but again...I'll have to see how the funds go. Summer sucks here.

use CO2 system and move the A/C in the grow space itself then vent/change the air in the room to deal with the a/c heat (more stealthy than a/c in window too.)

Now I KNOW i won't be able to afford a c02 system. Moving the a/c isn't an option either unfortunately. It's a tent within a room, and this unit is big and heavy. I know what you're saying about the a/c being suspect, but it's been in the wall (not a window if that matters???) since day one from the previous owners, and somewhat concealed, so I'm not too concerned. The idea is appreciated though.

do not set up a config that sucks ur a/c air ($$$$) outa the grow space!!!

hope this helps and not lookin for a "debate" either just consider my reasoning and apply if it suits ya

Love that idea...have to work something out on that one...somehow.

Of course it helps Buzzsmirk! Won't find a debate from me. Everything here helps and is more informative than I thought it would be. I hate it when a question is asked and no one replies LOL, so I really appreciate everyone's input...I like ideas.

I read both threads on ventilation in their entirety...so I have the pressure principles down. Just need to hammer out what will work best for me.
Any more ideas...let me know! I'm gonna go re-design some shit now dammit!

GT

 

[greentrich]

New Design:

New Design:

Ok Buzzsmirk, I took your idea and ran with it. Mainly cuz I liked the idea of keeping the incoming cold air in there.

My reason for this design is it incorporates a couple parts I already have: The Dayton blower, and the 4" inline canfan. Only thing to purchase then is the 6" ducting, the MountainAir filter, and the 6" inline canfan. Oh..and of course the hood.

So this is a modified example of "A", which I really like: Vents the hood with a/c w/out risk of smelly leaks. It also keeps in cooler air brought in by the filter/fan, and the active 4" intake. Plus it will have a passive intake...if needed, which leads me to my next question:

With a 140cfm blower NOT exhausting out of the tent and keeping it inside, will there be enough negative pressure in the tent that is 56 cubic feet?

Also, is the heat venting into the attic ok for security?? I was concerned about flir picking it up, but I guess if they are flir'ing me I'm already fucked.

Lat question...is the 210cfm filter a good combo with a 140 cfm blower? I thought I remember the rule of thumb was that your filter cfm had to be larger than your fan cfm.

Thanks for looking and ANY contributions made!

 

[ilovethewest]

if your trying to throw the filter and light cooling no different systems, i see a much more efficient way to amend your current drawing. i would not worry at all about having your air con cooled air go through the hood. i would definitely have the fan before the hood for positive pressure in that system. but i would get that air from out side, put it through a simple dust filter, through air cooled hood, and into attic, or out side. make a muffler for the end of the system if its loud, and a box with foam around the fan. the air from out side should be able to hold enough of the heat if there is enough air flow. and this way you could vent the air con into the tent, eliminating all the radiant heat, or directly cooling your plants.

 

[greentrich]

Good idea West.
However, where I am located...the outside air is a no no. It's hotter out there than in my tent. During the fall/winter though, that's exactly what I plan to do.

The a/c has two vents, so as of now...I plan on venting one into the hood, and one into the tent. When it starts to cool off here, then I will switch the duct to bring in outside air probably with a cone HEPA filter or something. As of now I'm not growing, taking the hottest part of the summer off. I will start again when the temps start to drop, which is why I'm researching this (among other things) now, so when I start I can just go ballz deep and not have to design on the fly.
So, when it starts to cool off and I can intake outside air, I plan on having an 8" inlet that goes to a Y...one 6" and one 4". The 6 will go to the hood, and the 4 will go to the tent.
Sound good to you???
Also, is there a security concern with venting the hot hood air to the attic? The room itself is about 20'x15' with a high pitch roof, although the ceiling is flat. So it's not a huge attic, but it's decent sized and very well insulated. I'm just concerned about the hot air coming out of the attic vents.
Thanks again!

 

[rocket high]

hi greentrich ... ive got that same problem about venting into the attic ....it will glow like a candle on the flir which is a right pain... my attic is kinda big but not well insulated .i just can't think of another way to get rid of it
Ive stopped for the summer too ..it's far too hot right now so am doing a auto outdoor grow (my first ever) so wish me luck

 

[ilovethewest]

i dont think the attic is going to be the concern. i doubt if the heat from 1 light will even change the temp up there at all. my 2x 600w dont do shit to my attic, and i vent hot air up there and get my cold air from a foot away, im golden. the noise is what i get tripped out about, much harder to deal with. if your attic is acting up and becoming a security risk, then just run the vent to the out side of the attic.
flir.... fuck that. if your going to be popped, its not going to be because of flir. and you really think the popo want to go after YOUR 8 plants? and the heat signature off what your doing is so small, its only going to hurt your grow thinking about flir.

 

[greentrich]

Hey Rocket! Glad you stopped by. Just a thought, but in your case can you vent through your clothes dryer vent? I saw you were checking out an outdoor plot and was gonna ask how that goes over where you're at.

BTW...my UY tripped has been pushed back a couple months due to lack of monies (wife just had TWO surgeries...fucking doctors). But I'll update you later on that.

ILTW...thanks for the input bro. Sort of what I was thinking as well, just wanted to clarify. Plus like I said, if they're flir'ing me...I'm going down already. That's IF they decide I'm a big enough fish, which I'm not. This is all personal and a move on me would be a waste for them...since I don't contribute to the "war" they've been fighting LOL. Although I have heard a grow is a grow and they'll take you down no matter what. But I'm glad to hear that a puny little 400watter isn't going to affect the attic space.

Thanks man...been a lot of help!

 

[ITryToGrow]

I use 'A' and it works for me! And I studied hard before going with that choice. I had help from Redgreenry and his most excellent thread Vent 101. Check out my sig for more info. Good luck!

 

[rocket high]

hi gereentrich you dont have to pay for healthcare here we've got the NHS... so no big nasty bill's they take £2off your wages every week so you dont miss the £2 really ,
hope you get your ventilation sorted and i do too
the out door grow is going well so far but they're not outside yet but they will be next week .when it stops raining.

the noise is what i get tripped out about.

this is the biggest of my worry's i live in a apartment and i sleep next to my grow room ... it keeps me awake at night !!!!!
worry + noise = stress!!

on the flir note ..buy a house real near the airport they have to stop air traffic to get clearance ...and that hardly ever happens