10x10 Intake/Exhaust plan.....What do yall think? posiprops for help!

[Bob Smith]

FOR SURE ITS ALL ABOUT BUDGET...AND IF YOUR BUDGET CAN ONLY AFFORD ONE FILTER ECT THEN DO WHAT YOU CAN....BUT THE LINK I POSTED EARLIER HAS A FILTER AND 8" FAN FOR 180$....GETTING 2 OF THOSE IS CHEAPER THAN GETTING ONE BIG FILTER AND FAN....AND MORE EFFICIENT




I HATE SETTING UP AND THEN A FEW WEEKS LATER UPGRADING EQUIPMENT, THEN HAVING THE OLD EQUIPMENT SIT THERE USELESS....I LIKE TO TRY AND GET IT DONE THE FIRST TIME

^^^^What he said.

Save the funds up and do it right the first time; retrofitting a grow room after each grow because you've got more money and can buy more shit is a super pain in the ass - do it right the first time, you can thank us later.

 

[Incognegro]

Finally almost half way done setting up my room, i wanna run my air flow plans by you guys first since your advice has been so valuable in the past. If im doing anything newb or wrong PLEASE TELL ME! i will be dishing posi props out to all that help like i always do!

Basically my room is a 10x10, non sealed bedroom, running around 4-5k in lights. I want to run an intake/exhaust basic air circulation setup. Here is a picture of what i have planned...a 6-8inch 500 CFM fan with filter for intake, divided by a Y-pipe into two duct channels to supply air to the room.

Most importantly is the exhaust, i want to keep my humidity down. Il be running it in tandem with a dehumidifier and a 12k btu portable AC. I have exhaust running through an 8in fan capable of 800 CFM so it will fully change the air in the room very quickly, the air gets vented into my basement crawlspace and no carbon filters needed for now..for the hoods i will have oscillating fans aimed at each hood to keep the heat down..

My main questions are

1) is an 8in 800 CFM fan adequate to exhaust a 10x10 room

2) i know some people dont run intake, and just use negative pressure, but i want to have some nice cold air coming into the room since the laundry room is always nice and cold. the laundry room is also kind of close to my bedroom so id like the noise to be as low as possible...so thats why looking at a smaller less noisy fan.

my friend is running two 10x10 bedrooms with 5-7k each in lights and he has no AC. but he uses 12inch fans and ducting...he never has temp problems even during the summer..keep in mind we are in Oakland bay area where 80 degrees days are rare. do i need to go with 12inch or will 8 inch work?

1) No not at all. TRUE air filtration (at least to us painters), the air needs to circulate at least 5-10 in a minute to eliminate smells and VOCs. With growing the smell is not NEARLY as intense, but very distinct and illegal. So I try to use just as pressing measures. The least I would do is 3-5times air exchange. (In a minute)

We usually rate air equipment as we do sound equipment (we go by RMS not max)
MANY, MANY fans (whether squirrel, or centrifugal) are overrated, which is to be expected (they want your money.) So if a fan is rated for 800cfm, it's safe to knock off 20%. It's never a "bad" thing to have too much air circulation. So I say all that to say this..

Assuming you have 8foot ceilings, you're working with 800cf of air space. To cycle that (IMO, as I said I setup like I'm setting up another spray booth) So for 3times air exchange, you'll need to move 2400cfm, with the 80% true cfm, your fan needs to move at least 2880cfm (or 3000 for a even number). OR multiple fans that will equal the 3000cfm.

2) Intake is not ALWAYS necessary, ie, sealed room/ active exhaust/ a/c (a/c's usually bring in fresh air).

But if you're looking to introduce the air from another cool bedroom, why not just setup up your system to accommodate such? Meaning, attach ducting between the 2 rooms, and use THAT air as intake AND also to cool your lights?

If you were to get a fan, say a 8inch fan, and then get a 8x6x6 Y split, attach the intake of the fan to the other room, and attach exhaust ends (6inch sides) 1 to your lights, and let the other introduce cool air into the room. And if you're planning to exhaust into your basement (I'm assuming to expel heat) then you're temps should be good since you're cooling your lights with cool air, and going directly to exhaust. Though if you run all lights in tandem, you may need to either get a booster fan in the middle, or get a bigger fan.

Then you can apply both methods together (air filter and active intake)

You can run 2 lines of exhaust, 1 coming from lights, directly to basement (sealed air, so no smell), the other you can run air filter into another exhaust line, and if needed even tandem them together with a non-backflow valve duct.

Just my 2cents... My last couple of paragraphs, may be easier to understand if drawn...

 

[B. Friendly]

I'd be concerned about spending money on intake and exhaust when you could spend the money on co2 instead and increase your yeilds.

Just a thought

 

[250wscrogger]

I'd suggest two 10'' can max fans, two can 150's and two grozone tv-1 day-night thermostat/fan speed controllers... dump the exhausts into a 10''x10''x12'' Y splitter...12'' duct to outside....

this is what I'm doing for my 4k stadium (bare bulbs)

If you do this you won't need an intake fan and you won't need to aircool the hoods...I'd also suggest removing the glass on the hoods for more lumens and quicker bulb changes.

Exchanging the air every 30 seconds will also replenish fresh air and c02...





Another option would be one 10'' max fan and can 150 on a 8''x8''x10'' Y splitter and aircool the lights. Have the 10'' fan pulling hot air from the hoods/room and exhausting into the scrubber (outside of the room).

 

[Yes4Prop215]

K guys now im thinking about going with the dual exhausts like yall are saying....thanks again for all the advice props have been dished out.

would two 8 inch fans be louder than 1 12 inch? it might be easier to just use a 12in exhaust with no Y pipe? what do yall think...i have enogh room to run the double exhausts but im worried about two 8inchers sounding like a freaking airport in my grow room...

 

[rick shaw]

If you want it at its quietest design your airflow to be as straight and short as possible.Turns and severe reductions will cause noise. Wrap ducting in insulation.Make a DYI charcoal filter and put your money toward fans.

 

[Cannaseur Kid]

Gotta have twice the intake size as the exhaust for your exhaust fan to run correctly, boosted or not. Even if you do the one 10 in exhaust you should still have at least 2 passive 5 in holes for intake. That's like reducing a fire hose down on one end and hooking it up to your hose spigot in your yard... It's not going to work right...?

 

[Incognegro]

Depends of db rating of the fans, you could always easily construct sound chambers to reduce noise of fans... or add noise reducers inline with them.

 

[humble1]

would two 8 inch fans be louder than 1 12 inch? it might be easier to just use a 12in exhaust with no Y pipe? what do yall think...i have enogh room to run the double exhausts but im worried about two 8inchers sounding like a freaking airport in my grow room...

Without a doubt two 8" fans will be more noise than a dialed down 12". The quality of the motors and bearings on smaller fans is usually less than on larger, more expensive fans. I'm gonna get flak for this but who cares. Stick with simple. A nice 12" on a speed control and an appropriately sized carbon filter for exhaust will work just fine. Don't get CAN filters. They are obscenely large and heavy going up and especially coming down. I have a phresh filter that does the same amount of work that I hung and lowered myself. Unless you own the location remember that eventually you are going to have to patch the holes and one hole is easier to patch than two. Disregard the guy who says you need twice the intake than exhaust. Equal sized would create "balanced" pressure. Smaller intake than exhaust creates negative pressure. Your fan motors can take the resistance.

 

[real ting]

There is a lot of misinformation in this thread. Ventilation is all about pressure. A large sized exhaust fan will pull air in through your intake without having to worry about an intake fan. You can still run ducting to your laundry room if that is where you want to pull air in from, no intake fan is required. If that is the only intake hole then your exhaust fan will pull the cool air through the ducting and into the room. Just make sure the ducting has as few turns as possible, and that the overall size of the intake ducting is two times the size of your exhaust ducting. Rigid ducting flows much much better than flex duct, if you use flex duct you will want to use a massive size, or even double up and run two 14" depending on the size of your exhaust fan. If you run an intake fan your exhaust will never be able to run any faster than the intake fan is pushing air into the setup, limiting your exhaust at the intake. The other problem is you could push more air in than is going out, giving you positive pressure, which will push smelly grow room air out of any cracks in the room.

Check out the can max fan lineup. I haven't used these, I went with a smaller S&P fan, but I have heard great things, and the stats on these fans are great as far as noise vs airflow and pressure capability. However the different sizes have completely different stats. On can's website they list the cfm capability at different static pressures of their fans, which a lot of manufacturers don't do. Check out the chart here: http://canfilters.com/max_fan_home_2.html

An 800 cfm rated fan will never push anywhere near 800 cfms when installed in a grow room exhaust setup. I will use the 14" can max fan as an example since the numbers are published. Can says that their filters add .75" inches WG(water gauge, it's how they measure SP) pressure to a fan. So you hook up a carbon filter and your 1700 cfm fan is brought down to 1180 cfms. But you also need ducting, say you run a good length of ducting with a turn in it, and your exhaust ducting which might add another .1". Your intake has to be pulled through a length of duct that adds .1". Then your exhaust air has to push out of the holes in your crawl space, adding a further .05" At this point you are at 1" inches WG of static pressure. At this pressure your mighty 1700cfm 14" fan has dropped to just 240 cfm. So for this setup the 14" max fan would be a terrible choice.

Most fans we use for growing indoors will have huge cfm loss after 1" of static pressure. Most indoor grow rooms that utilize a carbon filter and ducting will be pushing that much pressure or more through their fans. So you may need a much large fan than you think, and always look at the static pressure charts to see if the fan you want can push enough cfms at the high pressures it will be under. Make it a priority to minimize pressure in your ventilation. As you can see in the charts, a small change of .1" can be a huge change in CFMS when you get above 1" of pressure.
You have to think about fan noise in terms of the motor noise of the fan running and the noise of the the air moving. As humble1 says, two smaller fans often will be more motor noise than a larger fan. Most fans get louder when they are working harder, or the more static pressure the louder the fan noise.


If you use two of the same fan in series, outlet of one fan connected to the inlet of the next, it boosts the static pressure capabilities. If you use them in parallel, next to eachother, the cfms are doubled. S&P makes a kit for connecting two of their fans in series, allowing them to perform much better at high pressures. Check out the mixvent fans catalogue, under TDX2-(fan number) to see how much of a difference it makes compared to a single fan. http://solerpalau-usa.com/brochures/Residential_Light_Comm/TD_Extended_Brochure.pdf

What humble1 says about intake size creating equal or positive pressure is untrue. The twice the intake to exhaust size rule of thumb is so that your intake is not adding static pressure to your system. If you use an equal size intake, but the intake is a 15' long run of ducting with a turn in it, then it will add a load of static pressure to your fan, which will slow it down considerably. By using double the size intake as exhaust you reduce the static pressure of your passive intake. You do not get rid of negative pressure by having a larger intake. The only way you are changing the balance of negative vs. positive pressure is by pumping air into the room with an intake fan.

There is no need for dual exhaust fans or filters if it is just one chamber. Go with one large fan and a filter fit to it. I would agree that can filters are heavy and a pain to put up with one person; I would not buy one again if I could find one of the lighter designs locally. Earlier in the thread incognegro recommends 3-5 times air exchange per minute. This works out to 4000cfms of airflow, requiring a fan rated somewhere above 10,000 CFMs and some kind of massive industrial filter. This is a little over the top. If you can achieve 1 turnover of the air per minute you will be doing well, which means you will want a fan that can hit 800 cfms at 1" or higher WG.

Now that I've finished my essay, I hope it helps. Good luck.

 

[real ting]

Gotta have twice the intake size as the exhaust for your exhaust fan to run correctly, boosted or not. Even if you do the one 10 in exhaust you should still have at least 2 passive 5 in holes for intake. That's like reducing a fire hose down on one end and hooking it up to your hose spigot in your yard... It's not going to work right...?

A 10 inch round hole is around 78 inches square of area, two 5 inch round holes adds up to roughly 40 inches of square area. It's a common mistake, but make sure you are figuring out the actual surface area of an intake or exhaust hole instead of using the diameter when comparing different sizes.

 

[Yes4Prop215]

There is no need for dual exhaust fans or filters if it is just one chamber. Go with one large fan and a filter fit to it. I would agree that can filters are heavy and a pain to put up with one person; I would not buy one again if I could find one of the lighter designs locally. Earlier in the thread incognegro recommends 3-5 times air exchange per minute. This works out to 4000cfms of airflow, requiring a fan rated somewhere above 10,000 CFMs and some kind of massive industrial filter. This is a little over the top. If you can achieve 1 turnover of the air per minute you will be doing well, which means you will want a fan that can hit 800 cfms at 1" or higher WG.

.

thanks alot yall are awesome...gotta alot to think about here. yeah i think since im saving money on not buying an intake fan im gonna just pony up and go for the 12in with 12in straight ducting....

also to solve the problem of a massive 12in filter cant i just put it in the corner or something? my friend has his filter verticly placed in the corner of his grow room, and the exhaust goes downstairs so its still straight.....

i have a closet in my growroom that i could also mount the filter on top of...it would just sit there, then i punch the walll and just run straight ducting to the crawlspace for exhaust...seems pretty simple.

 

[Incognegro]

Earlier in the thread incognegro recommends 3-5 times air exchange per minute. This works out to 4000cfms of airflow, requiring a fan rated somewhere above 10,000 CFMs and some kind of massive industrial filter. This is a little over the top. If you can achieve 1 turnover of the air per minute you will be doing well, which means you will want a fan that can hit 800 cfms at 1" or higher WG.

I'm glad there is finally someone who understands air pressure and etc. But alas, I think you misunderstood me, and the original posters "dilemma."

With his room assumably 800cf, 3-5times the air exchange would've been the 3000cfm. (3.75) but closer to 4 with the assumption that the fan is only 80% efficient.

I didn't apply the static pressure taking place since I mentioned the 2 separate fans, 1 for intake, the other for exhaust...

One must also take into account though the OP is running 6k worth of light/heat..

 

[Incognegro]

I'm curious how this plays out though, and see how you decide to set it up.

 

[humble1]

I'm out. Scientific theory has surpassed conventional wisdom and applied force in the same local area as the OP. Good luck and godspeed. I hope your intake hole doesn't whistle too much.

 

[rick shaw]

IMO the Max Fan by Can Fan is the best bang for your buck. The 12" is 1709 cfm. If you build your own monster filter and add a separate inline for the hoods I don't see it going over $800 for the entire exhaust system.

 

[foothill farmer]

Max Fan/Can Filter

Max Fan/Can Filter

I went with the biggest Can Filter and The 12" Max Fan (less than $800 from my local shop). It is nutz when I turn it on. Mine's a scrubber but it would exhaust your room in no time and you probably wouldn't even need an intake fan. Negative pressure will hook it up...

A duct muffler or plenty of insulation may be needed depending on how stealth you are trying to be. Putting it in a corner is a great idea!

 

[Yes4Prop215]

so my buddy who is running the double 5k setup was actually running 20k not to long ago, but toned down his grow. so he has an extra 12inch fan and ducting for me, i just gotta buy the filter!! he also gave me some free oscilating fans and two free 1000 watt hoods but i dont know i might return the hoods because i wanna buy XXXLs...

we are gonna mount the bigass 12 inch filter on top of this ikea closet that is in the corner. half will rest on the closet, while the other half will be connected to hooks in ceiling. then we are gonna punch a hole in the wall and just run a straight duct to the crawlspace.

its either that, or we set up the can filter vertically like foothill farmer, and run a small 90 degrees turn...but id rather have it straight piped so probably gonna mount it..

 

[250wscrogger]

If you buy hoods get super sun 2 or coolsun xl 8'' ....the XXXL's are too big/heavy.

 

[Yes4Prop215]

damn so my friend only has a 10inch fan for me not a 12....so heres the dilemna

go with the free 10in fan, or pony up and buy 12in?

what would yall do?