Ventilation CRISIS..once and for all. I need a solution.

so i have everything to make my grow cab. i just need to purchase the correct fan to keep my temps down...i have a couple seeds sprouting while i wait for Bog's Sour Bubble. I've done a lot of research and have been given a wide ray of selection...to tell you the truth..i'm stressing, so please help me figure a solution so i can just order this fan to finish my cab.

let me give you the run down of my box so you know what I am working with and what fan would be most appropriate.

The Cab:

(32in tall x 22in wide x 20in deep)

The Light:

250watt HPS

Also have a Pyrex bake-around-cool tube.

I plan to run a scrubber leading to the cool tube and then venting through the ceiling of the cab. or to save space i could have the cooltube last (pushing) and have that on the top exterior...either way i will probably use a rubber-made container on top to stealth the exhaust and silent it

...given my exact setup as you see it...if this was what you were working with...what EXACT fan would you purchase to properly vent and keep my temps down while keeping stealth...i just need to get this ordered...also, if you have a carbon scrubber suggestion along with it...that would be great.

thanks!

It isn't a crisis until you have plants dying. Get a squirrel cage blower or inline duct fan like everyone else. Blower is best for overcoming pressure but are usually somewhat loud. Or go to home depot and get a bathroom fan really cheap.

bump..no one???

i Know my options...but which is best suited for my setup...im sure many have run down this path and have experience in what they liked best...

I would recommend a 12" centrifugal fan because you would no longer need magnets to keep the doors of that cab closed.




Seriously, this site is a library of knowledge but nobody is going to read the books to you. Take a minute to find posts of grows with a cab similar in size to yours and see what worked for them. I am not trying to be rude but there is already tons of info on this site that would help you cool this space without waiting for someone to tell you what you want to hear.

BTW, nice work on the cab so far, a 250 will rock that thing and it won't be that hard to cool, I am sure it will all come together soon....

..im sure many have run down this path and have experience in what they liked best...

Click to expand...

Actually most people with small setups don't know what we like best, only what worked, didn't work, or what we made work.

Also, most small setups are very personal. As in how important is noise? Sure, it's important to everybody, but "baby sleeping in the same room" and "I don't want to hear it over the tv in the next room".

Personally sound is pretty important to me in a small stealth grow, so I'd probably pick up a panasonic whisper. Note I'm not vouching that I have one, just that it would be the one I'd buy.

Is it worth pointing out that your light is at 80 watts / sq. foot, when a 150w would light the cab effectively and drastically reduce your cooling fan needs, increasing stealth? Or are you already committed to that light + box combo? Just a thought.

Thanks Bugler, that's what I was trying to say but you were much more polite and tactful..

Big Twinn, apologies for lacking tack, Just go with more than you think you will need for cooling, it's alot easier to deal with too much cooling than not enough.... Check out some threads on here and you will be up and running in no time.

Aerohead's right. With an 250, you need a centrifugal fan. With 82wpsf, you've rendered anything short of looking like R2D2 impossible, lol. Seriously, check the other thread. Baba Ku mentioned several things you'll need to consider before recommending a fan.

Here's what I'd do depending on the circumstances. Get a 4" centrifugal fan and a compatible speed controller (not a light dimmer). Drill a 4" hole through the ceiling of the cab... (you need to check and see if there's room for a 4" hole after you test mount that honkin' hood, lol.) Mount the fan directly to the 4" hole in the cab ceiling. The joint can't leak or heat extraction will be less efficient.

External scrubbers aren't as effective as internal. To keep from blowing stink through cheap ducting (and it will stink) mount a 4" scrubber directly to the fan flange. Eliminate the duct and you eliminate 90% of the problem.

You'll have to take care if making your own scrubber, it can't leak air or it'll stink. Pushing through it will only expose potential vulnerabilities. Even if you have a lab grade scrubber, you'll have to seal the flanges or risk stink and or inefficiency.




Or..... you could trade that lamp in for a 150. With any luck you could diy a fan/scubber combo that fits inside, relieves technical difficulties and looks like and end table instead of a "what the fuck is that" kind of contraption.

Then again, a 250 will grow close to twice a 150. If you're still sold on the 250, best wishes.

I recently made a box very similar to that, only with a bit larger footprint. I was able to effectively cool (3-5 degrees above ambient) a 150w HPS in a cooltube with an 80 CFM Panasonic Whisperfan. I never put a 250 in it, but an extra 100 watts would have really taxed the ventilation system. You'll yield more with a properly ventilated 150 than with a 250 and high temperatures.

Whisperfans are relatively quiet (MUCH quieter than a standard centrifugal blower) but you will still be able to hear an odd humming and whooshing coming from a bedside table. People will ask questions. Whisperfans are also quite bulky, and removing them from the housing increases noise.

Good luck with this project, as it will be a challenge to maintain stealth, proper environment, and height is that cab with that lamp.

Ok so what would be the proper CFM rating for the Panasonic Whisper fan?? how about for a Blower???

http://www.westsidewholesale.com/ai...duct-low-profile-ventilation-fan.html?cfm=211

Done and done. It's not actually 100% silent, but you have to be within 5 feet of it to hear it.

I'd recommend using a vertical 150 watt. Just sayin..

So 80CFM is all i need??? while having a carbon filter? 110CFM seemed too little...anyone else think thats sufficient enough?? thanks!

keep in mind...im using a cool tube...so no hood

I would go with the 110 cfm panasonic whisperfan and build a flat tray style carbonfilter under it to save room. I use one in my ngb cab running about 200watts of led and cfl and it's a little overkill and the carbon takes literally just a few minutes to replace..



could you just cut a hole for the fan on top (like i did kinda) ...do the carbontray "box" thing venting out the back and just throw a cardboard or gutted rubbermaid over the top to hide the fan.....?

big twinn said:

Ok so what would be the proper CFM rating for the Panasonic Whisper fan?? how about for a Blower???

Click to expand...

big twinn said:

So 80CFM is all i need??? while having a carbon filter? 110CFM seemed too little...anyone else think thats sufficient enough?? thanks!

Click to expand...

bt, try to accumulate info from the posts you consider relative to your specific project. If you bank on the post that says "do this" it might not work for your situation.

80cfm was noted in relation to 150 watts of HID. If 110 doesn't do it for you, it pretty certain that 80cfm won't either.

Here's some math that might help. The ratio of lamp to air in the above scenario is almost 2:1. Based on this bit of info, I wouldn't buy a fan with less than a 2 to 1 correlation to your lamp.

To keep you from buying the minimum air-flow recommendations and having to upgrade your fan, get at least 150cfm from a centrifugal or minimum of 175 from a blower (the key being a fan drum as opposed to fan blade.) Axial fan blades don't handle the back pressure from scrubbers like fan drums do.

An even better suggestion is to buy a bigger than necessary fan and slow it down with a speed controller. This way you have the ability to increase air movement if necessary. A stronger fan on a speed controller will be quieter than a smaller fan on full speed. The bigger option will last longer and work better.

For example - 150 cfm centrifugal may work as well as a 175 to 200 cfm blower. This is because blowers don't handle back pressure as well as centrifugals.

You've got a relatively small cab for the lamp. You'll have to match the air system. Avoid the common tendency to beef up one element and compromise on the other.

Work out your system as a whole. It works best to pick components based on your finished design. Only then is tweaking the desired effect probable.

The reasons we know what works aren't always based on others' opinion. Sometimes we have to trial and error before we find something that manages to work well enough to grow indoors.

Your system is arguably the most complex aspect of your hobby. Don't look for specific answers as much as the comprehensive aspects you'll have to consider.

Baba Ku and others have mentioned aspects to consider before attempting the setup. Try a few hand drawn sketches of what setups you're willing to consider, ie internal versus external fan, push or pull through scrubber, external ducting, etc. Some of the recommendations you're getting might not be one of your personal options. Determining how you wish to proceed will narrow your options but you'll avoid or identify tips that go against your plan. In other words, we'll try to spare you any non-considerable suggestions. Best wishes with your setup.

StealthDragon said:

I would go with the 110 cfm panasonic whisperfan and build a flat tray style carbonfilter under it to save room. I use one in my ngb cab running about 200watts of led and cfl and it's a little overkill and the carbon takes literally just a few minutes to replace..



could you just cut a hole for the fan on top (like i did kinda) ...do the carbontray "box" thing venting out the back and just throw a cardboard or gutted rubbermaid over the top to hide the fan.....?

Click to expand...

exactly what i had in mind

DiscoBiscuit said:

bt, try to accumulate info from the posts you consider relative to your specific project. If you bank on the post that says "do this" it might not work for your situation.

80cfm was noted in relation to 150 watts of HID. If 110 doesn't do it for you, it pretty certain that 80cfm won't either.

Here's some math that might help. The ratio of lamp to air in the above scenario is almost 2:1. Based on this bit of info, I wouldn't buy a fan with less than a 2 to 1 correlation to your lamp.

To keep you from buying the minimum air-flow recommendations and having to upgrade your fan, get at least 150cfm from a centrifugal or minimum of 175 from a blower (the key being a fan drum as opposed to fan blade.) Axial fan blades don't handle the back pressure from scrubbers like fan drums do.

An even better suggestion is to buy a bigger than necessary fan and slow it down with a speed controller. This way you have the ability to increase air movement if necessary. A stronger fan on a speed controller will be quieter than a smaller fan on full speed. The bigger option will last longer and work better.

For example - 150 cfm centrifugal may work as well as a 175 to 200 cfm blower. This is because blowers don't handle back pressure as well as centrifugals.

You've got a relatively small cab for the lamp. You'll have to match the air system. Avoid the common tendency to beef up one element and compromise on the other.

Work out your system as a whole. It works best to pick components based on your finished design. Only then is tweaking the desired effect probable.

The reasons we know what works aren't always based on others' opinion. Sometimes we have to trial and error before we find something that manages to work well enough to grow indoors.

Your system is arguably the most complex aspect of your hobby. Don't look for specific answers as much as the comprehensive aspects you'll have to consider.

Baba Ku and others have mentioned aspects to consider before attempting the setup. Try a few hand drawn sketches of what setups you're willing to consider, ie internal versus external fan, push or pull through scrubber, external ducting, etc. Some of the recommendations you're getting might not be one of your personal options. Determining how you wish to proceed will narrow your options but you'll avoid or identify tips that go against your plan. In other words, we'll try to spare you any non-considerable suggestions. Best wishes with your setup.

Click to expand...

thank you for all the time you spent with such a well thought out and helpful post.

I have a few sketches i could upload if it helps. a few different sketches for various ideas.

a couple ideas being:

the scrubber attaching to the cooltube so that air is pulled through the tube with clean air then exiting out of the top where the fan will be placed and hidden by some sort of rubbermaid on top surrounding it and dampening sound.

the other option is having the cooltube open rather then the scrubber inside the cab and i could use PVC or attach it directly to the top exterior of the fan and have it hidden by the rubbermaid. this would save cabin space.

what it really comes down to, is finding the most appropriate fan. Im not sure how the panasonic fans are in relation to centrifugals. does Panasonic make a Whisper fan beefy enough for my system?? or should i be looking at centrifugals? if i understand correctly...you recommended 150cfm Centrifugal to cool my 250watts?? or should i take your advice and go bigger and keep it on a speed control??? what Db ratings should the centrifugal have???

Alright, we're making some progress.

The up-sides:You like the stealth of a whisper fan and the nominal headroom requirements of a whisper-type scrubber.

A potential down side is the sheer size. But don't fret, you've managed to gravitate toward possibly the most effective (smell) and efficient (heat removal) external-fan option available to your setup.

Panasonic makes AC and DC versions of their smaller fans. You're cooling 82wpsf, no small feat. If you're interested, check the 250 watt HPS club. Get an idea of the median cfm per setup. You've got a single chamber so back pressure from multiple chambers won't be an issue with efficiency in your case. This means you won't need the high side of air flow for extended back pressure reasons.

But you do have more watts per square foot than typical. Please don't minimize your air concerns. You'll need more exchanges of air with 3 square feet than you'd need with 5 square feet.

If and when you see a successful setup with 250 watts and 3 square feet, that's a specific you can plan on. (You may still have to tweak for your cab.)

Panasonic makes an 80cfm that works well with 150 HID. You'll need at least 100 but I'd play safe and go 120 minimum (and up to 150).

Here's the best part. You can cut a circular hole (the size of the fan intake) in the cab ceiling. Rather than have a centrifugal fan and conventional scrubber showing, you'll have a sheet metal box fan and a whisper-type scrubber on top. Not the alien eyesore I suggested earlier.

While we're at it, lets cover your passive intake requirements. If your exhaust fan has a 4" flange, you'll need two 4" holes for intake. Intake needs to be low as possible. Intake will have to be light trapped.

A 4" circular hole = 12.56 square inches. Two of these holes exceeds 25 square inches of area. You could cut a single, rectangular hole that approximates 25 square inches. For example, a 6" x 4" rectangle is 24 sq inches. That's close enough to work well.

Please avoid an active (fan-driven) intake. Please avoid the idea that 1:1 passive:exhaust will work. There are scores of threads tipping the respective op to modify passive intake from 1x exhaust to 2x.

discobiscuit knows his shit! make sure to rep him for the great help!

I just wanted to add that with the whisper fans you can't use a fan controller due to their design...(if you try to turn them down they gear themselves up automatically to make up for the loss in pressure!)so what I did is made a sort of "relief port" in the electric area to tone down the airflow a little..it's just a little piece of wood that slides in and out opening an additional intake port..adjusting that one little piece of wood helps me to fine tune my airflow and temperatures

big twinn said:

thank you for all the time you spent with such a well thought out and helpful post.

I have a few sketches i could upload if it helps. a few different sketches for various ideas.

a couple ideas being:

the scrubber attaching to the cooltube so that air is pulled through the tube with clean air then exiting out of the top where the fan will be placed and hidden by some sort of rubbermaid on top surrounding it and dampening sound.

the other option is having the cooltube open rather then the scrubber inside the cab and i could use PVC or attach it directly to the top exterior of the fan and have it hidden by the rubbermaid. this would save cabin space.

what it really comes down to, is finding the most appropriate fan. Im not sure how the panasonic fans are in relation to centrifugals. does Panasonic make a Whisper fan beefy enough for my system?? or should i be looking at centrifugals? if i understand correctly...you recommended 150cfm Centrifugal to cool my 250watts?? or should i take your advice and go bigger and keep it on a speed control??? what Db ratings should the centrifugal have???

Click to expand...

All your available avenues seem workable. At this point, it's a matter of your personal preference. Granted, one of your proposed options is best, technically. Another might be best, aesthetically. This is where direct testing and personal preference/experience trump my armchair quarterbacking, lol.

I like your rubbermaid idea. Out of sight, out of mind. Neat how little tricks thwart plain-view problems.

If you consider a scrubber on the end of the cool tube, you're limited to the linear dims of your cab. You could always shorten the tube/scrubber combo with ducting, making a "U" shaped tube/duct/scrubber assembly. Reducing length by half increases width more than double because of gradual curve in the duct. . It's a matter of what fits in your cab.

IMO, your second option is also sound. PVC beats cheap flex-duct and your ductless idea is cool too.

The length of your tube is going to play a role in the limited space. Even with the second option, (open tube) you'll need space to route the flex duct. Your duct will operate more efficiently with a gradual curve as opposed to 90 degree bend. The more gradual the curve, the more space required.

You may have to hold various options in place, judging whether feasibility is probable. If you get backed into a corner with no reasonable way out, it's time to consider another one of your options.

Types of exhaust...

This ones easy. IMO, centrifugal is the best option for pushing air through a scrubber. I think you'll do fine with a 150. A speed controller might allow you to reduce noise and a terminal scrubber will lend muffler qualities.

A member of the 250 club might be better to compare cfm needs. I've got 150hps on a 95 cfm blower - pulling air. My speed controller is on low and I have a 1" carbon wall scrubber, So the cfm throughput is possibly half or ~45 to 50 cfm. Conventional wisdom may suggest I don't need 95 cfm but the noise factor (turned to lowest speed) and back pressure from the scrubber says I do.

I would expect a 150cfm centrifugal, controller and scrubber to cool your needs. But you mentioned 110cfm didn't cut it without a scrubber. You either don't have enough intake or 110 cfm isn't enough exhaust. You could bank on a 150 centrifugal or you could get a second opinion from a 250 grower. They might recommend higher than 150 but I'm guessing.

Whisper fans are the best option for audible stealth. But they're blower-type and you might need a higher cfm rating than your base centrifugal need. Might be a good idea to search (by thread title) key words like "Panasonic", "whisper" etc. Whisper fans are mostly for smaller grows so you won't be weeding through room-size stuff.

S & P is a good line of relatively quiet in-line fans. Panasonic also has in-line fans in their whisper series.

Db ratings - This is where a speed controller will help, as long as your up-sized fan can handle your job at reduced capacity. Centrifugals typically run 40 to 50 db. Some ratings don't include ducting and some depend on the distance from the fan to measuring instrument.

The reason I went with a hydrofarm blower was the 29dB rating. It doesn't have the force needed to overcome back pressure as well as centrifugals but meets my requirements. The bearing(s) probably won't last as long but I paid less. My hydrofarm and scrubber also had the necessary right-angle configuration I needed to fit in my cab.

Whisper fans are measured in sones, not directly comparable to dB. We tried to estimate the noise from Panasonic's quietest model. Their dc 80cfm version (.3 sones) was compared to 17 db. But this was a sidewalk comparison that lends perspective rather than accuracy.

I'm a bit reluctant to specify type or size, even though several options will work good enough to grow indoors. I'd rather leave specifics to others that have similar hardware. Best of luck, you'll have a hulluva cab when you're done.

DiscoBiscuit: you are the MAN, an asset to these forums! thanks for all of your help.

for intake: i found this 8x8 dark room louvre...this will satisfy my light proofing needs and slightly bigger then 8X6 allowing more then a 2:1 ratio between intake and exhaust holes.

hmmm your two posts have me really thinking. Let me clarify that i have NOT tried the 110cfm fan...i wasnt saying it DID NOT work well for my setup, rather i was asking if this seemed high enough a rating.

i need to recheck on the panasonic whisper fans...i really like that route with what you provided in above...but i dont know if they make a fan higher then 110cfm

Thanks, ill keep you posted.

EDIT: maybe something like this?? http://www.nextag.com/Panasonic-FV-15VQ4-White-78825273/prices-html

big twinn said:

DiscoBiscuit: you are the MAN, an asset to these forums! thanks for all of your help.

Click to expand...

Thanks for the kind words. I'm happy to help where I can. The search feature nets the real invaluable info. I've only been growing indoors for five years. Some of our members have been around indoor growing for decades.

for intake: i found this 8x8 dark room louvre...this will satisfy my light proofing needs and slightly bigger then 8X6 allowing more then a 2:1 ratio between intake and exhaust holes.

Click to expand...

That should work well. Louvers throttle down throughput and an oversized louver is exactly what you need. Sorry I can't determine whether it's perfect but it's not likely you'll get positive pressure short of an improperly-tuned active intake.

hmmm your two posts have me really thinking. Let me clarify that i have NOT tried the 110cfm fan...i wasnt saying it DID NOT work well for my setup, rather i was asking if this seemed high enough a rating.

Click to expand...

Cool. Here's a good chance to test 110cfm if you want. If it doesn't work, you're closer to knowing what might/will.

I compare 110cfm (manufacturers rating) to bandwidth. Standing alone, the mfg claims 110cfm.

You won't get 110cfm when you add ducting, scrubber and the amount of back pressure your cab and components may generate.

With all your considerations, the "net" amount of air you get is comparable to throughput. If 110cfm nets the amount of throughput you need, more cfm isn't necessary.

But air flow is as important as the lamp itself. It's so important, I'd prefer to err on the strong side if at all. Erring on the weak side means headaches and possibly a fan upgrade.

i need to recheck on the Panasonic whisper fans...i really like that route with what you provided in above...but i don't know if they make a fan higher then 110cfm

Thanks, ill keep you posted.

EDIT: maybe something like this?? http://www.nextag.com/Panasonic-FV-15VQ4-White-78825273/prices-html

Click to expand...

Looks good. You may have to elbow the fan intake to the hole in your cab ceiling. You may have to locate the hole so that the fan rides on the cab as opposed to teetering on the periphery. You can use duct but Kolorblind says leaks will stink. They make ridged flex that's more durable than regular flex. It's sold in 3 or 4 foot sections, probably more than you'll need for the project.

Bulenath is the member I refer to as the Panasonic pioneer. Not only is he one of the first mentions, I think he conceptualized the scrubber so common on their ceilings fans. Last I read he was wandering India and enjoying the eastern life. I wish he would check in from time to time, I kinda miss him.

150cfm might give you enough oomph to quiet it further with a speed controller. If it's quiet enough, all you need is the intake to satiate the flow.

I wish I could be more precise but this game is often trial and error to non air system experts. I got my cab tuned but it was an experience I don't look forward to with the next cab, lol.

I'm sure there are Panasonic experts here.

Catman has a rockin' cab with a 150 hps and a Panasonic ceiling fan. He may have the 80cfm version but I'm sure he'd lend advice on your particulars.

I look forward to your success. You're gonna have one of those cabs that others aspire to copy. You'll make things lots easier for them, lol. Everybody wants the big, dense, dank buddage your cab will throw. Best of luck developing your thoroughbred.