How much venting is enuf with LED and a closet?

Yeah I know, google is your friend. But most of the HVAC threads seem to be about big operations, or at least big lights, so I'm being lazy and asking you guys.

What about a 2.5' X 3' grow structure (within a closet about twice that size) with an Area-51 XGS 190? Our house is well insulated and we don't have drastic summers/winters. Plant smell is another thing entirely of course, but I'm trying to address everything with one system. I'm thinking about buying a very quiet (.5 sone) 50 CFM bathroom fan and mounting it to the ceiling. Not cut into the ceiling like a normal fan, just attach it to the ceiling. Then install some creative ducting to expel air either to (A) the bedroom or (B) outdoors.

If plant smell becomes an issue, I have a theory. Bathroom fans have a flat face, hidden behind the plastic bezel. So I figure a guy could cut a piece of plywood, cut a hole in it for ducting, bolt it to the face of the fan, and rig a charcoal canister to the intake.

Anyway, here's the main question; is 50 CFM enough for a one LED/one plant closet grow?

I'd like to think it could be done with some PC fans but after hanging around here for a few weeks I'm guessing that'd be a waste of time.

Thanks for reading!

A 4" muffin fan can provide pretty decent air flow actually...

http://www.ebay.ca/itm/110-CFM-Axial-Muffin-Fan-Extra-Super-Quiet-Blower-Fireplace-120mm-AC-4-in-0020-/270988039995

Something like that.

Kind of depends on the strain/pheno, but some plants will have your whole house smelling. You're going to want to get some air moving in there so a fan/filter kinda helps with a few things. Good luck!

Edit: $100 will get you a brand new 4" inline/filter combo shipped..

The closet is approximately 196 cubic feet. There's always going to be losses due to ducting, or pulling through a carbon filter, or what have you, but at 50 CFM that'd be complete air exchange every 5 - 10 minutes. I'm guessing that's unnecessary. I don't think heat is going to be a huge problem with one mid-size LED panel. And if smell becomes an issue I should probably address that with carbon instead of increasing air movement beyond what's necessary to maintain temp. Right now the basic plan is to bring air in from floor level and evacuate near the ceiling.

My original post probably should have had something about air exchange guidelines in the title. Armed with a rough idea of recommended air exchange (for LED) one could quickly do the math for various spaces.

Shaded, you got me to thinking. I've got a few industrial duty 12V and 120V muffin fans from some old servers. Metal frames, huge motors. Very similar in appearance to the one you linked. A bit noisy, but I can slow them down. Maybe I'll play with those.

cherrypie, I've got the tools and most of the materials to try making a DIY carbon filter so that's kind of appealing even though a store-bought would be more convenient. EDIT: The more I read about DIY carbon filters the more I'm thinking about buying one. I guess Phresh is a good brand?

The proper way to ventilated a led grow is to observe and monitor temperature, relative humidity. Led lights dont generate the radiant heat like bids so ambient temp is measured and a heater with controls may be needed. Either way high temperature is not a issue and thus the reason you dont ventilated based on environmental temperature. But instead on environmental relative humidity, due to the plants natural transpires, a consequence is increased humidity. This increase slows down the rate at witch the plant can shed water. Thus hindering the rate of water/nutrient uptake, thus slowing down growth and creating nutrient salt accumulation in media further causing issues of lock out and high ph. At best a over water problem if you realize it early enough.
Moral of my rant..... ventilated based on RH and automate temp controls for night/day.

50 CFM is not enough
with a 196 Cubic foot tent you will start to build up stale air and heat. I have a system strong enough to exchange my air twice a minute through a filter then use a speed controller to slow it down an not run it full blast it also runs quieter. This will ensure that you have no smell issues. You will also need a recirculating fan to move air and keep the tent cooler. That LED in that amount of space will generate a decent amount of heat.

You may be correct about the light being able to heat the enclosure. I looked it up and saw the specks. It looks to be based on a color temperature and is of white lights. And be that as it may, would produce radiant heat. However at an actual consumption/usage of 190w max, that's peanuts dude. I have run 1000 actual watts and still have to use oil filled heaters at night and day, the frequency in which they run is dependent on the season.

The 50cfm is sufficient for the 1 - 2 plants that he has room for. Roughly 6 square if I remember correctly. Just run it 24/7.

Mellodrama said:

The closet is approximately 196 cubic feet. There's always going to be losses due to ducting, or pulling through a carbon filter, or what have you, but at 50 CFM that'd be complete air exchange every 5 - 10 minutes. I'm guessing that's unnecessary. I don't think heat is going to be a huge problem with one mid-size LED panel. And if smell becomes an issue I should probably address that with carbon instead of increasing air movement beyond what's necessary to maintain temp. Right now the basic plan is to bring air in from floor level and evacuate near the ceiling.

My original post probably should have had something about air exchange guidelines in the title. Armed with a rough idea of recommended air exchange (for LED) one could quickly do the math for various spaces.

Shaded, you got me to thinking. I've got a few industrial duty 12V and 120V muffin fans from some old servers. Metal frames, huge motors. Very similar in appearance to the one you linked. A bit noisy, but I can slow them down. Maybe I'll play with those.

cherrypie, I've got the tools and most of the materials to try making a DIY carbon filter so that's kind of appealing even though a store-bought would be more convenient. EDIT: The more I read about DIY carbon filters the more I'm thinking about buying one. I guess Phresh is a good brand?

Click to expand...

I have a 2x4x5' DIY cabinet I was using for 2 full cycles which will become my veg cabinet when I finish a new room. Not much different than yours size-wise. In that cabinet I started with a 120 cfm bathroom exhaust fan (already had it), nice & quiet, but not efficient. It did the job, but when I added a filter it had to work so hard that it was using a ton of power. Switched it to an inline fan, 4" is good for your cabinet, get a variable speed controller and most of the time you can use it on the lowest setting, much more energy efficient.

Someone else posted something here to the effect of watching your RH and measuring to that, good advice. I'm LED as well so the heat wasn't an issue other than during the warmest summer months. BUT humidity is/was in such a small space. Your plants transpire, the water in your pots evaporates etc. That's where I found the inline fan more efficient both at removing humidity and during the summer months it helped to reduce humidity and heat at about 1/2 the energy usage vs. the bathroom exhaust fan. It'll pay for itself in one grow and it's much easier to attach filters to it...

So I am growing in closet that is 2x4x8 and have a 2x3x5 tent within my closet. I just bought the Area 51 SDS 160. I got it going with some seedlings in my tent right now. This light runs very cool, as advertised just a couple degrees above your ambient temps. Before I had the tent I ran a 400W in that space and used a 4" inline ducted pulling air through the filter - hood and vented to attic. So I kept the inline fan setup and still using it with my LED. I am in Cali and my temps are 70-75 outside (sorry east coasters). I would recommend speed controller and you will prob run it 25% to 50% and maybe turn it up to 75-100% in the hot summer months depending on the ambient conditions. That fan does make some noise. I took it a step further and put the fan in the attic. I made a makeshift fan box with fan muffler which made it pretty quite. You can still hear fans but pretty stealth. I def recommend a filter, I use the Phresh....works well.

I am sitting at about 75 in my spare bedroom now (gets late afternoon soon).....my fan is running 50% power and I am at 78 in my tent. I just shut off the fan completely and opened the top two vents in my tent. Still have sep fan moving air around in the tent. My temp is up to 81.5 now. So it is easy to manage temps with your light. But it is still a good idea to refresh air, helps with humidity, plants grow better. I would also advise on doing it right from the get go instead of having to spend the time and money playing around with different fans trying to figure out what works, having to upgrade later etc.

GroErr said:

That's where I found the inline fan more efficient both at removing humidity and during the summer months it helped to reduce humidity and heat at about 1/2 the energy usage vs. the bathroom exhaust fan. It'll pay for itself in one grow and it's much easier to attach filters to it...

Click to expand...

We're greeners. So I'm feeling guilty about using electricity for an inside grow after all the steps we've taken to reduce our footprint. Where do you shop for inline fans? It'd have to be quiet and efficient...

Do you have a theory as to why the inlines are more efficient than a plain old bathroom fan? AFAIK most bathroom fans are squirrel cage and I thought that was an inherently efficient design.

Everyone makes good points, and I agree 100% that we'll have to monitor RH & temps. I'm just trying to get an idea how much horsepower will be needed to do this. From what I've gleaned on the forums, we need to provide some wind just to rustle the plant, and we'll need to evacuate air from the closet to adjust RH, temp, and smell. I'd hate to blow warm air outside during winter, so maybe with a carbon scrubber we can just blow to the bedroom instead some of the time.

rwbrock, message received - much better to be prepared from the start instead of cutting holes in the walls halfway thru the project.

Just did a quick Google - maybe something like this?

And GroErr mentioned throttling them - can you use something like a ceiling fan dimmer?

Mellodrama said:

Just did a quick Google - maybe something like this?

And GroErr mentioned throttling them - can you use something like a ceiling fan dimmer?

Click to expand...

That fan you sent the link to is typically called a booster fan, they are not as powerful or efficient as inline fans. They're also more open so they allow air in/out, even when they're not running. I'd recommend something like this one http://www.thelashop.com/inline-vent-duct-exhaust-fan-blower-4-inch-160-cfm.html. As far as the throttling, you should consider something like this: http://www.thelashop.com/hydroponics-inline-fan-blower-speed-controller-3-setting.html as they can handle the voltage/amperage for these inline fans. I'd imagine SOME ceiling fan dimmers might work but I've heard of issues with low end dimmers. The type I linked to is built for this and just plugs inline with the blower. The one's you linked to at The LAShop look like generic/no-name fans and variable controllers, you'd likely get a better price/deal online if you're going generic. I bought them on e-Bay for around $90 for a combo 4" Inline Fan and variable speed controller, some sell a combo of the fan, filter and speed controller bundled.