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phr3d0m2gr0
Red, I've read all 19 pages of this thread in hopes of finding a set up like mine will be, no such luck. I'll be building a 6'x6'x6' in a completly shaded basement with ambient outdoor temps and humidity quite high. I have to control temp & humidity,hopefully with a 5000btu window a/c, and a dehumidifier if needed, but can't add co2 because of stealth,this will be a sealed enviroment. I hope I can maintain 300ppm from small leaks and cracks? Planning on running a 600w with a 6" air cooled hood(total 8' long) maybee 6" ellbows on each end to block light,this would be the only restriction on the light vent. Planning fan and scrubber to work GREAT, what ever it takes??? If you're scrubbing the air and returning it in the same space does this create a balanced pressure or a accident waiting to happen? If it won't work,TELL ME! if you think its got a chance I would appreciate your opinons on fan size for lights, and fan and filter combo to make it work!!!
MBA I'll try to address three points in your post. (In order of appearance above)
First when you say outside ambient is high do you mean outdoors? If so what is the environment like in the basement. Is it pretty humid also? Does it get very hot (above 70F)?
Second when you say sealed do you mean that the cabinet will be sealed? Or do you mean that the basement will be sealed with no fresh air coming in?
If you mean that cabinet is sealed then you need to know that you must have some air flowing through a cabinet for it to work properly. Crack WILL NOT suffice for adequate inflow. Besides crack let light through and are less stealthy than a properly built intake vent.
If you mean the basement is sealed then this may also be a problem growing that large of a light. You will be able to grow plants fine, but with out an intake of fresh air containing CO2 the air may become over saturated with O2 so the plants may not grow as vigorously. With a 600w I'm not sure if this would be major concern though.
Finally about scrubbing and returning to the same area. If you have air flow THROUGH the cabinet and is then scrubbed and returned to the basement air environment it will be fine. There will be no pressure problems.
If you plan to scrub air and then just circulate it right back through the cabinet (the exhaust doesn't go to environment, but instead is connected to the intake) you won't have pressure problems, but you will have heat and CO2 problems. Again air can become too saturated with O2 and lead to less than optimal growth. The exhaust air would also be warm/hot and putting it back through the cabinet directly would just heat it up more. BAD IDEA.
Keep asking questions and keep reading as mush as you can until you understand how a grow cabinet works. It can save a lot of time and money, also don't expect to not make mistakes. They happen and it's the best and most memorable way to learn.
Good luck
-Phr3
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phr3d0m2gr0
RugerBaby Rather than rush to buy your equipment and make mistakes quickly, read more of the threads online. Search the forums for topics similar to your question "How many cfm?" or "what fan?" are simple starting points for searches.
Generally you need a certain amount of air to move through your grow chamber, this replenishes CO2. Look at the third post on this thread:
http://icmag.com/ic/showthread.php?t=66456&highlight=cfm
Then you need to provide enough flow to cool your light. Take a look at the chart in this post from the BEGINNING of this thread.
http://icmag.com/ic/showpost.php?p=2164612&postcount=6
Post six on the first page.
-Phr3
Generally you need a certain amount of air to move through your grow chamber, this replenishes CO2. Look at the third post on this thread:
http://icmag.com/ic/showthread.php?t=66456&highlight=cfm
Then you need to provide enough flow to cool your light. Take a look at the chart in this post from the BEGINNING of this thread.
http://icmag.com/ic/showpost.php?p=2164612&postcount=6
Post six on the first page.
-Phr3
Which monumentally sucks but, truer words were never spoken. Is there anyone who hasn't tested Mom's silly theory that fire is hot? OUCH! Not doin' that again.
PHR3, The basement is completly vented to the outside, I see this as my biggest problem, to control heat and humidity. Outside temps can reach 100 degs. with 95% humidity in the summer time. I thought I had to use a/c, but if I am exchanging the room air every minute or so The a/c would be useless. I was thinking if I vented the light hood outside the room(in the basement) and pulled (inside the room) air thru the filter with a seperate fan for odor it may pull enough fresh air in to be sucessful. I can't safley bring co2 bottles in and out, or propane, so I thought I could control more of the variables, HEAT,humidity, odor and hope to leak in enough fresh air to make it work!
Luigi4Bud
Member
Ok, I slogged through this topic and found it endlessly fascinating and endlessly confusing. I did learn the following:
I have a 4.5x4.5x7 tent that I know know is 141 cubic feet and that I would need a fan that was rated at 141cfm to remove that volume of air from the tent per one minute. I think I got that right, unfortunately, my comprehension level stalls at that point. So lets add a 6" air cooled hooded 400w HPS into the mix and that changes the numbers.
I believe that a two fan setup is important to maintain temps and odor, but if I could get away with one fan and maintain temps and odor, please tell me how.
Please let me know if this is well thought out
Fan#1 Fan inside tent in upper corner> short duct>filter. Fan#1 serves as outake for tent (with passive intake) and odor control through filter.
Fan#2 Vents the light, set up to pull air from outside tent through light and exhaust outside tent. I understand that this setup: fan, ducting, hood have to be sealed to prevent tent odor from exhausting through it.
If this setup is one that will work well for temp control and odor, my next question is.
What size fans?
My gut tells me two 6' S & P type mixeint fans would be more then enough and then I wonder if two 4" would do it. Or would the fan cooling the light need to be bigger or smaller then the fan drawing through the filter and the tent?
If I can get help on the fan sizes I should be looking at, I would also need help matching up the correct filter with the correct fan, which to me is the hardest part of this. Kudos to those on this thread for taking the time to share.
thanks
I have a 4.5x4.5x7 tent that I know know is 141 cubic feet and that I would need a fan that was rated at 141cfm to remove that volume of air from the tent per one minute. I think I got that right, unfortunately, my comprehension level stalls at that point. So lets add a 6" air cooled hooded 400w HPS into the mix and that changes the numbers.
I believe that a two fan setup is important to maintain temps and odor, but if I could get away with one fan and maintain temps and odor, please tell me how.
Please let me know if this is well thought out
Fan#1 Fan inside tent in upper corner> short duct>filter. Fan#1 serves as outake for tent (with passive intake) and odor control through filter.
Fan#2 Vents the light, set up to pull air from outside tent through light and exhaust outside tent. I understand that this setup: fan, ducting, hood have to be sealed to prevent tent odor from exhausting through it.
If this setup is one that will work well for temp control and odor, my next question is.
What size fans?
My gut tells me two 6' S & P type mixeint fans would be more then enough and then I wonder if two 4" would do it. Or would the fan cooling the light need to be bigger or smaller then the fan drawing through the filter and the tent?
If I can get help on the fan sizes I should be looking at, I would also need help matching up the correct filter with the correct fan, which to me is the hardest part of this. Kudos to those on this thread for taking the time to share.
thanks
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phr3d0m2gr0
Luigi4Bud you do have it correct that a 141 cfm fan would exchange air in your tent once a minute, but that is more ventilation than you need. You really only need to exchange the entire volume of air once every 3 to 5 minutes. That means you only need to flow about 50 cfm through the growing area. I would just go a little above that with a filter. If your buying a filter get one rated for around 75 cfm, then get a fan rated around 100+ cfm. The scrubber will slow the fan down and it will probably pull somewhere around 50-75 cfm.
For the light I would get something around 200 cfm or more. You'll only need a 4" fan and ducting for a 400w and 200 cfm should cool it down significantly.
-Phr3
For the light I would get something around 200 cfm or more. You'll only need a 4" fan and ducting for a 400w and 200 cfm should cool it down significantly.
-Phr3
As, I metioned earlier I would like to exhaust into my attic. Which would require at least 10ft of flexible ducting. Would an axial fan provide the proper amount of power to exhaust?
I would like to connect the exhaust and scrubbers exhaust into a Y connector then into the attic. Sound good?
where art thou Red?? lol
I need your help you ventilation wiz!!
I would like to connect the exhaust and scrubbers exhaust into a Y connector then into the attic. Sound good?
where art thou Red?? lol
I need your help you ventilation wiz!!
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guest 77721
This is the handiest chart that I've ever seen. It's based on a cooling formula that I've come across in a few places during my research.
CFM = 3.16 * Watts Dissipated / delta T in *F
If I had a dollar for everytime someone asked how many CFM's do I need for my Cabinet....
Here's a handy chart to for ventilation for each type of light bulb. For a simple cabinet use the 10*F curve.
For ventilated hoods and cooltubes, you can size your airflow to the exhaust temps. I'd recommend 20 to 30 *F. The hood traps most of the heat inside. The heat inside the hood stabilizes and is the same as the exhaust temp. With a cooled hood only the radiant heat from the light is transferred to the grow box.
Large rooms that connect several hoods in series to a common fan, 20*F per hood, and no more than 80*F total for the exaust temp rise.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Cooling lights and providing ventilation for your plants are two different things.
I believe more than One air exchange per minute is excessive and causes undue stress on the plants.
The one pass ventilation and scrubber designs that expose the plants to all the light cooling airflow cause unnecessary stress on the plants as well as requiring oversized fans and scrubbers.
It is better to cool the lights separately using ventilated hoods or cooltubes with unrestricted fans. This drops the requirements down for area ventilation significantly. I sure like putting in small fans and scrubbers which saves $$$ in equipement and operating costs.
*********************************************************************************************
Air Conditioner Sizing
BTU/hr = (3.413 * Watts) + (1.25 * Room Area * Delta T)
1 TON = 12000 BTU/hr
For example, a 144 sq ft room with two 600 W lights within 20* F of ambient would require
a 7700 Btu/hr or a 0.64 Ton unit.
CFM = 3.16 * Watts Dissipated / delta T in *F
If I had a dollar for everytime someone asked how many CFM's do I need for my Cabinet....
Here's a handy chart to for ventilation for each type of light bulb. For a simple cabinet use the 10*F curve.
For ventilated hoods and cooltubes, you can size your airflow to the exhaust temps. I'd recommend 20 to 30 *F. The hood traps most of the heat inside. The heat inside the hood stabilizes and is the same as the exhaust temp. With a cooled hood only the radiant heat from the light is transferred to the grow box.
Large rooms that connect several hoods in series to a common fan, 20*F per hood, and no more than 80*F total for the exaust temp rise.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Cooling lights and providing ventilation for your plants are two different things.
I believe more than One air exchange per minute is excessive and causes undue stress on the plants.
The one pass ventilation and scrubber designs that expose the plants to all the light cooling airflow cause unnecessary stress on the plants as well as requiring oversized fans and scrubbers.
It is better to cool the lights separately using ventilated hoods or cooltubes with unrestricted fans. This drops the requirements down for area ventilation significantly. I sure like putting in small fans and scrubbers which saves $$$ in equipement and operating costs.
*********************************************************************************************
Air Conditioner Sizing
BTU/hr = (3.413 * Watts) + (1.25 * Room Area * Delta T)
1 TON = 12000 BTU/hr
For example, a 144 sq ft room with two 600 W lights within 20* F of ambient would require
a 7700 Btu/hr or a 0.64 Ton unit.
Hey man, take a step away from the drawing board and take a breath.
You don't want to blow any of your air outside if you can help it. For air cooling hoods, it's best done by pulling air from outside, through a simple air filter (to keep the inside of hoods clean) and then blow through the lights, and back outside. If you blow room air out, it will smell, waste your cold, air condioned and dehumidified air ( that you paid so much to create) along with the heat.
You need an air conditioner and a dehumidifier, and to make it as sealed up as you can so that shitty outside air stays out of your room. I couldn't imagine trying to air cool a grow with ambient air like that. A lung room is ok too but it should be made of rigid insulation at least, panda plastic isn't great for these since they move so much air around.
As a rule, try to minimize ANY impact the weather outside has on your grow. Fighting mother nature is hard, expensive and frustrating, but if you seal the room so YOU are mother nature, you are going to grow more and better product.
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guest 77721
Hey Lazyman,
I'm providing the basic sizing calculations for light cooling and area ventilation. What I've found is that most of the information available comes from large indoor operations particularly greenhouses.
Most of the growers on this site are using growboxes for personal grows. A couple of lights inside a box in a bedroom isn't going to affect the climate of the house very much. All you need to do is cool the lights and scrub the growbox. Small growers are looking for stealth by using the smallest fans possible.
Large operations creating a great deal of waste heat may need more complex designs than a personal growbox in a bedroom closet. It is a huge waste of electricity to process all your waste heat using air conditioning. Using an outside air intake > sealed hoods > outside exhaust is far more efficient.
Personally, I think the future of an indoor farm is doomed. Smart metering will easily detect the signature of a growhouse and will find power thieves very quickly. Someone buys a house and suddenly it uses more power than a dozen houses. There's no future in this.
I'm providing the basic sizing calculations for light cooling and area ventilation. What I've found is that most of the information available comes from large indoor operations particularly greenhouses.
Most of the growers on this site are using growboxes for personal grows. A couple of lights inside a box in a bedroom isn't going to affect the climate of the house very much. All you need to do is cool the lights and scrub the growbox. Small growers are looking for stealth by using the smallest fans possible.
Large operations creating a great deal of waste heat may need more complex designs than a personal growbox in a bedroom closet. It is a huge waste of electricity to process all your waste heat using air conditioning. Using an outside air intake > sealed hoods > outside exhaust is far more efficient.
Personally, I think the future of an indoor farm is doomed. Smart metering will easily detect the signature of a growhouse and will find power thieves very quickly. Someone buys a house and suddenly it uses more power than a dozen houses. There's no future in this.
Sorry guys, I'm not explaining myself very well. I'm trying to run two seperate systems, one to cool the lights with ouside air and vent it staight back the outside. I will have a 5000 btu a/c for cooling, and a dehumidifier. I want to run a fan pulling thru a carbon filter exhausting in the room,for odor control ONLY. If I'm not exchanging my room air, will I get enough co2 in the room to be succesful? I'm thinking a 400cf/m fan for the light, not so sure about the carbon filter and fan sizing?. Sorry about the confusion, I really am trying to do this right, MINUS providing 1500 ppm/ co2.
gdbud
Member
Your cuft calculation in your spreadsheet for spaces is wrong this should be correctHi guys,
I see there's a backlog of questions. I'll try to answer them but please try to use my charts and tables. I really don't want to custom design everyone's growbox from scratch.
I've made another chart that might be more helpful to getting your basic airflows figured out.
One thing I'd really like to point out is that the ventilation requirements to remove heat from the light is far greater than what's needed for the plants.
Most of the small grow boxes and tents are blasting thier plants with an extremely high volume of air. I believe anymore than 1 ACpM puts undue stress on the plants.
If you can get all the heat out of the box, then the requirments for the scrubber drop way down. A small DIY filter powered by a computer fan is all a growbox grower needs to keep the smell down and give the plants a nice environment.
. L W H sqft cuft CFM@5ACpM CFM@3AcpM CFM@1AcpM
Pc Case 2 0.5 2.5 1 2.5 12.5 7.5 2.5
Wardrobe 2 1 3 2 6 30 18 6
Growbox 3 3 4 9 36 180 108 36
Closet 4 2 8 8 64 320 192 64
Tent 3 4 6 12 72 360 216 72
Bedroom 10 10 8 100 800 4000 2400 800
Basement 20 40 8 800 6400 32000 19200 6400
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guest 77721
Thanks gdbud. Great catch!!!
I had a column shifted in the spreadsheet.
I had a column shifted in the spreadsheet.
gdbud
Member
Sorry about that last post but the formatting on my number got messed up when it got posted, So I'm going to try again
PC Case, L=2ft, W=0.5ft, H=2.5ft, sqft=1 sqft, cuft=2.5 cuft
Wardrobe, L=2ft, W=1ft, H=3ft, sqft=2 sqft, cuft=6 cuft
Grow Box L=3ft, W=3ft, H=4ft sqft=9 sqft, cuft=36 cuft
Closet L=4ft, W=2ft, H=8ft sqft=8 sqft, cuft=64 cuft
Tent L=3ft, W=4ft, H=6ft, sqft=12 sqft, cuft=72 cuft
Bedroom L=10ft, W=10ft, H=8ft, sqft=100sqft, cuft=800 cuft
Basement L=20ft, W=40ft, H=8ft, sqft=800sqft, cuft=6400cuft
PC Case, L=2ft, W=0.5ft, H=2.5ft, sqft=1 sqft, cuft=2.5 cuft
Wardrobe, L=2ft, W=1ft, H=3ft, sqft=2 sqft, cuft=6 cuft
Grow Box L=3ft, W=3ft, H=4ft sqft=9 sqft, cuft=36 cuft
Closet L=4ft, W=2ft, H=8ft sqft=8 sqft, cuft=64 cuft
Tent L=3ft, W=4ft, H=6ft, sqft=12 sqft, cuft=72 cuft
Bedroom L=10ft, W=10ft, H=8ft, sqft=100sqft, cuft=800 cuft
Basement L=20ft, W=40ft, H=8ft, sqft=800sqft, cuft=6400cuft
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guest 77721
Hey MBA,
sorry for not getting to you for a bit. Your 600W cabinet doesn't need an AC or a dehumidifier to operate. A single 600W light needs 65CFM in a cooltube and 25 CFM of cabinet ventilation. If you can use outside air for the light then it means that you'll only have to run the AC on the hottest of days.
What you want to do is get as much heat out of the box as possible if you want to seal the growchamber up. I would recommend running 10*F on the lights or 190 CFM and try to drop the air exhange in the box below 5 MpAC or 5-10 CFM.
To maintain a high CO2 ppm, you'll want to exchange as little air as possible in the growbox.
sorry for not getting to you for a bit. Your 600W cabinet doesn't need an AC or a dehumidifier to operate. A single 600W light needs 65CFM in a cooltube and 25 CFM of cabinet ventilation. If you can use outside air for the light then it means that you'll only have to run the AC on the hottest of days.
What you want to do is get as much heat out of the box as possible if you want to seal the growchamber up. I would recommend running 10*F on the lights or 190 CFM and try to drop the air exhange in the box below 5 MpAC or 5-10 CFM.
To maintain a high CO2 ppm, you'll want to exchange as little air as possible in the growbox.
gdbud
Member
So let say I have a Grow Box that is L=2ft, W=2.5ft, H=4ft I have a space that has a cubic feet of 20cuft. At 5 air changes per minute I would need 100cuft/m or cfm air flow thou the cabinet.
Now lets look at the cooling of the light I'm running a 400 watt bulb with a cooltube at 100 cfm I will have a delta T of 15 degrees (my cabinet will be 15 degrees warmer than the air temp I will be bring into the cabinet).
I keep my space at 68 degrees (incoming air) So if I want my cabinet at 78 degrees that is a delta T of 10 degrees I would need 126cfm being pulled through my cabinet which would give me 6 air changes per minute.
Now lets look at the cooling of the light I'm running a 400 watt bulb with a cooltube at 100 cfm I will have a delta T of 15 degrees (my cabinet will be 15 degrees warmer than the air temp I will be bring into the cabinet).
I keep my space at 68 degrees (incoming air) So if I want my cabinet at 78 degrees that is a delta T of 10 degrees I would need 126cfm being pulled through my cabinet which would give me 6 air changes per minute.
