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08-04-2012, 07:59 PM #11OPMember
12x12 room needs help converting to a grow room
I don't know what a open or closed system is but I will say that I want to have an AC and run exhaust out of the room. Can I do that with intake fans going to my attic? Also can you use that T-5 for whole process, start to finish? man, You are awesome!! I don't know you but I think you are so friggin awesome. Thank you for taking the time to tell me all this stuff. I can compensate you for you information if you would like because I really need this coaching.
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08-04-2012, 10:51 PM #12Senior Member
12x12 room needs help converting to a grow room
Originally Posted by biggz1115
you will need to figure out your heat output. this will warm the grow-on a side note grow at night. when its most likely coolest.
so if say you had 4 1000w lights in a 12x12x8 you would need the outside air to be 65deg to keep the temp cool enough for an exhaust to provide enough cooling. no ac needed in this case.
I say this because you would like to not have sealed lights. sealed lights loose 25% of the power potential in the glass.
So option b would be to get a 3 ton ac and keep the room at temp with it-can be a bit costly on this small of a grow.
option c is to vent the sealed lights, keeping the room sealed ( so you need an intake and exaust for the lights) and cooling or heating as needed from there.
You will find many calculations on the web for sizing a fan for ventilating indoor gardens; however, what many of these calculations fail to take into consideration is the friction loss on carbon filters and increased temperatures from HID lights. So here's my calculation method which you can use as a guide for sizing an exhaust fan for a growing area (keep in mind that this calculation will give you the lowest required CFM (Cubic feet of air per minute) required to ventilate the indoor garden.)
Step 1: Room Volume
First the volume of the room needs to be calculated. To calculate multiply length x width x height of growing area e.g. A room that is 8' x 8' x 8' will have a volume of 512 cubic feet.
Step 2: CFM Required
Your extraction fan should be able to adequately exchange the air in an indoor garden once every three minutes. Therefore, 512 cubic feet / 3 minutes = 171 CFM. This will be the absolute minimum CFM for exchanging the air in an indoor garden.
Step 3: Additional factors
Unfortunately, the minimum CFM needed to ventilate a indoor garden is never quite that simple. Once the grower has calculated the minimum CFM required for their indoor garden the following additional factors need to be considered:
Number of HID lights â?? add 5% per air cooled light or 10-15% per non-air cooled light.
CO2: add 5% for rooms with CO2 enrichment
Filters: if a carbon filter is to be used with the exhaust system then add 20%
Ambient temperature: for hot climates (such as Southern California) add 25%, for hot and humid climates (such as Florida) add up to 40%.
An Example
In our 8' x 8' room we have 2 x 1000w air cooled lights, and we plan to use a carbon filter. We also plan to use CO2 in this room. The ambient temperature is 90 °F (32°C), however, we will be using air from another room that is air-conditioned. Here's the minimum required CFM to ventilate room:
1) Calculate the CFM required for room (see above.)
2) Add 10% (for 2 air cooled lights.)
3) Add 5% of original CFM calculation (For CO2.)
4) Add 20% of original CFM calculation for Carbon Filter.
5) Air is coming from air-conditioned room so no need to add any other percentages.
6) CFM = (171 CFM) + (171CFM x 10%) + (171 CFM x 5%) + (171CFM x 20%) + ( 0 )= 231 CFM.
This is the absolute minimum CFM required to ventilate your room.
The next step might seem to match the closest fan to this CFM. However, for this example I'd choose a six inch fan with a CFM of around 400 or more, and a 6 inch carbon filter to match. The extra CFMs may seem a bit excessive (calculations on most indoor gardening websites would recommend a 4" fan and a 4" carbon filter) but it's always better to over-spec since we need to compensate for air resistance in ducting too.
Also, as we are using a carbon filter we will need to match the fan with the filter so that the fan that will neatly fit onto the filter.
If all the variables are kept the same and we changed the room size from 8' x 8' to a 12' x 12' then the minimum required CFM would be 519 CFM.
The All-Important Inflow!
An intake port can be anything from a gap under the door to an open window - even a hole in the wall. The best place for an intake port is diagonally opposite from your exhaust fan; that way, air has to pass across the entire room - very efficient. You can put a piece of screen over the opening to keep insects and animals out, a piece of A/C filter to keep dust out, or a louvered shutter or backdraft damper that opens when the fan turns on and closes when it turns off. You can also use a motorized damper. This gets installed in-line with your ducting and is plugged into whatever device controls your exhaust fan. When your fan turns on, it allows air to pass. When your fan shuts off, it seals completely, preventing CO2, air, etc. from passing. You can get creative with these devices and use one fan to control two rooms, etc.
One additional note about intake ports - you will see much better results from your exhaust system if you install a second fan to create an active (as opposed to passive) intake system. Normally, when your exhaust fan sucks air out of your room, air is passively going to get sucked back into the room. By installing a second fan on the intake side, you will reduce the amount of negative pressure created in the indoor garden, thereby cutting down greatly on the amount of work the exhaust fan has to do and allowing much more air to pass through. If you're not sure or you don't want to spend the money, start out with just an exhaust fan. If it's not performing as well as you thought it would, try adding an intake fan - you'll smile when you see the difference![align=center]Keep on Keepin on, it will all come together.[/align]
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09-22-2012, 03:10 PM #13OPMember
12x12 room needs help converting to a grow room
Wow. That's a lot to take in but I understand everything. The room is actually 12x10 and I have purchased a grow tent and I am using my closet in the room for veg. How would I go about ventilating the closet and light cooling and ventilation in the tent from 2 1000watt HPS Cool Tube lights? Someone else suggested that I start 2 mothers and clone off of them. How do I go about that? Also, when do I start using nutrients?
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