Need expert's help with exhaust configuration !!!!

Hi all !
I'm having a hard time setting up an exhaust system to exhaust 3 different grow tents .
Need to know if this set up can work with a good negative pressure and no leaks .
I got a big aluminum ducting box made for house thermo ventilation , it has 8'' holes on sides and one 12'' hole on top.
I currently have 1x8'' vortex fan in each 8x8 tent and 1x4'' canfan in the 5,5x5,5 Veg tent .
I still have to buy the maine inline fan sucking in all exhaust and pushing it out threw 1 x 8'' whole going outside. Wondering if a 10'' is enough or should i take a 12'' (11450cfm).
Note-
-each tent has 1x10,000 btu portable a/c .
-First 8x8 tent runs 12 hrs then second 8x8 tent runs 12 , so on .
-5,5x5,5 veg tent runs 24/7.

BUMMMMPppppppppp

Thought of another way that might be possible..

I'm no expert, but I think the first configuration might push air backwards thru the A/C's, while the second would not. The portable A/C's are known for being inefficient. Cooling the air and immediately sucking it out will be very expensive. Venting an air conditioned space is counterproductive. Have you considered a sealed grow? You seem to have everything you need but co2 augmentation, assuming the A/C's are the two-hose type.

Red1966 said:

I'm no expert, but I think the first configuration might push air backwards thru the A/C's, while the second would not. The portable A/C's are known for being inefficient. Cooling the air and immediately sucking it out will be very expensive. Venting an air conditioned space is counterproductive. Have you considered a sealed grow? You seem to have everything you need but co2 augmentation, assuming the A/C's are the two-hose type.

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Yeah your right , what exactly is a sealed room?

I use a canine co2 generator while circulating air through out the house. The central A/C takes care of cooling. You want to make sure you have good odor control if you do this.

Grow4tho187 said:

Yeah your right , what exactly is a sealed room?

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A sealed room doesn't exchange air with the outside. It requires some sort of air conditioning to keep it cool and to keep humidity down. Also, you will need to add co2 because your plants will use up all the co2 normally present. No co2 equals no growth. The A/C needs to be sized correctly so the it does a good job dehumidifying the air. This can be difficult to achieve, so most add a dehumidifier, too. I used to grow in a sealed tent, but my A/C (smallest one I could find) was too powerfull to run more than a couple of minutes at a time so I had to add a dehumidifier. The dehumidifier pushed my power consumption way up. Beyond what the house wiring could support. I switched to just circulating the air through out the house with an additional window A/C in the grow room. The dog seems to provide enough co2 when no one is home. The lights are off during the day anyway. I haven't noticed a lack of co2 and I did check it with one of the test kits. Bear in mind my grow is only 2x600 watts of lights, so my experience may be different than yours. Again, a good carbon filter is a must!

I'm not sure I'm getting this right .. lol where will the hot air go? how can u maintain a negastive pressure inside the room if not exhausting the room ? Can 1 of you either make a lil scetch with microsoft paint or explain with more details sorry im a bit slow tonight i have alot of things on my mind.

Grow4tho187 said:

I'm not sure I'm getting this right .. lol where will the hot air go? how can u maintain a negastive pressure inside the room if not exhausting the room ? Can 1 of you either make a lil scetch with microsoft paint or explain with more details sorry im a bit slow tonight i have alot of things on my mind.

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The hot air is cooled and recirculated in the room. It stays in the room. There is no need to maintain negative pressure in a sealed room.

But a/cs push in air? where is the etra aire going?

Red1966 said:

The hot air is cooled and recirculated in the room. It stays in the room. There is no need to maintain negative pressure in a sealed room.

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• But a/cs push in air? where is the etra aire going?​
  
  
  
  

Grow4tho187 said:

But a/cs push in air? where is the etra aire going?

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A window A/C or a mini-split pulls in hot air from the room, cools it by passing it over the coils, and then pushes the now cool air back into the room. It's just the same air recirculated over and over. That's why it's necessary to add co2 as the plants use it up.

You'll get back flow unless all of your fans are on at all times. the only other way to prevent this is to either put check valves in each line or to put a fan sucking from the main choke point.

Red1966 said:

A window A/C or a mini-split pulls in hot air from the room, cools it by passing it over the coils, and then pushes the now cool air back into the room. It's just the same air recirculated over and over. That's why it's necessary to add co2 as the plants use it up.

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A window a/c has hot air coming from the back.. I have a friend who sells and instals mini splits , ima lookin to that thanks

I wouldnt want him to insal it tho lol , A mini split cant be that hard to instal..? make a whole pass the wiring , well custome fitted pipings ..? I'm sure there's a step by step do it your self video on youtube lol

Grow4tho187 said:

A window a/c has hot air coming from the back.. I have a friend who sells and instals mini splits , ima lookin to that thanks

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It is pulling in cool outside air from the sides, heating it by pushing it over the condenser, and pushing it out the back. But there is some unwanted exchange with the interior air, due to poor construction, so you are partially correct. Newer units exchange less air, but still some. You are correct that the mini-split is a better option. If you have a friend that can install it for you and won't report your "garden", you're golden.

Red1966 said:

It is pulling in cool outside air from the sides, heating it by pushing it over the condenser, and pushing it out the back. But there is some unwanted exchange with the interior air, due to poor construction, so you are partially correct. Newer units exchange less air, but still some. You are correct that the mini-split is a better option. If you have a friend that can install it for you and won't report your "garden", you're golden.

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I just finished watching a do it your self video of how to instal mini split .. bro! thing is easy !
Dont even need to weld a thing .

http://www.youtube.com/watch?v=PdMRVO_NOz4

I do use a sealed system during the summer. I usually have the exhaust fan handy with the filter. Just use the exhaust during lights off every 3 hours for 15 minutes to exhaust the stale air and reduce the RH.

Grow4tho187 said:

I wouldnt want him to insal it tho lol , A mini split cant be that hard to instal..? make a whole pass the wiring , well custome fitted pipings ..? I'm sure there's a step by step do it your self video on youtube lol

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There is a company that supplies "do it yourself" kits for mini-splits. Compressor, evaporator, quick connect hoses, the whole thing. Can't recall them name of the company(s), but a quick search should find them. You may need to do some wiring.

I see you beat me to the punch.