Exhausting Stale Air In 4x8

Sealed or non-sealed?

  • Total voters
    2
FunkyPunk420

FunkyPunk420

Active Member
I recently posted a thread about putting a portable air conditioner inside of a 4x8 tent and someone suggested that I could put the tent exhaust on a timed cycle. That way I don't expend the cool air until co2 needs to be replenished and new air be brought in.

My questions now are
  1. How often should I replenish the air and exhaust the tent? (i.e. How long until the plants are deprived of Co2?)
  2. How long should the intervals last? (i.e. How long should the fans stay on?)
  3. Would a sealed tent be more cost effective? (i.e. Cost of a/c Vs. Cost of Co2)

Specific details
  • Exhaust from a/c and tent will go directly outside, not into lung room
  • Tent exhaust will have carbon filter in tent mounted on 8" inline fan
  • Intake will be another 8" inline fan
  • Lung room is garage with poor insulation and high temps exceeding 110 in summer
  • No other options except tent growing
 
Last edited:
Givingstifftothestiff

Givingstifftothestiff

Well-Known Member
FunkyPunk420 said:
I recently posted a thread about putting a portable air conditioner inside of a 4x8 tent and someone suggested that I could put the tent exhaust on a timed cycle. That way I don't expend the cool air until co2 needs to be replenished and new air be brought in.

My questions now are
  1. How often should I replenish the air and exhaust the tent? (i.e. How long until the plants are deprived of Co2?)
  2. How long should the intervals last? (i.e. How long should the fans stay on?)
  3. Would a sealed tent be more cost effective? (i.e. Cost of a/c Vs. Cost of Co2)

Specific details
  • Exhaust from a/c and tent will go directly outside, not into lung room
  • Tent exhaust will have carbon filter in tent mounted on 8" inline fan
  • Intake will be another 8" inline fan
  • Lung room is garage with poor insulation
  • No other options except tent growing
Click to expand...
If you're using a single hose portable A/C you're already venting the tent via the exhaust, so if smells an issue you'll need to filter it aswell
 
FunkyPunk420

FunkyPunk420

Active Member
Givingstifftothestiff said:
If you're using a single hose portable A/C you're already venting the tent via the exhaust, so if smells an issue you'll need to filter it aswell
Click to expand...
Great point! I didn't consider the exhaust from the a/c

Does that render the idea of a sealed grow completely useless? Since the a/c will exhaust some of the added co2?

I know that they have a dual hose a/c but i do not have/cant afford one.
 
NukaKola

NukaKola

Well-Known Member
So the thing about running CO2 is you can run the room hotter which saves on cooling as well.

Typically you would run a room ~78F for HID lighting and ~82-85F for LED lighting if you are not supplementing CO2.

If you are supplementing CO2, people tend to run ~83-85F for HID lighting and ~85-89F for LED lighting.

CO2 also has the potential to yield ~30% more.

What I would do, is seal up your tent by remove the intake/exhaust and add a CO2 tank. Keep the portable AC mounted outside your tent feeding the air in through the side like you currently have it. This means the AC will intake air from your garage, the cool air will go into your tent and the hot air will be exhausted through the AC's ducting. This will prevent the AC from expelling your CO2 out of the exhaust. If you mounted the AC inside the tent it would waste your CO2.

The only problem with this solution is that you may need to buy a thermostat and plug the AC into it and hang the temp probe inside the tent. AC's usually have the temp probe on the intake grill, and since the AC unit would be mounted outside the tent it would be sucking in air from your garage which would end up being a much higher temp then the air inside your tent. So for instance, if your garage is 90F and you set the AC to 80F, once the tent reaches 80F the AC will keep running because it is reading the temp from the 90F air in the garage and will continue cooling the tent below your 80F target temp.

This is the thermostat I use, fairly cheap and works well.

 
Givingstifftothestiff

Givingstifftothestiff

Well-Known Member
FunkyPunk420 said:
Great point! I didn't consider the exhaust from the a/c

Does that render the idea of a sealed grow completely useless? Since the a/c will exhaust some of the added co2?

I know that they have a dual hose a/c but i do not have/cant afford one.
Click to expand...
You can mod a single hose unit, you need to build an intake box and use it to seal the air inlet to the motor then run a duct out of that.

If you haven't got a fully sealed room you won't get the full benefit of added Co2, you might get some benefits by adding it but you'll go through a lot more gas trying to hit the levels needed
 
FunkyPunk420

FunkyPunk420

Active Member
NukaKola said:
What I would do, is seal up your tent by remove the intake/exhaust and add a CO2 tank. Keep the portable AC mounted outside your tent feeding the air in through the side like you currently have it.

Click to expand...
When we were in the height of the summer I got the a/c and when I set it up initially I did the grow hack where you get a cardboard box and affix it to the a/c unit, attach ducting and a booster fan and feed it into the tent.
This did not work at all.
I tried to turn off the exhaust fan to see if that would work better and temps started to climb to my surprise. I tried keeping exhaust on a low setting, on a high setting, Cutting off the booster fan, cutting it up, nothing worked.

I have since then, opened the side zipper and sealed directly around the a/c as you seen in my previous post.
Even though it works better even if I cut off the exhaust fan now the temps still don't get to where I desire when it is really hot.

I really appreciate you guys trying to get my system to work but I think it just gets far too hot in my lung room. Temps in my garage will get up to 120 in summer with all the fans and other electrical components. I don't think the a/c in its current setup is capable of cooling that hot air 31 degrees to reach 89.

I am scratching it out and moving on to what could possibly work and that ( I feel ) would be putting the a/c directly inside so it can cool the air that it has already cooled, as opposed to cooling the hot air in the garage over and over.
 
FunkyPunk420

FunkyPunk420

Active Member
NukaKola said:
So the thing about running CO2 is you can run the room hotter which saves on cooling as well.


The only problem with this solution is that you may need to buy a thermostat and plug the AC into it and hang the temp probe inside the tent.

Click to expand...
I also have the A/C hooked up to an inkbird temp controller already. I have to raise and lower the SV with the weather otherwise the a/c will run constantly.
 
FunkyPunk420

FunkyPunk420

Active Member
Givingstifftothestiff said:
You can mod a single hose unit, you need to build an intake box and use it to seal the air inlet to the motor then run a duct out of that.

If you haven't got a fully sealed room you won't get the full benefit of added Co2, you might get some benefits by adding it but you'll go through a lot more gas trying to hit the levels needed
Click to expand...
So if I am doing a sealed grow I would have to rig that up... let's just say -1 for sealed grow.

How do you mean though? I would have to disassemble a/c? If so I'd rather not.
 
NukaKola

NukaKola

Well-Known Member
FunkyPunk420 said:
When we were in the height of the summer I got the a/c and when I set it up initially I did the grow hack where you get a cardboard box and affix it to the a/c unit, attach ducting and a booster fan and feed it into the tent.
This did not work at all.
I tried to turn off the exhaust fan to see if that would work better and temps started to climb to my surprise. I tried keeping exhaust on a low setting, on a high setting, Cutting off the booster fan, cutting it up, nothing worked.

I have since then, opened the side zipper and sealed directly around the a/c as you seen in my previous post.
Even though it works better even if I cut off the exhaust fan now the temps still don't get to where I desire when it is really hot.

I really appreciate you guys trying to get my system to work but I think it just gets far too hot in my lung room. Temps in my garage will get up to 120 in summer with all the fans and other electrical components. I don't think the a/c in its current setup is capable of cooling that hot air 31 degrees to reach 89.

I am scratching it out and moving on to what could possibly work and that ( I feel ) would be putting the a/c directly inside so it can cool the air that it has already cooled, as opposed to cooling the hot air in the garage over and over.
Click to expand...
Yeah it definitely would be hard work on the AC to cool with that kind of ambient temp. The only issue with mounting it inside is you would not be able to use a CO2 tank, and would still need some type of fresh air intake cycling on to replenish C02. If you ever end up upgrading your AC, window units work much better and smaller ones are fairly cheap. They are more efficient and recirculate the air so they won't waste CO2. You could rig a window unit up to your tent and run it sealed with CO2.
 
FunkyPunk420

FunkyPunk420

Active Member
NukaKola said:
You could rig a window unit up to your tent and run it sealed with CO2.
Click to expand...
I appreciate your help, time, and suggestions very much! Thank you! But I dont think a window unit is an option either because then it would be exhausting directly into my garage? Again thank you so much for your suggestions, they are helping me to explore every option.
 
NukaKola

NukaKola

Well-Known Member
FunkyPunk420 said:
I appreciate your help, time, and suggestions very much! Thank you! But I dont think a window unit is an option either because then it would be exhausting directly into my garage? Again thank you so much for your suggestions, they are helping me to explore every option.
Click to expand...
To vent out the heat from your garage you would have to connect your in-line fan as an exhaust using the hole you are currently using for your portable AC exhaust.
 
FunkyPunk420

FunkyPunk420

Active Member
NukaKola said:
To vent out the heat from your garage you would have to connect your in-line fan as an exhaust using the hole you are currently using for your portable AC exhaust.
Click to expand...
I'll keep that in mind brother appreciate it. Any advice on the OP questions?
 
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