Struggling to improve my ventilation

Hi guys I have a room that I didnt design and that consist of:

22m x 10m x 4m

An extractor of 2600m3/h

3 AC on a closed circuit (they take the air from the room and spit it in the room)

4 humidifiers industrials
1 dehumidifier industrial

Co2 burner.

My main problem is that as my extraction is really low I end up having huge amounts of humidity wich is problematic in end flo.

One option would be to put more extraction but then it will counter effect the idea behind the AC. Like having AC in a car with windows opens.

Also it is a problem with the CO2, as I will have to make run the extraction only when the co2 is off (night)

Other possibility add more industrial dehumidifiers…

What would you suggest in this kind of setup?

Thank you for your help !

Edit: right now, 1k plants, next run around 3k plants in 7L pots in this set up is the project… 2 levels


How about some pictures of the current setup? It would make it easier to diagnose.


Hi mate thanks for your answering, not too sure how those pictures can help…


Well, my first question would have been, how high is your ceiling. Now that I see this, You my friend need an HVAC guy that actually knows his stuff.

You need to vent the room somehow. And the closer to the ceiling, the more heat you will pull from it. What’s on the other side of the walls?

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Since you are running CO2, then your only real option (for a closed co2 system) is to put more AC but pipe it in from outside the wall. If you move all your heat generating equipment (except lights) outside the room and have it draw the hot air into the A/C then get piped back in. The A/C is gonna get hot, so make sure it has enough BTUs to handle it. If you have big enough fans on the A/C, then it can make a cross breeze and possibly eliminate some fans and excess electricity. If you have enough room on the other side of the wall, I would do a waterfall cooler and route air through that before the A/C.

Check this out:


The ceiling is 4m high. I actually got an HVAC, but it has 2600m3 / h wich seems really low…
Thank you for your help…

The drivers are all out of the box, i mean I don’t reslly have for now temperature problems… 27-28 day, 22-23 night.

I got 4 AC in the room but they are on closed circuit so they are not connected to the outside of the room. They are on the ceeling.

I have a little amount of room between the ceeling of the indoor and the ceeling of the warehouse, what you recomend is to cool this area?

What about rising the amount of dehumidifiers? Thank you again for your time !


Sorry man. I think the issue here is your system is just not near big enough to handle the load. Call an HVAC dude and have him calculate what you really need. They have pre-written formulas for that kind of stuff.


I spoke to him yesterday when I told him I need the air to be renew each 1 or 2 mins he laughed at me saying this is imposible :no_mouth:

Im stuckkkk

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If you add one or two portable A/C units inside the room and pipe the waste heat out, that might be just what you need to lower humidity and manage the temp better.

If you have a crawl space or attic above the room, it needs to be vented. We had a camper trailer in the sun and it was always very hot. We built a shade over it and one tiny A/C was enough to keep it nice and cool inside. The reason it works like that is the level of airflow. The more air that passes between the roof and the inside, the less heat transferred. We built only the top. It had no sides to slow airflow.

Most likely, building a shade over the building is out of the question, but you might be able to vent the roof enough to make a difference.


Thank you I will proceed to the trials with what you adviced and will come back to some feedback soon !!

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By the way, that’s a great looking grow room. How are you growing? Soil? Hydro?


We are growing on soil.
Thank you, we got 3 racks for now and hopefully we will triple this between the harvest and the second run…

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You know, if you are going to make changes to the roof, Might I suggest roof vent fans connected to a small generator motor. Each roof vent will produce a few low amp volts, but it will take off the electric bill. PV panels where the vents are not.


Something like this on the roof connected to a motor? I suppose I would also need some batteries to store the electricity and some kind of inverter ? It is a good idea mate as here the electricity is deadly expensive…


Yes, That is the one. I think they make one with the motor inside already.


A solar concentrator (curved mirror) aimed at your PV panels will multiply the output.

You can also use an evacuated heat tube with a solar concentrator to run a small steam powered generator.


I suggest this because you have a large grow. You need every cost reduction you can get. Plus, being able to generate some of your own electricity means you will last much longer in case the power goes out.


Lotta holes and new metal. Anything can be done with the right contractors.


Multi layer growing has some unique challenges.

Do you have any destratification fans in the room? They are useful in mixing the hot, humid air that rides to the ceiling with the cool, dry air that likes to stay near the floor, helping to keep the entire volume of air in the room uniform in temperature and humidity.

What kind of ventilation/fresh air supply do you have feeding the lower level of plants? Most vertical growing systems are now using hot-air extraction vents placed between the lights and the layer of racking that supports the plants above it. Hot air from the LEDs is siphoned off and conditioned ASAP, and cool air is fed in from below the plants to help pull humidity up and through the plant canopy.

If you do go for the option of ventilation is your outdoor air dry enough to bring your growing temp and humidity into checking?

Also, have you considered following VPD to make the best of your room’s natural state? It can feel counterintuitive, but raising the temperature when humidity spikes can make the plants “feel” like they’re not in as humid of an environment.


Hi mate thank you for your help.

On the top layer I have some kind of fans that blow the air from the top. I will try to make some pictures.

On the bottom classic fans on feet to flow the air and small clips to make the branches move.

The system is on a -almost- close circuit system, so basicly the people that build this tried to bring as little as possible air from outside -contamination-.

Today I tried to cut the intraction/extraction as it was rainy.
I added 6 dehumidifiers but I didnt notice a big difference (from 2 to 3%)
I then restarted the int/ext and start playing with temps. Tried to move from 26 to 30 but the humidity started to rise a lot… I stopped at 85% as I didnt want to wipe the walls…

Then I dropped the temp from 26 to 18 and the humidity went to 56. The problem is I can’t schedule the AC so I raised again to 26 and tomorrow I will try to put cold air from the morning.

Dear company that made this indoor for where I work (I wont mention them as its a pretty big company in the us) if you read this please stop working in this industry.

Thank you for your answer, help and time guys… it’s great to have that nice community