Cold Cellar Grow Room Learning the Hard Way

  • Thread starter MinerClan
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So I set up a 4x4 in a cold room in my basement

My thought was....

If the cold room stays cold and wet I can program the exhaust fan on the tent to kick in when it it gets to hot. Effectively bringing in the cold wet air that surrounds the tent.

I futher Ensure the air coming into the cold room from outside the house is filtered by a greenhouse hepa intake filter.

Usually in a cold room there is an intake and an exhaust that work passively with dampers to adjust air flow.

In this case I have created 3 rooms in the cold room.

One room is cold and wet. It receives the fresh air from outside. It is circulated into the second room passively to create air flow and keep the second room cool.

The third room is the 4x4 tent which exhausts its heat into the second room but intakes cool air from the first room.

You should see a tent and a small wall of insulation foam board with a hatch.
It stays 10 degrees c behind and at the sides of the tent.
But where I'm sitting and taking the photo it is 22 degrees c
You can also see silver flex ducting coming through the foam board. This is attached to tents 8 inch exhaust fan.
Just to the right of that is a 4 inch exhaust with booster fan it runs on low continuously helping to create air flow behind the tent.

Any thoughts?



Cut a hole in the wall with a hole saw or suck in cold air from outside through a window with your 4 inch fan or buy a mini split.


Minni split is amazing
I saw a nice one in action in someone's garage.

I'm very impressed with the way this settup is running.

I was told it would be expensive to try to usecold air from outside to cool your grow room.

However I found that if I don't bring the cold air directly into the tent I can add moisture to it or even warm it a few degrees before it enters the tent.

I haven't had any issues being able to keep high humidity for clones and seedlings.

Even when tent takes on cold fresh air it doesn't loose humidity. 65% RH while in Veg.

I was hoping someone could improve upon this concept or maybe point out a few flaws.

The cold air does enter the cold room from outside through a 4 inch inline duct fan and Hepa filter.


Grow for life🌱
Your going to have problems with that setup when your plants are transpiring heavily.
humidity will be off the charts.
might require multiple dehumidifiers.
you pull 10 degree air directly into the tent?
This idea works in theory, but needs to be adjusted accordingly.
some MacGyver shit right there.


I pull 10 degrees c directly in as needed usually every 15 min.

Humidity is regulated by a humidifier controlled by inkbird wiffi humidity controller and probe.

I do have a nice dehumidifier with a hose for draining and place in the cold room where the basement subpump is.

I know in the summer humidity will be highest in the cold room. It should be nice for my veg chamber.
But I cross my fingers the dehumidifier can keep it down in the flower chamber during summer.
Winter I know will be fine with humidity because the cold room is excepting dry air from outside. The Humidifier rocks hard right now to keep up with the constant dry. I even use a small float valve and 1/4 inch tube attached to a shower to keep it full.
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