Exhaust? How Much Do I Have To Have?

MAK1

Well-Known Member
What goes out first comes in. Air, humidity, heat, and COLD. Fall is here and soon the temps will drop.
My 3'x4'-6' tent is in a heated garage. All summer long I have been battling heat and humidity. Soon I will have to pay to heat all that exhausted air. I have read there should be enough exchange air to replace the volume every 2 minutes (optimal). How much exchange air do I really need? What is the less than optimal minimum?

I'm using 2-150 watt LED lamps and heat from the lights has not been an issue, the lamps are only warm. The circulation fans are also cool and the power head for the inline exhaust fan is outside the tent so no added heat inside the tent. The ventilation/exhaust fan is 400 cfm with an inline controller on the power cord, even with the controller turned down there is still lots of air flow.
I will get another controller, no worries there. Ambient humidity won't be problematic as flowering time approaches a low humidity time of year. Heating all that cold air is my concern.

Does someone have resource that will estimate a min-max? Like a graph of humidity/temp/air volume?
 

013

Member of the Month: Aug 2021
bump to move you to top of list

Prolly not the answers you were looking for but 1) look up VPD chart in search box above it gives thresholds for temp and rh but nothing on air exchange as far as I recall and 2) might need to raise your tent above the garage concrete slab for cold season. A covered or indoor concrete slab stays around 55 degrees in winter and only climbs to 56 degrees in summer. A slab can cause cold feet on your girks

I put down foam insulation and 2 pallets then put my tent on top of pallets

im going to ask @Rexer if he has any input
 

sneekymofo

Well-Known Member
I don’t know if you run your exhaust fan on a controller, but I spec’d mine to once every 2 minutes then I adjust my dial for heat, humidity, I once dreamt of CO2, and the like. Maybe you can do the same and dial it back. Wallyworld sells them for like 20 bucks. 013 is way right - the geothermal bonus you got from the floor is gonna be a killer in the cooler months. Maybe you can rig something that is easy to remove between seasons that buffers you from floor temps?
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oldmanjj

Well-Known Member

If you are in the states (other places may have them too), you can put them on risers like mine above. They drain nicely into a saucer for easy removal and the risers themselves would probably make a great place to put your stakes if needed.

My girls are on a basement floor and so far, knock on wood, they don't seem to mind.
 

sneekymofo

Well-Known Member

If you are in the states (other places may have them too), you can put them on risers like mine above. They drain nicely into a saucer for easy removal and the risers themselves would probably make a great place to put your stakes if needed.

My girls are on a basement floor and so far, knock on wood, they don't seem to mind.
Mine too, but carpet and pad add a little ‘extra’ between. I’m on a RDWC so everything’s gotta be level. Good idea tho!
 
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