Dehumidifier strategy, in the tent or lung room?

[BlueCrabGuy]

Hi Growers,

Looking for a dehumidifier strategy. My 4 x 2 is getting RH up to 65 at night when the air conditioner isn't running much. I would like to keep the RH in the 55% range. Should I get a dehumidifier to put in the tent or a bigger (more expensive to run) dehumidifier to control the RH in the lung room?

Thanks BC

 

[Dub_City405]

Room.

 

[LoveGrowingIt]

I have mine in my lung room.

 

[BlueCrabGuy]

Room.

Thanks Dub_City405. Approximately how much lower do I need to set the RH in the lung room to get the desired RH in the tent? Say I want the RH in the tent to be 55% would I set the lung room RH to around 40%? I figure it will take some trial and error to find the right combination. It is daytime and the air conditioning is running. The lung room RH is 38% and the temp is 71. My tent is running 54% RH and 75 degrees. Exhaust fan is only running at level 2.

These cold humid nights are killing me. They air conditioning is not running so that raises the indoor RH. The outside RH is in the 80's and that raises the indoor RH. The tent's light is off so it's not burning off humidity. The convergence of all three things raises my tent RH to dangerous levels for my flowers. Yikes.

Thanks again Dub_City405,
BC

 

[BlueCrabGuy]

I have mine in my lung room.

Thanks LoveGrowingIt

 

[BlueCrabGuy]

Any suggestions on a lung room dehumidifier? Should I go with one that uses a compressor? I read the compressor style ones are more efficient. The lung room is 12x12.

Thanks Growers,
BC

 

[Dub_City405]

This is where you learn your bang for the buck eliminates problems. You over size your dehumidifier. Put it in the room. Get a can fan or 2 and suck the air out of the top of the tent out into the room and blow into the tent at the bottom. Set it to 55 or 60 in the room whatever you desire. The air movement will even out the humidity.

 

[Trash_2002]

65% at night its perfectly fine tho.
What's the real problem is if there's dew/ condensation.

My dehumi schedule depends on outside climate aswell since my room.isnt sealed and I have a passive intake and active exhaust 80/100cfm for the lung room.

For example in very damp/cold weeks I need to set it at 50-55% at night to hit 60-65% I side the tents at night.
And same week I set It 55-60% during the day to hit 55-60% inside the tents.

Hot and dry weather I set it to 65% during the day to be in the 55-60% range inside.the tents and 55% at night.

You have to study your dehumidifier setpoints for your particular situation and weather conditions.

Also feeding/watering days are particularly more humid there's many variables, you could use a inkbird humi/dehumi controller, but I find more accurate to.set it by hand for each particular day/week.

Right now it's cold and damp outside, dehumidifier is set to 55% it's the second hour after flower lights out and the peak RH was 66% from there it will drop during the night to 60%.

Veg it's still with lights on and dropping, it will drop below 50% last lights on hours probably.

 

[Trash_2002]

This is one tent RH behaviour at a very damp and cold outside night, peak RH first 2 hours dark, than drop and drop.
If you see the peak that night was 72% but ended at 60% and an average of 65%, and the most important no condensation and lots of air movement inside the tents with negative pressure.
Also don't mind the vpd at night in my graphs since it's with the leaf surface differential (need to add 0.55kpa for a accurate night reading)

 

[Trash_2002]

I need to buy a timer for the lung room exhaust so I can shut it off at night to not pull in humid air while lights are out to help the dehumi work easier.... But in reality most of the weeks where I live it never go higher than 65% at night inside the tents witch is totally fine. Never had bud root or any wpm in this relativity "new" room witch has been active for almost 2 years now.

The room is almost 12x12 and the dehumidifier is rated to 30L/day, ~400w power.

 

[Trash_2002]

The other trick many people use when possible, is to invert your lights on cycles to be at night hours, so you average better your temperatures and RH, also pay less electricity at those hours.

 

[Trash_2002]

Another cold damp night (10c RH 85%+ outside), one day after the feeding day the RH peak is already ~5% lower.
Rh is very dinamic, I just don't want it to go any higher than 70% at night, and never ever hit dew/condensing point that's the most important thing, following that you will be fine together with good extraction for the tents, 6inches exhaust at full power 24/7.