Dehumidifier doing what??

[intotheunknown]

this is the first time having to use a dehumidifier. and im not having much luck with it. not too sure what im doing wrong if anything.

let me layout my situation.

5x5 secret jardin inside its own room.

pushing air into that room with a 600 cfm duct fan

removing the air through a scrubber, cooling a 1k hps and out to a room upstairs with an 8" 765 cfm fan. passive intake air into the tent.

and a window air conditioner built into the room wall, there when i need it. and temps are always perfect.

and inside the tent a 20L dehumidifier i run only during the dark period. zero ventilation. only the passive intakes in the tent open, and air circulating.

the first dehumidifier i bought didnt work at all. it actually added 20% humidity to the environment, and didnt pull a drop of water out of the air (obviously defective)

exchanged it, and this one is working as far as pulling water out of the air, but is still adding some humidity...

i dont believe it to be undersized, as explained in the manual as far as its capacities, etc go.

anybody have any experience with a dehumidifier doing opposite its job? any suggestions as to what i may be doing wrong?

 

[guyyug]

I don't see how a dehumidifier can work if you are not keeping the room sealed. If you have an a/c and a dehumidifier, seal that room up. Grab a co2 tank and you are golden. What is the humidity where you live? Outside temps? Normally people either use an A/C OR they exhaust the air, not both.

 

[Cannabean]

what he said ^^^

 

[MIway]

Read his thread... he shuts down his ventilation at lights off & kicks the deuy on at that time. So, he is sealing it at night... which is a big problem for his humidity.



The first two hours once the lights go out... actually, the first 30 minutes is the worst... the temps drop radically. Which forces the RH to shoot up... and if you shut down the ventilation... the moisture becomes trapped & your deuy isn't keeping up.

Where are you draining the deuy to? Hopefully out of the rooms...


I'd force vent the air outta there for the first hour or two + run a deuy + put an electric heater in there. Actually, the electric heater might be good enough w the air ventilation w/o a deuy... esp one of the less than 300 cheapo's units that aren't very efficient at removing water. But a cheapo 1500 watt ceramic heater goes a long way in addressing the RH spikes... and a preventative for mold...


Side note... ditch that 6" fan forcing air into the overall room... let it passively draw in... or use that other 6" as an evacuation fan on a scrubber for overall air exchange. Dunno why you are forcing air in there.

 

[guyyug]

and inside the tent a 20L dehumidifier i run only during the dark period. zero ventilation. only the passive intakes in the tent open, and air circulating.

It is going to depend GREATLY on the outside humidity. The inside and outside will eventually equalize with the tent open. If the outside has high humidity there is no way that you can keep it low. It will take a little work getting your tent sealed, I know, but it will be so worth it when you don't have to worry about it getting humid after a rain. Cold and heat snaps, just a constant environment. And if you do a good job of sealing the room, you can set a scrubber in the room constantly scrubbing and there will be little to no smell unless you get up to the door, that was the main fear for me, but it works.

 

[intotheunknown]

the reason im forcing the air into the room the tent is in is because the fan pulling the air out causes too much negative pressure and wants to suck the room shut. (self built room out of double layer panda plastic and framed in 2x4s). so the 6 incher is adding enough air to keep the negative pressure from being too strong and more so equaling it out. while still maintaining a good amount of negative pressure. the 6 incher also is a good lightproof powered intake. when the 6 incher runs during lights out the air is also being pushed out with 2 darkroom vents.

i am only running the air conditioner when i need to during the summertime towards the end of the 12 hrs when the fan cant keep the light cool enough.

the only thing i have not tried as of now is to run the air conditioner during dark period along with the dehuey.

i also have not tried to run a heater and the the ventilation system at the same time, but i think if i do i definitely wouldnt get my 10 degree temp difference between dark and light periods, and it would more so just suck the heat out and wouldnt reduce the humidity as much because it would be constantly exchanging the air.

but i do think that may be my solution, a/c and dehuey at the same time. zero air exchange. i have also thought about just getting some co2 and a sentinel or something and be done with it.

 

[intotheunknown]

i do not live in an area that has high humidity, nor is the house very humid. (roughly 50% ambient RH)

the tent in the dark period is at 60-69% with the air being exchanged 24/7. daytime RH runs at about 50% which isnt too bad.

 

[MIway]

^^ I'v done the first post before during the lights on... reduced air cooling the lights while running a deuy... forcing the a/c to cycle more to reduce the RH.

Prob I see at night is that you want to keep the temps up, so this will be dependent on the btu capacity of the a/c... a big one will actually overcool the room. But after the first hour... dunno... might not be an issue any longer.

As guy pointed out, this will depend a lot on the outside RH, but 50 is better than 69, so... And glad you have the negative air pressure bro... ;-)



The space heater is dry heat... and you could cycle the fans on a timer and/or speed control to dial in the total air exchange at lights off... to hit that sweet spot. Seems that you have all the pieces, just a matter of finding the right combo to dial in your room, within your overall climate conditions. Which you seem to be working through!



Check out the dif... day/night temp differential... rather than the conventional 10F cooler at night, this theory advocates for a rise in night temps of about 4~6F. Based on commercial crops like poinsettias... decreases internodal stretch.

There is also the rainforest theory... where so long as you maintain higher than 80F temps, then mold can't germinate... or has a very tough time, esp if you can keep a moderate control of RH.

Combine the two & run the rooms at 80F day... with 84-86F as soon as the lights drop... and an RH in the less than 50 range... no mold... and less stretch.

You will transpire a lot more watter, but... dialin it in is the name of the game.

 

[SneakySneaky]

what kinda media are you using for your plants, how often are you watering, and what kinda containers are they in?? start checking off the variables so you can identify the source of the high rh. seems to me that the airflow is sucking out the rh and that when the ventilation is off the water in your plants containers is filling up the room with rh from evaporization. the larger the size/quantity of plants the more your rh will rise from all that watering as well as the plants themselves. this is a head scratcher for sure.

 

[intotheunknown]

i do in fact know why i have high humidity, and there isnt much i can do about it.

i grow in an organic soil, water only. watering about every 3 days. currently in number 3 containers, about to get a final transplant into 5 gal buckets.

MIway, great info laid out. and you nailed it right on the head. a/c and dehuey run only during lights out and temps/humidity are in check. dialed in it is. good call man.