Dehumidifier / Heat Problems

Hurdbird

Member
I am currently using a 45 pint black and decker dehumidifier inside my flower tent w/ (4) plants getting approximately (1) gallon each per watering. It pulls lots of humidity out and works wells but increases the temperatures in my tent up to mid to high 80's which I don't like. I currently have the dehumidifier controller set to 55%(Dehumidifier ON) and 45%(Dehumidifier OFF). The dehumidifier usually runs for like 2-3 minutes and raises temps 5-8 degrees before the compressor kicks on and while it does, continues to create heat. Once its running it brings the humidity down pretty quick but temps get high. Can I set this dehumidifier outside of the tent and duct in inlet from tent to the dehumidifier and keep exhaust outside the tent? This would help alleviate all of my heat problems.

https://www.amazon.com/gp/product/B01DLPUWKI/ref=oh_aui_detailpage_o03_s02?ie=UTF8&psc=1
 

BobCajun

Well-Known Member
Exactly the problem, dehumidifiers vent the hot air from the compressor right into the same space, which is why I never use them. Hot enough now. What you actually need is an AC with the cold part separated from the compressor part by a hose, it's called a split AC. The cold part, which you put in the grow space, will condense water from the air just like a dehumidifier but with the heat outside. I never owned one myself, just use a regular window AC which works the same way, water drips outside, so I don't know how they are designed to deal with the condensation. I guess there must be some kind of drain on them.
 

nevergoodenuf

Well-Known Member
Do you have an exhaust fan on your tent. If you do it doesn't seem to be big enough. You could run the dehumidifier in the room and just increase air flow in and out of the tent.
 

Hurdbird

Member
Exactly the problem, dehumidifiers vent the hot air from the compressor right into the same space, which is why I never use them. Hot enough now. What you actually need is an AC with the cold part separated from the compressor part by a hose, it's called a split AC. The cold part, which you put in the grow space, will condense water from the air just like a dehumidifier but with the heat outside. I never owned one myself, just use a regular window AC which works the same way, water drips outside, so I don't know how they are designed to deal with the condensation. I guess there must be some kind of drain on them.
I do HVAC for a living but a mini split is overkill for a 5' x 5' tent. I'm considering venting the exhaust side of the dehumidifier outside the tent. Has anyone ever done this? May not be good for the dehumidifier but would definitely solve my problem with the added heat but would be exhausting additional CO2 as well. I currently have my dehumidifier set for 55% and a 440 CFM exhaust fan (set about 1/2 speed) running for 3 mins every 12 mins.
 

chemphlegm

Well-Known Member
additional c02? you also add c02 to the tent?
the room exhausted to will warm also, eventually maybe equalizing the temp between tent and room, then what?
why not run that 440 fan full time?
 

BobCajun

Well-Known Member
I do HVAC for a living but a mini split is overkill for a 5' x 5' tent. I'm considering venting the exhaust side of the dehumidifier outside the tent. Has anyone ever done this? May not be good for the dehumidifier but would definitely solve my problem with the added heat but would be exhausting additional CO2 as well. I currently have my dehumidifier set for 55% and a 440 CFM exhaust fan (set about 1/2 speed) running for 3 mins every 12 mins.
The exhaust from a dehumidifier is the dried air. You'd be putting the dried air out into the main room. They don't have a separate heat exhaust, that's the whole problem. You can't get the dried air without the heat, unless you have a cooler for it. Might as well just put a regular exhaust fan in the tent as do what you suggested. I suppose it would prevent the main room from getting humid. If you're pulling air from the room through the tent then that air would be drier going in than usual. It would be the same as just putting the dehum in the room, completely outside the tent.

You mentioned CO2. That's the source of your trouble right there. No way to keep CO2 in and not have it closed off, which results in humidity and heat buildup. When you ditch the CO2 your life will improve dramatically. You may get up to 30% faster growth and somewhat higher yield but at the expense of screwing up everything else. Is it worth it? You decide. If it was, you probably wouldn't be here asking for help right now.
 
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Hurdbird

Member
Decisions, decisions... the flower tent gets up to about 85 degrees worst case right now. If I removed CO2 and ran exhaust fan more, I could easily keep it to 70-79 where I want it with lower humidity. When adding CO2, can't you get away with higher temps (mid 80's) without doing any harm? Plants look nice / happy in week 3 of flower with these conditions currently. Thanks for everyone's help!
 

chemphlegm

Well-Known Member
whoa grasshopper.

how are you augmenting your tent with c02?
what are you using to control the augmentation?
yes, during high temps plant will suffer first because of higher metabolism requiring more c02 and will become their first lacking resource if not provided for them.


But, high temps require conditioned air, a better grasp on the environment, not more c02. c02 is used after every other resource has been generously provided.
 

Daveindiego

Well-Known Member
I am currently using a 45 pint black and decker dehumidifier inside my flower tent w/ (4) plants getting approximately (1) gallon each per watering. It pulls lots of humidity out and works wells but increases the temperatures in my tent up to mid to high 80's which I don't like. I currently have the dehumidifier controller set to 55%(Dehumidifier ON) and 45%(Dehumidifier OFF). The dehumidifier usually runs for like 2-3 minutes and raises temps 5-8 degrees before the compressor kicks on and while it does, continues to create heat. Once its running it brings the humidity down pretty quick but temps get high. Can I set this dehumidifier outside of the tent and duct in inlet from tent to the dehumidifier and keep exhaust outside the tent? This would help alleviate all of my heat problems.

https://www.amazon.com/gp/product/B01DLPUWKI/ref=oh_aui_detailpage_o03_s02?ie=UTF8&psc=1
Yes, you can run a dehumidifier out of the space, and use ducting into what you want dehumidified.
 
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