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ac vs dehumidifier

oldjarhead100

oldjarhead100

New member
My bloom rooms RH is way to high so I need to get either a small ac unit or a dehumidifier . I cant decide witch one would be better so I.m throwing it out there
 
With just running an air conditioner my rh stays about half what it is outside. We average 80plus humidity here in the summer but inside stays about 57% or lower. Not sure if that helps any.
 
My rh went from 80% to 56% in two days with the addition of a 3.5 litre dehumidifier. Temperature rarely goes above 80°F so, I think I'm ok. An ac will bring rh down some but I'm not sure how much.
 
What temps are you running at?

Using an A/C can be a mess, as it lowers the temperature which in turn will increase RH and may not drain the water/moisture away from the grow or intake.
That said, if you vent the intake & exhaust and the condensation, out of the room it could work.

I have central air so that is all taken care of- and I will use an A/C - only "IF" my grow tent temps get too high, LED's can run at higher temps (mid 80's) which inturn helps with rh.
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Otherwise, I have been able to use a extreme defoliation along with increased ventilation.
 
I'm not sure what kind of a/c you're referring to that raises humidity. Every one I've seen pulls warm, moist air OUT of the room, blows it over cooling coils & drains condensate to the outside. While not its primary function, some degree of dehumidification is a byproduct of this exchange of air. That is, at least to my understanding. I could be mistaken.
 
Morning OJH, @WeedPharma, has got your answer, Try your best to keep the temps down, but extreme defoliation, really helps with lowering your humidity.
You don't have to defoliate, only on the third week of flower, I take leaves off my plants daily. But everyone does things differently.
I'm sure you will get your problem taken care of. You always do.:p
 
I do think a dehumidifier will cost less to run than an air conditioner. So if room temps do not get hot maybe the dehumidifier would be better. But i could be wrong.
 
My step dad is a lineman, I asked him which is more efficient: a/c running on 110v or 220v. Without getting too specific, 220v.

I asked a friend who opened a grow shop that has been growing for quite a while it my area, what portable ac he is running. He advised to go with a commercial unit. It doesn't cost that much more and lasts much longer. The unit I was looking at had a 75qt dehumidifier or could be plumbed to drain.

Oldjarhead100 if you like I can get the name and model number tomorrow. It wasn't 220v but 14,000btu is more than double what I need, so hopefully it doesn't have to work too hard.
Hope this helps decide.
 
Redwasp said:
I do think a dehumidifier will cost less to run than an air conditioner. So if room temps do not get hot maybe the dehumidifier would be better. But i could be wrong.
Click to expand...

Depending on the size of unit, dehumidifier is slightly less. Not enough to warrent concern. Both are ac systems.
 
Thanks all for the ideas The room is 6 feet by ten feet so thats not very big ,I built the room last June/July so I have no idea what is going to Happen. I was thinking and that takes me a long time lol
 
Hello everyone - First post, Just thought I'd add my 2 cents being a retired electrician with an HVAC license.

First, an oversized AC will not do very well at dehumidifying as it will reach temperature setpoint and shut off before dropping humidity to an acceptable level. It will then short-cycle on temperature turning on/off too many times an hour to be efficient.

Even the smallest of window units (5000btu) will have this problem in a small room if trying to keep temps in the high 70's. My grow room is 10'x10' and cannot drop the humidity to 60% unless I also drop the temp to 68F, so I bought the smallest "real" dehumidifier I could find ($110) now I can keep perfect temp/humidity levels. Keep in mind that a dehumidifier will also raise the room temperature so I have to run them both to get the perfect balance.

Also, there is no appreciable power usage difference between 120v or 240v air conditioners as it is the total watts that count and not the voltage. The reason they go with 240v is because of outlet amperage and wire sizing, the typical 120 volt 15 amp outlets can only be loaded to 1500 watts which would be around a 12,000 btu A/C. Also, a small dehumidifier can use 1/3rd the power of a small room AC - 150 watts vs 500 watts.
 
I have an ac that also is a dehumidifier. But the dehumidifier won't help with high temps in my grow area. What are your temps like? Cooler air will hold onto moisture. When my grow room is at 65-70f my humidity goes 50+% but when it reaches 75-80f it drops below 50%. Not sure what kind of exhaust you're running but good air flow would help even with high rh. Seen some growers sitting at tropical conditions and still do well. If it's too hot ac, if heat isn't an issue dh. Or a unit like mine that does both.
 
The difference you see is the "relative" part of RH, where warmer air can hold more water by volume, in your example an RH of 50% at 70F holds 7.8 grams of water while an RH of 50% at 80F holds 11.3 grams of water which is 3.5 grams or 40% more than the 70F air - 80F at 34% RH is the same as 70F at 50% RH.
 
Also to add, ensure it is vented outside of the room you are tring to cool. Removal of heat to where it makes little to no difference.
An oversized unit will also cause short cycling and will cost you more in electricity and repairs ;)

Hy, thank you thats ehat I was trying to say. Also an HVAC card holder, along with my HRAI heat loss / heat gain. You definitly have more knowlage than I!
 
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