temp,dehumidifier question

[abnorml]

Hi all,

I just added a dehumidifier to the mix, and its pulling tons of water out of the air like it should. However, the temps have gone up 5-6 degrees at least up to about 85 degrees, and the night low is 78. I felt the output of the dehumidifier and it was like a heater. Is that normal? I thought it was more like an a/c than a heater.

thanks

 

[Guest]

Hi abnorml,

Good idea adding a dehumidifier to the mix, humidity is something that when controlled can be very beneficial to a gardener during different stages of growth. It is very normal for a dehumidifier to exhaust hotter air. You can vent this hotter air out of your growspace to avoid the increase in temps, or cool the space more accordingly to the newly added heat source.

Is there any way to mouth the dehumidifier in a way where the heat source will be on the other side of your growroom?


Remember the higher your temps, the higher relative humidity will be. The lower your temps, the lower your relative humidity will be. Given the same amount of water volume for each scenario.

Quick answer, vent that dehumidifier or set it up so that its exhaust is not in the growroom and no heat transfer can occur.

you run hydro or soil?

 

[abnorml]

Thanks for the reply Yat-Yat,

Its a recirc. dwc, with co2 using a tank. Have a 465cfm fan on the lights taking air from outside room and blowing outside. I just can't believe the humidity. It went up to 95% over night and only got down to 70% with lights on with no dehumidifier.

 

[stinkyattic]

Abnorml, it's quite similar to an a/c. But think of an a/c- the condensation is used for heat TRANSFER, and the pump itself does throw some heat. The trick is that with an a/c, the backside of it sticks out the window and simply lets that heat go into the atmosphere via the fine, thin metal grating which is designed to give maximum surface area for this transfer. With a dehumidifier, you have to exhaust the pump heat. I don't know how your dh unit is designed and whether there is some way to duct it, but a slight temperature increase is to be expected.
On the good side, you are now in range to be running your CO2- temps elevated 5-10'F are ideal.
So do I read correctly that your light cooling system is sealed off from the room itself? You are running a sealed-room style? A portable a/c unit that is exhausted correctly will solve both your humidity and heat problems, and controlling temperature swings will help get any water that gets into the air to STAY in the air.
Just some food fer thought.

 

[abnorml]

Thanks stinkyattic, I used to have a stinky attic, haha. If I vented the dehumidifier wouldn't that exhaust my co2 as well? And yes it is a sealed room, very sealed apparently. I'm not sure I follow the part about temp swings and keeping water in air. The temps are only dropping to 78ish lights off and get up to 85/86 with lights on.

 

[Guest]

Thanks for the reply Yat-Yat,

Its a recirc. dwc, with co2 using a tank. Have a 465cfm fan on the lights taking air from outside room and blowing outside. I just can't believe the humidity. It went up to 95% over night and only got down to 70% with lights on with no dehumidifier.

Are you exhausting only the lights right? Keeping it a sealed room otherwise? Do you have a/c pumping into the room? Do you run a water chiller?

What kind of air movement do you have going on in there? Do you have good circulation?

Sorry for all the questions, just trying to give some advice. Stinky is right about the port or window a/c, and honestly it may be the only answer short of venting your growspace. Recirc dwc holds a lot of water, and in a sealed environment can be quite the humidity problem. Keeping it cooler will help, not just with humidity but will also help the plants. Remember to keep rez temps < 74 deg.

I know you are worried about losing your c02, but with a system like this some will be lost. With proper air circulation your c02 loss can be minimal, just make sure your plants are using it before it falls. c02 is heavy, so stirring up the air really good helps use it better.

also a tip for advice, if you are going to use a port/window a/c and vent it outside like stinky attic pointed out. you have to make sure your scrubbing the air in the room so well that no smell will escape thru the a/c's exhaust. the same goes for the dehumidifier. as long as either one of them is contributing to the growspace, if it smells in the growspace then there will be smell in the exhaust from either or both a dehumidifier and a/c.

does your dehumidifier have a drain line or are you emptying the bucket?

do you use airstones in your dwc's? are your lids tight?

 

[stinkyattic]

Thanks stinkyattic, I used to have a stinky attic, haha. If I vented the dehumidifier wouldn't that exhaust my co2 as well?

That is a very very good point and I'm going to state again that I have no idea how your DH is set up so I'll use an AC as an example. A portable AC does use some room air to carry moisture and heat out the duct, unless it has 2 ducts. One thing my friend told me to try is making an INTAKE duct for your AC using cardboard, ducting, duct tape, and saran wrap hahahha. So in the same manner that you cool your LAMPS with air you don't care about, you also cool off your AC chiller coils!
Problem solved! I wish I had pics, but I never actually built one of these things on to my AC. Next summer I may. But by that time I'm certain you'll have got it sorted out, lol!

 

[globel]

dont vent you dehumidifier or dont use fresh at at its intake.. They work best like a scrubber... and they heat the air and hight them selfs in a closed room. One thing to remeber is In a encosed grow room if your using a sealed room... then drop the temp with your AC Less degrees less humidity.... if your sealed without an ac your dead. if your venting and the humidity is a factor. ( outside humidity high like florida or the south ) then slow down the vent. Air circulation is not as big of deal as people lead you to believe. Its the heat and humidity. PEPLE can live in a sealed grow room why cant a plant? I have not had co2 in sealed grow rooms designed for co2 and not had a issue. So Drop the temp the humidity drops too. DeHumidifiers work agents them selfs.

In the end weed grows in the winter and likes it cold.