Controlling humidity without raising temperature

[HueJass]

Is it possible? I have been battling humidity for the last few years and using a dehumidifier is like a double edged sword because it adds a good 5 degrees to my ambient temp. On a bad day my temps are in the mid 80's with lights on, and generally don't fall much below 80 with the lights off. If I run my unit with the lights on I could push 90 many days.

I see some folks don't run their dehumidifiers during lights on and instead use them during the dark period. I am not sure this will cut it for some of the strains I am running, I'm almost positive I would see mold from this. My dehumidifier works pretty well, but has problems keeping things below 45% in the summer - 50% on a bad day. It also has problems on extremely wet, rainy days.

My portable 12kbtu a/c doesn't really do much cuz there is too long a distance to run the exhaust so the heat gets backed up after a while and the unit doesn't produce much cool air.

My exhaust is hooked up to my lights so naturally I am losing some of the dry air that I am trying to produce via running the dehumidifier. I guess I don't get how you achieve proper balance with indoor environments.

Some questions for you...

How are you guys removing moisture from the air without adding heat? Further, how are you maintaining dry air in your space while removing heat via exhaust?

Someone please enlighten me on dialing in my environment.

 

[Pakrat]

You’ll need to either vent the dehumidifier or the AC to the outside world. AC provides the best of both worlds in my opinion, if you’re dealing with high RO. I found a thread here that explained how to vent a window AC and it’s working great for me. I’m sure you could use the same principles for a dehumidifier. What humidity are you targeting?

 

[HueJass]

I'd like to go as low as possible, but probably say 50% would be realistic. I agree on the ac, but I currently only have access to the 12k portable - if I want to use the portable I think one option may be an inline fan to help with the exhaust cuz it needs to travel 15ft. Like the cheap ones you see at HD, they're like 20$, but I'd have to do the wiring I think. That may help my prob of having the heat back up in the exhaust though. If I use the ac I also have to worry about filtering the stink out of the exhaust which is a sizable complication for me as I filter my lights before I exhaust them currently.

If I use the dehumidifier and vent to the outside world won't I be losing the dry air I am trying to achieve in the room?

 

[MIway]

You could try hooking up a brand new fan/scrubber combo to push the air cooled lights, taking the a/c off that system. Let the a/c work the room, getting the added moisture removal + immediate cooling. This combo of events will make a mark on the rh levels... esp if you can keep a steady 80~84F.

Stepping up into one of the Thermastor lines will make a big difference in total water removal + add back heat, but that would be a good 4x the cost of the options from above.

Other than that, it is exactly what you are doing... dialing it in. Just takes a lot more than the words on a page lead you to originally believe... read, it's easier said than done. ;-)


EDIT... and put a 6" inline on the portable a/c... will definitely help with the overall heat exchange over long runs... and insulate the outflow.

 

[Pakrat]

You can vent the AC out of the structure and it will run more efficiently. Keep in mind for all the hot air you suck out, you need a cool air return. You might not find a powerful enough fan at the depot, Amazon is good or your local grow shop.

I found this thread helpful: https://www.icmag.com/ic/showthread.php?t=95491

 

[HueJass]

You could try hooking up a brand new fan/scrubber combo to push the air cooled lights, taking the a/c off that system. Let the a/c work the room, getting the added moisture removal + immediate cooling. This combo of events will make a mark on the rh levels... esp if you can keep a steady 80~84F.

Stepping up into one of the Thermastor lines will make a big difference in total water removal + add back heat, but that would be a good 4x the cost of the options from above.

Other than that, it is exactly what you are doing... dialing it in. Just takes a lot more than the words on a page lead you to originally believe... read, it's easier said than done. ;-)


EDIT... and put a 6" inline on the portable a/c... will definitely help with the overall heat exchange over long runs... and insulate the outflow.

I actually was just reading a thread where you made some comments about raising your temp during lights out 5 degrees to the point where mold could not live. I thought that was pretty interesting stuff and something I actually took some time to consider. The problem is that I hang out a lot in my room it would make hanging there not so fun with a space heater running in the summer. Do you have any other print/link suggestions where I could read more about this?

I've also considered adding CO2, but need to do some serious sealing before I could make the commitment. But, it would allow me to run at 85 comfortably, boosting yield at the same time. I might even be able to remove the lenses from my lights cuz I am at 80 ambient on a good day.

I do like the sound of the 6 inch for the ac, that might be my only option. I'm week 3 of my cycle so have to start worrying about bringing my rh down from the high 60's to the high 40's. I will need to use the dehumidifier as well to accomplish that, even when I had the ac properly hooked up it barely puts a dent in my rh levels. But like I was saying the dehumidifier adds so much heat that I hate to run it with the lights on, but don't have much choice. It does make CO2 more appealing cuz i push a good 85 with the unit running.

 

[HueJass]

You can vent the AC out of the structure and it will run more efficiently. Keep in mind for all the hot air you suck out, you need a cool air return. You might not find a powerful enough fan at the depot, Amazon is good or your local grow shop.

I found this thread helpful: https://www.icmag.com/ic/showthread.php?t=95491

Thanks for the link and info Pakrat. I use a passive intake at this point for fresh air cuz my room is not sealed real well at all. Gonna look to add a fan to my ac exhaust for sure and get that heat out of there.

I have also considered venting both my lights and and room to a another room - a lung I guess it's called - and then filter that air to outside. Sounds good in theory, but would require some rigging.

 

[budleydoright]

This is a very dynamic situation, right when you nail this down your seasons change and it's a whole new ballgame! You just have to dial it in. If my AC isn't removing enough moisture during the photoperiod, I allow my lights to put more heat in the room, which causes my AC to run more and dehumidify. I then set my dehuey just below where I want my ac to maintain. Then when the lights go out the dehuey handles it. If it generated too much heat then the AC kicks back on and the RH is handled even faster. In the winter though it's a different set of rules. ambiebt air is cooler, AC doesn't need to run as much. Dehuey does almost all of the work during the photoperiod and at night.

Set a goal for your temps and RH and then tweak till you get there. I had to watercool my dehuey to get the heat down this summer, not needed last year.

 

[HueJass]

Hey budley, so when you watercool then you have zero heat coming off the unit and just dry air? Pass along some info/links if you have it. Sounds interesting.

 

[thefatman]

Water cooling and dehumidification.

A good system that dehumidifies a sealed room as well as coolng can be made using a water chiller and a few iceboxs or I use these from eBay ( http://cgi.ebay.com/OUTDOOR-WOODBUR...242?pt=LH_DefaultDomain_0&hash=item19c785023a ) or here is one sold cheaper ( http://cgi.ebay.com/Lytron-Radiator...085?pt=LH_DefaultDomain_0&hash=item3a68852f85 ).They sweat (dehumidify) at all times there is cold water running through them and there is moist air hotter than the water in the grow room. I run cold water through them at all times for dehumidification and have the fans controlled by a thermostat so as to cool the room as needed. There is no heat added to the room and the heat from the fans when they are running as the fans heat is taken up by the cold water running through the heat exchanger. Iceboxs come with a plastic box around them so the water that condenses is caught by the plastic box so as to be drained with a tube. You would have to put a catch pan under the heat exchangers I linked to on eBay to drain away the water that condenses on the heat exchanger. Just think of how water condense on a glass filled with ice water when the room air is hot and moist. The same principle but it also provides cooling when needed. Here they are sold by a retailer without the fan for over $700 each. The fans sell retail for about $100, discount houses or eBay get about $65 for the Tarzan fan used. How many would be needed depends upon how much time your 12,00b Btu fan runs per hour when working properly. You can get bigger heat exchangers on eBay if you need to remove a lot of Btu's of heat. For an example, if your air conditioner only runs 15 minutes per hour then it is extracting about 3,000 Btu, per hour. That means for the same amount of Btu's to be extracted by the heat extractors linked to it would take two of them. The fans would only run when heat need to be removed so they would run no more then the air conditioner was running as they will still extract some heat even when the fans are not running. With a larger heat exchanger such as this you can extract heat as fast as your chiller can produce cold water to be circulated through the heat exchanger. Of course you would need more than one 6" fan blowing air through the heat exchanger but either would extract heat and dehumidify just like an air conditioner does. The chiller could be placed anywhere reasonable as long as you insulated the pipe feed water from the chiller to the heat exchanger. This system would work great also when using CO2 in a sealed room as no air would exchange between in side and outside of the room.

 

[HueJass]

Damn fatman, thanks for the explanation, I think I get it. How much might I be looking at to put a system like this together though?

 

[thefatman]

Damn fatman, thanks for the explanation, I think I get it. How much might I be looking at to put a system like this together though?

Probably about $300 to $500 will cover everything but the chiller. The chiller price will run from about $425 for a 1/4 hp chiller up to about $825 for a 1 hp chiller. The size would depend mainly on the wattage of your lights and if you are also cooling the light with anything like outside air through cool tubes or enclosed hoods. Another major heat adder is if you have the lighting ballasts, and pumps inside your grow room. Whether the grow room is insulated and the ambient temperature where the room is located are also is large factors to in considering the size of the chiller you need.

Basically there can be a large difference in costs for both the heat exchangers and the chiller depending on the Btu capacity needed.

 

[budleydoright]

Hey budley, so when you watercool then you have zero heat coming off the unit and just dry air? Pass along some info/links if you have it. Sounds interesting.

I just took an extra heat exchanger and hung it off the back of my dehuey. It doesn't absorb all of the heat but it does put a nice dent into it and help keep my system from chasing it's tail!

I've built most everything myself and am constantly trying to improve it. Ideally, it will evolve into what fatman has described here and on other posts

I'm currently using an 8kbtu AC to keep the room cool, a 60 pint dehuey, 3 fresca sols with a converted 6kbtu window AC chiller. My insulated box sits in an attik like space with 95-110 degree ambient temps. I'm debating on water cooling my airconditioner, or building a bigger chiller and air handler for the room once I expand into it's permanent size.

 

[HueJass]

sounds like a well thought out system. frescsa sols, first I heard of those, they look pretty cool. if I understand it correctly the chiller chills the water that cools the fresca so you don't need to run an exhaust that will suck out your co2. pretty smart stuff.

 

[budleydoright]

I see some folks don't run their dehumidifiers during lights on and instead use them during the dark period. I am not sure this will cut it for some of the strains I am running, I'm almost positive I would see mold from this. My dehumidifier works pretty well, but has problems keeping things below 45% in the summer - 50% on a bad day. It also has problems on extremely wet, rainy days.
Someone please enlighten me on dialing in my environment.

What are you measuring your RH with? I have 3 devices in my room and all 3 will read different unless we're into 60+ then they all kind of agree. In the 50's and 40s they're all over the place.

I'm going to bite the bullet and buy a real instrument soon as I understand these things have a very narrow range of accuracy.

 

[HueJass]

What are you measuring your RH with? I have 3 devices in my room and all 3 will read different unless we're into 60+ then they all kind of agree. In the 50's and 40s they're all over the place.

I'm going to bite the bullet and buy a real instrument soon as I understand these things have a very narrow range of accuracy.

I use one device, and it seems somewhat accurate although it's a cheapy from walmart. it's usually within 5% of what the weather forecast is and I'm in a basement so you gotta expect rh to be a bit higher because of that alone. when you say real what do you mean? mine shows the min, the max, and current.

I took a good 2 gallons out of my spaces air last night as I ran the unit all night to the point that the container got full. I usually have a hose hooked up that runs into a bucket so I don't have to empty the container so much. According to my gauge I got down to 54% last night before it got full. That's not low enough for what I am running. Im starting week 4 bloom so it is to the point where I have to start being concerned more or I am going to lose quite a bit to rot.

 

[budleydoright]

Hygrometers have a fairley narrow window of accuracy. If the device is calibrated at 80% then it will be the most accurate in that range. I understand that they can be way off when they are outside of their range. So you may want to get a couple of different units and get a sense for the average. If I went off my cheapy alone I would be in the dark most of the time! So I have a cheap analog, a cheap digital hi lo, my room controller as well as my dehuey. They can be as much as 15points apart.