Evaporative cooler in vented room

Hey guys,

I just upgraded to a 1k from a 600 watt and temps are getting up to 86 in my 4 x 8 closet (only using half for the grow)

I have a Can fan hooked up with the carbon filter venting the room at about 190 cfm

I also have a 6" hurricane fan rated at 450 cfm hooked up the an air cooled hood totally separate from the grow space vents.

The intake for both of these is from an air conditioned room at about 68-70 degrees


Humidity is usually about 35% in the grow space and 86 degrees.

I was wondering if anybody has experience with an evaporative cooler in these kinds of conditions.

I found one for about 100 dollars that is rated at 150 cfm, so humidity should easily be vented by my 190 cfm exhaust. I am just getting confused as to whether these actually lower ambient temperature, or if it just feels like the temperature is lower.

I have a portable AC that I can repurpose but I will have to cut another hole in the wall so that I can keep the AC in a separate room. I just can't see getting another fan and filter to clean the stinky AC air. I'd have to get a humidifier in that case, too, as the rh is already too low.

Any advice/ideas/suggestions are welcome and appreciated!

Thanks,

Ziggaro said:

The intake for both of these is from an air conditioned room at about 68-70 degrees

Humidity is usually about 35% in the grow space and 86 degrees.

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That humidity is quite low. That means your incoming humidity is about 62%. The dewpoint is about 55 DegF. Very comfortable for humans, maybe a bit dry for plants.

Even if you could limit your temperature rise to 80 DegF, humidity would still be about 43%. Still low, but better.

Ziggaro said:

I found one for about 100 dollars that is rated at 150 cfm, so humidity should easily be vented by my 190 cfm exhaust. I am just getting confused as to whether these actually lower ambient temperature, or if it just feels like the temperature is lower.

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Well, I think you might have a bit of a problem. Evaporative coolers really do reduce the actual temperature of the room, so that's good. They pull heat from the room to do this. The trick will be to put this some place where it is (A) warm enough to evaporate an appreciable amount of water and (B) not so far away from the intake that you cool the exhaust but not the plants.

What I means is that you could put the EvapCooler in the exhaust stream. This would cool the exhaust air, but that really doesn't help your plants in the grow zone.

EvapCoolers that work will also use lots of water, so you would need some big reservoir of water or an autofilling valve like a toilet uses. It will work best if you warm the water with room air so it will be more likely to evaporate faster, which is what pulls the heat from the room and adds humidity. You could use something like a fish pump to bubble warm air from some place in the room through the evap cooler reservoir to warm the water, cool the air, and get a little bit more evaporative cooling. It might help, I'm not sure. The whole trick is to optimize things so you put maximum heat energy into the water.

If you are successful, the exit air from the evap cooler could be as low as the wetbulb temperature. For a combination of 86 DegF and 35%, the wet bulb temperature will be 66.7 DegF, not to far from your incoming air temperature. That is the theoretical limit of what you can achieve, I would feel good if you can get the air temperature down around 72 DegF from the Evap cooler. Still, it will really help.

After that, it's a question of how much you can optimize the system to evaporate the most water per day. One gallon of water evaporated per 12 hours is about the same as taking 100 watts off your light (more or less). That's just what the equations say, the trick is to figure out how to accomplish it in a way that is advantageous for plants.

If you have the space, you could try it. If there is no good place to put the cooler so that it can suck in warm air and push it out on the plants, don't bother. Cooling your exhaust is not helpful, you need to cool and humidify the canopy.

I think with your exhaust fan pulling out that fast, you won't really be able to increase your humidity from the evap cooler. It is pulling in fresh air faster than you can accumulate humidity.

It might work better if you were in some kind of enclosed space like an unused room or a crawlspace. This would tend to accumulate humidity that can be pulled in again and used. If you are truly pulling fresh air and exhausting it again, that won't help.

How much water do your plants drink in a day that gets evaporated? They are really good at this kind of thing, having been bred for millions of years to transpire water. If you have healthy plants, they will drink a ton of water and do the job for you.

-r2k

Isn't that way way too hot flower? As in you will get shit bud that is airy and weirded out?

Awesome thanks for the in-depth response. Intake comes from the closet door and the exhaust is in the top back corner. I'd be putting the cooler in front of the door blowing toward the plants. Sounds encouraging from what you say.

Yeah 86 is hot causes your bud to be less dense. Some buds will foxtail of that's what you mean. Cooler is coming tomorrow so ill update how that goes. Nowhere near flower atm just popped new seeds do no worries.

Thanks!

I always hate closet grows. All the cracks around the door generally lead to messed up airflow and light leaks. At least you have intake and outlet on opposing walls so the air flows through the zone and not just in one hole and out the other.

With that much airflow and wattage, I also wonder if your intake and outlet holes are big enough. Don't skimp on hole size, it is the cheapest way you will have to get better cooling.

I don't know if it is a good time, but what is the temp difference if you turn off the hood fan and block the intake/outlet holes for it? There are too many variables to analyze if you have two fans. If you turn off the hood fan and wait a few hours for temps to stabilize, we can separate the contribution of each fan. If I do the math right now with 1 Kwatt and 17 degrees rise, I get 185.9 CFM. That's just under your estimate of 190 CFM and could happen, but I really suspect it isn't. That would mean your hood fan is effectively doing nothing or almost nothing. I can't believe that, so that means you are losing a big chunk of your cooling power with the 190 CFM fan. Turn off the hood fan, let temps stabilize for a couple of hours, and report the temp difference.

I assume your hood fan is exhausting the air directly outside the closet. Is that true? Or are you blowing air from one side to the other without exhausting the hood? There isn't much good if the hood fan doesn't exhaust air to the outside of the closet.

Another thing, are you measuring the temperature at the canopy or at the air outlet? My formula works for sure if you measure the inlet and outlet air temps, other places don't give as accurate a viewpoint.

If you turn off fans, keep a close eye on your temps and judge if it is OK for your plants to get that level of heat. I don't want you to lose a crop for the sake of science. You could take the plants out of the grow zone temporarily if you want to make sure they aren't stressed from heat during this test.

-r2k

Move the ballast out of the grow space if you haven't already. Explore two stage cooling as discussed in the ventilation 101 thread. Insulating the reflector & ducting at the same time helps, too. Convective heat from the lamp envelope, reflector & ballast are significant, to say the least. Heat that never makes it into the grow space is not a problem.

It's the only thing I found workable in my space short of refrigerated air.

What's up guys!

Hey Jhhnn! I think I know what you mean from that thread.. been through there a few times. I am using 2-stage cooling now afaik. I have a separate fans and ducting for my hood and my space. The hood's air is completely separate from the grow. Ballast is also in a separate space altogether. The hood is a little warm so that is probably adding a couple of degrees. If there is a good option to insulate it, I will.

Back to the evap cooler though, I just wanted to report back on how the thing works.
Well, if you only need to cool a couple degrees its a small investment and doesn't use much power. It cooled my room down to 79 degrees (from 86 degrees) and brought the humidity up to 48-50.
Pretty much killed two birds with one stone for me
Just remember my rH started around 35-40 so if your rH is already 50 look for something else..

I had some of this leftover from another project, used it to insulate my reflector-

http://www.yourautotrim.com/thercarpad.html

Not exactly high R value but it helps.

I've come to the limits of what I can reasonably accomplish in my circumstances w/ 1000w & air cooling. It's not really as good in terms of temps as I'd like it to be so I approached the problem from the other direction, reducing heat output by going to two 315W philips CDM elite lamps & ballasts. This will be my first effort under those lamps. I'll report on the results over here-

https://www.icmag.com/ic/showthread.php?threadid=299165

New ballasts are expensive, but diligence paid off in a good deal for used ones.

Ziggaro said:

Well, if you only need to cool a couple degrees its a small investment and doesn't use much power. It cooled my room down to 79 degrees (from 86 degrees) and brought the humidity up to 48-50.
Pretty much killed two birds with one stone for me

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That's awesome! Instead of a 16 or 17 degree rise, you now have a 9 or 10 degree rise. That's about 40% of the heat that had before is now gone and you got some humidity benefit on top of that. Can't beat that kind of performance with a stick. I would say you are just about in the sweet spot for lighting, temperature, and humidity.

Keep an eye on how much water that thing consumes over a couple of lighting cycles. I'd like to know. I'm betting it is at least a couple quarts per day, probably more like 6 or 8 quarts. Does it have a reservoir to fill or is it plumbed into house water?

-r2k

r2k said:

That's awesome! Instead of a 16 or 17 degree rise, you now have a 9 or 10 degree rise. That's about 40% of the heat that had before is now gone and you got some humidity benefit on top of that. Can't beat that kind of performance with a stick. I would say you are just about in the sweet spot for lighting, temperature, and humidity.

Keep an eye on how much water that thing consumes over a couple of lighting cycles. I'd like to know. I'm betting it is at least a couple quarts per day, probably more like 6 or 8 quarts. Does it have a reservoir to fill or is it plumbed into house water?

-r2k

Click to expand...

That's what I'm thinking! And for 60 watts...

I fill this thing every day when lights come on and it's empty just before lights come off, so we're looking at about 2 gallons per day with 18 hours of light.

I don't have plumbing set up yet but it'd be as simple as running a small reservoir with a submersible pump on a timer and some 1/4 inch line to reduce the flow. I'm in there every day right now so It's no problem to go in there and fill it up once a day.

Jhnnn thanks for the link. That stuff is a little pricey, huh? If it will take me down a degree or two I'd consider it worth it, but as of now my hood only gets warm. Not hot by any means. What do you think?
Too bad you had to give up on the 1k.. I'm excited to see how it compares to the 600.

Ziggaro said:

I fill this thing every day when lights come on and it's empty just before lights come off, so we're looking at about 2 gallons per day with 18 hours of light.

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If it was me, I would set up a siphon. Much cheaper, no power, super reliable, and won't flood. Get one or more containers (like milk jugs) about the same height as your EvapCooler reservoir. Put the container(s) on a stand outside the grow zone and use some 1/4 inch drip irrigation tubing (really cheap) and submerge one end in the reservoir and the other in your container. Done!

The only trick is that you must fill the tubing with water before you submerge the ends. It's easy. Simply put one end in the container of water and use your mouth to suck on the other end until you get water in your mouth. Then, bend the tube somewhere to pinch the tubing and prevent water from running out. Take the tube out of your mouth and put it in the reservoir.

I have done this a bunch, and there is one more thing to make life easy with siphons. The drip tubing will curl and this makes it hard to keep the end on the bottom of each container. You can buy clear tubing for a fish tank from any pet store and it is the perfect size to slip inside the drip line. This gives you a nice stiff end that will plunge to the bottom of each container every time.

You will still have to fill up both reservoir and extra container every day, but it will always work as long as neither end is exposed to let air into the tubing. You can snake the tubing down, around, up and over as much as you want and it still works. Gravity does the work, and I can't remember a time when gravity failed due to power loss.

You won't get 100% of all water out of the container, but you can use about 95% of it. You can also add extra milk jugs to get more capacity. Just use a second drip line and another set of clear tubing to connect the second jug to dump into the first. You could add 9 or 10 more milk jugs this way. If you string enough jugs into the system, you could go away on vacation for a couple of days and not run out of water.

The other benefit you may find is that the water level in the jug outside the grow zone is exactly the same level as the water in our Evap cooler reservoir. You can watch the reservoir water level drop without opening the door by just looking at the milk jugs.

I have done this and know it works well. The only trick is to make sure you don't have air in the drip lines. This will almost surely cause the siphon to fail. Keep an eye on the water levels after you first install it and make sure water is moving out of the jug. No movement means the drip line has air.

-r2k

Look at this video.

Homemade Evap. Air Cooler! - The DIY "Planter Box" AC (air cooler) - up to 30F drop! - Easy Instr.

I had a large cooking tray filled with a large ice block that I made in it last night in front of a fan with the
air blowing into my cabinet. Once the ice melts, back in the freezer the tray will go. I'm only going to do
this ice thing on the hottest part of the day. Until I come up with something else.

News Update: LOL

But after watching that video I came up with this new idea. I just upgraded 5 minutes ago to using
a tiny 2 gallon aquarium as a water basin with a clean dish cloth hanging into it held by fishing line
with a tiny fan blowing onto it. Amazingly, my entire room has cooled off a couple of degrees.

The Kerala plants are being in the background enjoying their fresh air.