Sealed room dehumidifiers?

[TwistedPistil]

Having a go at several sealed room designs, and really want to know what people's personal experiences are with sizing dehumidifiers for sealed rooms. I know it's based off water consumption. I am dreading pricing these things for a 10x10 ft space. 3500 for a dehumidifier to take out 25 gallons a day? Oh boy.
I'm also going to be attempting to increase the EC in relativity to PPFD, co2, and water uptake, all in step with each other in an attempt to really push the plants,, and I'm curious what kind of water consumption people have been able to drive their plants to, per light, or Sq ft, or 5x5 or whatever.

how much water can be used by cannabis per100sq ft of canopy, or what kind of low and high end numbers are there, if any, for sizing these things other than hindsight such as "its how much water you're going to use".

any data, even anecdotal accolades would be appreciated.

 

[troutman]

I just set mine up a few days ago cause humidity spikes when the lights goes out on the days I water
and the windows are closed since it's Winter here now. Mine has a built-in humidistat and can be set
from 35-85% humidity. I got the small 22 pint version. They do have larger models up to 70 pint.
There's a hose attachment at the back of it that I can hook up a garden hose so I don't have to
empty it manually if I wanted. It has a built-in timer as well so you can set it in 1/2 hour increments
to 24 hours or set it to run continuously. You can also set it on high, medium or low speed. I'm in
flowering now and set it to 55%. I'm using a 10' X 5' grow tent and it controls the humidity no problem.

Shop around, I'm sure there's many kinds that do similar things as mine.

This is the one I got and I purchased it at Lowes at $299 CDN + tax and really like it.

https://www.frigidaire.ca/Home-Comfo...tate=pg:2/ct:r

 

[TychoMonolyth]

The plants will transpire about 80% of the water you use. So do the math. You won't be watering 30 gallons a day in 100 square foot room. If you are, then it certainly won't cost you 3500 for a unit.

Here's a list. Take your pick. I wouldn't pay more than 1k.
https://www.globalindustrial.com/sea...q=dehumidifier

 

[f-e]

Yesterday, in early bloom, mine drank 7.5L per meter. This has approached 10L before, and I reckon I could go further once I'm dialed in better.

This was 5L while the lights were on, so a 10L dehu would just cover it. A unit that can do 10L at 60% is usually sold as a 20L or 5 gallon in old money. Quick finger count, you need a 70gpd unit.

Look at EC motor variants. They are just trickling through. They might consume 3000w instead of 4500w. They also offer variable fan speed, automated such that it varies the units capacity within a small range. This can keep them running. If instead it's cycling on/off them there is usually a delay before restart, without which the unit wouldn't last long. This delay of 15-30 minutes isn't suited to a sealed space producing so much moisture. If you have to use the most historically typical machines, you really want at least two. One that can't cover the job, so runs continuously. One that cycles. So you are never totally without dehu capacity.

 

[TwistedPistil]

Yesterday, in early bloom, mine drank 7.5L per meter. This has approached 10L before, and I reckon I could go further once I'm dialed in better.

This was 5L while the lights were on, so a 10L dehu would just cover it. A unit that can do 10L at 60% is usually sold as a 20L or 5 gallon in old money. Quick finger count, you need a 70gpd unit.

Look at EC motor variants. They are just trickling through. They might consume 3000w instead of 4500w. They also offer variable fan speed, automated such that it varies the units capacity within a small range. This can keep them running. If instead it's cycling on/off them there is usually a delay before restart, without which the unit wouldn't last long. This delay of 15-30 minutes isn't suited to a sealed space producing so much moisture. If you have to use the most historically typical machines, you really want at least two. One that can't cover the job, so runs continuously. One that cycles. So you are never totally without dehu capacity.

Thank you everyone for the reply. f-e, thanks for the detail on that L/m2. Around 8-10L/meter² is right around what I'm sizing it for. 10L/meter is about 26.5gal per 100sq ft. 2 105 pint models is 26.5 gallons.

I got a killer deal on two used quest 105 models. I'm going to run one independently on a setting and fan speed that won't keep up with the room during the fastest periods of water consumption and the other one I will hook up to my environment controller. I don't physically have the dehumidifiers yet, I'm getting them from a friend, so I'm not sure what they're capable of as far as timers and fan speeds and such. If I need more down the road, I will consider it a blessing because my plants will be drinking a ton of water. But for the price I couldn't realistically not buy them both. Both running is 26 gallons per day, and I think that's a good initial goal for a consumption level.

 

[TwistedPistil]

Again, thank you for the advice, ideas and reference points

 

[f-e]

Remember, most dehu's will reach there rated capacity, only with 100% RH and elevated temps. Their function is cooling the air, to get condensation. The hotter the air, the more they can cool it. Also the damper the air, the more they can get out.

I'm looking at a new one. It's 25L per day. It will do 12L per day at 25c and 60% RH. To reach 25L per day, It needs to be in a 30c room at 80%.
It's the new breed of EC motor units, which better the typical designs. My current unit is a 20L and at 22c and 50% RH is can barely make a drip. Though it can do 20L a day at that same 30c 80%.
My unit in use takes 440w and the new one tops out at 270w but has been seen using much much less in independent testing.
They got new stock last week, and it sold out in days. Looking at that 440 vs 270 you should consider the lighting load at 300w. For that is what they can cover. I don't know what the quest is, but your job kinda demands a split system. Like goes in duct work, or ceiling cassettes. Otherwise most of the heat in your room will be from dehumidifiers. Back to the number, my 300w of light, is 200w of heat, and 440w of dehu is all heat. It's very disproportionate. The split system would offer you some cooling for your lighting load, not a lot of excess heat.

 

[TwistedPistil]

Remember, most dehu's will reach there rated capacity, only with 100% RH and elevated temps. Their function is cooling the air, to get condensation. The hotter the air, the more they can cool it. Also the damper the air, the more they can get out.

I'm looking at a new one. It's 25L per day. It will do 12L per day at 25c and 60% RH. To reach 25L per day, It needs to be in a 30c room at 80%.
It's the new breed of EC motor units, which better the typical designs. My current unit is a 20L and at 22c and 50% RH is can barely make a drip. Though it can do 20L a day at that same 30c 80%.
My unit in use takes 440w and the new one tops out at 270w but has been seen using much much less in independent testing.
They got new stock last week, and it sold out in days. Looking at that 440 vs 270 you should consider the lighting load at 300w. For that is what they can cover. I don't know what the quest is, but your job kinda demands a split system. Like goes in duct work, or ceiling cassettes. Otherwise most of the heat in your room will be from dehumidifiers. Back to the number, my 300w of light, is 200w of heat, and 440w of dehu is all heat. It's very disproportionate. The split system would offer you some cooling for your lighting load, not a lot of excess heat.

Thank you very much for the advise sir. I appreciate it. This room will be 4 985w LED lights. I'm in the process of sizing Dehumidifiers for the room, adding those BTUs to the BTUs for the lights and other electronics in the room, then sizing the appropriate sized AC/heat pump last. I will leave headway for another dehumidifier to be hooked up. I know the AC will help, and I will measure that condensate to the best I can.

I am going to catch the condensation from all of my dehumidifiers and measure what they actually are taking out and use a condensate pump to catch and fill a reservoir. This way I can measure their capacity in the room's environmental condition as opposed to manufacturers lables.

I'm proactively looking for used Quest dehumidifiers due to their efficiency per Amp along with a good amount of data of using them with cannabis grows. Around Denver, there are plenty of used Quests, so for the prices I'm seeing, I can't in good conscience say no.

I got those two Quest units for 500 each, from a friend, used. But I know they work. The sizing just happened to come out to that number of 26.5gallons, which is perfect for this 10L/m².
I will get a third unit, probably even proactively get it mounted and ready to go to work just in case.. I will do my best to measure the water these two units are capable of taking out of the room, and if they get to the point of overworked, I'll make some notes about what they actually drew vs what they are rated for. I understand they'll draw less than they would at 80%rh.

We are planning a 12 light room, and this will eventually become a veg room merely by changing the lights out with a more efficient but less powerful model LED. It's our beta "figure out all the shit we need to know before building out the big room" room.

I really appreciate all of the advise. Unlike a lot of growers, I really like to learn and accept that other people often do certain things much better than I am capable of. I humbly accept all pointers, advise and constructive criticism.

The best grows I've had were when the "things to watch out for" lists had all been thoroughly examined. So thanks for helping me add and check off things on that list.

 

[f-e]

No problem buddy. I'm pretty good with kit and environment, which is why my plants usually do well. However, when things do go wrong, I'm sure you will be there with advice.

 

[f-e]

TwistedPistil
Did you figure it all out?
Water gain from the plants, the heat gain from the equipment and the de-humidification from the AC and dehu's ?

 

[flylowgethigh]

On a smaller scale, I am looking at one of those room AC units that blows the heat out through a hose like a dryer. Biggest issue with the dehuey is the heat it makes.

 

[StickyBandit]

So how often does the air need replacing in the room to be sure of adequate CO2 availability or what is the preferred method ?
We have high heat and humidity here in Auckland, New Zealand atm and I have a portable AC I can set up that blows the heat out a hose and cools and controls humidity in the room. I guess it would be best to recirculate the cool dry air as long as possible before replacing the air ?

 

[Switcher56]

I took a different approach... Running a dehuey from the inside rises ambient air temp 6-8 degrees. It was a problem with my set up (unwanted heat) I use to run a contraption like this...



It sucked from the top, went through the dehuey and discharged through a charcoal filter (top on tent right side). When that unit bit the dust, I simply installed an inline fan in the outlet, operated by my humidity controller, and discharges via a charcoal filter. Works like a charm and big cost savings. Mind you this is a small set up.

That being said, from what I have gathered (read) a lot of commercial greenhouses either have vents or an exhaust fan operate when RH gets to high. So basically I am running a "mini" exhaust fan.



In summation, the analogy is why dehuey a space and increase room temp, in the process, only to have to run an AC to keep the room at a constant temp $$$. The whole idea of de-humidification is to get rid of excess humidity, not increase ambient temp in the process.