New CEA Room build questions

[timmur]

So I’m getting ready to put together a CEA room and was looking for some feedback and answers to a few questions.

The CEA room is going to be a room within a room though not really a full-on lung room. The actual grow room is an insulated modular design and will be 8 x 10 x 8 ½ (W x L x H) with full climate control. The room that contains the grow room will be a normally heated and cooled area with no other environmental controls in place. Its size is 11 x 14 x 9 (W x L x H). Don’t ask why I’m not building out the whole room!

The design goal of the room is to maximize yield per square foot and quality (potency and essential oil content). To meet these goals, I’m going to use CMH lighting for both vegetative growth and flowering. To get maximum uniformity I’m going with Cycloptics Greenbeams mounted permanently on ceiling and Orca on the walls.

To shorten cycles further than what the Greenbeams can do, I’m going to use far red lights. My hope is that I can shave at least one week off a cycle and maybe two on some strains.

To get the fastest vegetative growth, I’m going with Current Culture’s RDWC system and augmenting with CO2.

Finally, I plan on growing mostly 100% sativas (Ace, Cannabiogen, Mandela, etc…) so I’ll be looking to keep these plants as short as possible. To minimize stretch I plan on doing "the morning dip" (or cool morning pulse) and mechanical induced stress (probably fans turned up on high).

Partial Equipment List
14 Cycloptics Greenbeams 315w Ceramic MH
10 Watt Far Red Light
UCE9XL
½ hp chiller
100-gallon top off res
24k mini split (Brand?)
Dehumidifier – 100 pint?
Hydrofogger humidifier?
Hyper Fan Stealth 10 in 1065 CFM/Air Box 4 Stealth Edition 2000 CFM 10in Flanges
AgrowTek GC-Pro Control System


Questions:
Is the mini-split sized right and what’s the best brand (inverter type)?
Is the dehumidifier sized right?
Do I need a humidifier and if so is the hydrofogger good, overkill or?
Fan and Airbox for recirculating scrubber. Size ok on these?
Would it be good to bring in room air (HEPA filtered) to provide slight positive pressure to room?
Anything else I'm missing?
Thanks in advance for any input!

 

[queequeg152]

Questions:
Is the mini-split sized right and what’s the best brand (inverter type)?
Is the dehumidifier sized right?
Do I need a humidifier and if so is the hydrofogger good, overkill or?
Fan and Airbox for recirculating scrubber. Size ok on these?
Would it be good to bring in room air (HEPA filtered) to provide slight positive pressure to room?
Anything else I'm missing?
Thanks in advance for any input!

regarding the ac.

take your total watts, multiply by 3.41 to get btuh produced.

not including the wattage of your fans, i came out to like 15kbtuh.

then add your total external heat gain. in your case, its a room within a room... so the heat gain is going to be negative seeing as how this room will be warmer than the room it resides in. this means you will loose at most a couple hundred btuh if you insulate it modestly...cheap r13 batts.

if its uninsulated with only 1 layer of drywall you might loose as much as 1kbtuh, but probably much less.

so like... 15kbtuh + 2000 btuh (to cover additional fans and dehuy equipment etc.) + latent heat gain X 120%( to cover bad calculations, bad install, bad equipment etc.).

its important to properly size the ac system, as this is you main dehumidifier right here... a properly sized ac system will be removing the vast majority of your humidity.

when you oversize an ac, it cycles too frequently, removing less water.

what you want is your ac system duty cycle to approach 100% at your peak heat gains. it might be prudent however... to size the system with the expectation that it could function in the event that the houses main AC system is broken, but that's up to you.

regarding the 'best' manufacturer... i don think anyone will contest its the Mitsubishi? they at least the most popular... but not my personal choice being they cost too much imo.

regarding the dehumidifier.

its very hard to calculate the humidity gain(latent heat gain) from a system like this... being that you have the plants transpiring a great deal of moisture in ever increasing volumes as they grow.
some plants are kept small, while others allowed to grow rather large.

the best information ive ever seen is, something like 50% of PAR wavelength energy is converted to latent heat gain in greenhouses. however this is an empirical observation, and not a guideline.

if i were in your shoes id measure the amount of water missing from the grow system during lights on and lights off.

it takes something like 1000btuh to condense a lb of water(check that figure), so i would find the lbs of water missing divide that by hours lights, and find a btuh latent heat gain figure.

then you would size the dehumidifier to that capacity, then take the heat gain from the dehumidifier based on inefficiency, (power required to condense an lb of water) and add this back to the total heat gain.

that's how i would do it. ironically though, it probably wont matter as you wont find a dehuy at exactly what size you need, so will likely end up over sizing anyway. but its an edifying experience to do the math regardless of the overall outcome.

regarding a humidifier.

i cant see any reason why you would want one. even when your plants are too tiny to produce any appreciable amount of water vapor, your lighting load will also be very small.


regarding fan and airbox.

no clue what that is. presumably its some sort of inline fan with a carbon filter.

no comment on this. no experiance.


positive pressure.

why would you want positive pressure in this room? if anything i would think you would want negative pressure.

i would not introduce positive or negative pressure to any part of my house personally. its going to interfere with your central heating and ac delivery. assuming its forced air and not radiant or hydronic.

its also going to push conditioned air or pull unconditioned air into or out of your house raising your heating or cooling costs.

 

[timmur]

The positive pressure is to keep micro organisms out of the grow space. Doesn't have to be much. Defiantly don't want negative as this allows "stuff" to be pulled into the room.

The fan and carbon filter are meant to recirculate the air to remove odor.

Sounds like you're saying that humidifier isn't necessary as there will always be a need to remove moisture from the air. If so, would this be true during both lights on and off? It's easy enough to ditch the humidifier if it's not needed, but the original thought was to control humidity under all circumstances.

 

[Granger2]

I've never needed a humidifier. I'd buy one later if needed. Good luck. -granger

 

[queequeg152]

Sounds like you're saying that humidifier isn't necessary as there will always be a need to remove moisture from the air. If so, would this be true during both lights on and off? It's easy enough to ditch the humidifier if it's not needed, but the original thought was to control humidity under all circumstances.

more or less yea... unless you live in the bone dry desert, or frozen tundra. even then though, you could probably do without a humidifier. even then its hard to imagine needing one seeing as to how this rooms is going to be close to sealed.

worst case during lights on with few plants, your ac will be running and humidity will be lower-yes this is a given, but you still have the option of increasing the air handlers speed, thereby removing less humidity. if the humidity is still too low then you can just unplug your chiller and let your water temps increase.

supplementing with sodium hypochlorite will kill pretty much all organisms in the fertilizer solution.

if its still an issue... then reevaluate your building and look for air leaks etc.

the biggest reason why alot of homes need humidifiers installed is because they leak to much air. daily activities such as showering and cooking and breathing should keep the humidity levels reasonable.

pumping your house full of humidity when its cold outside is a HUGE potential mold hazard. any hot moist air leaking out of the conditioned space could easily condense inside cold exterior walls and become a costly problem.

in some rare cases, people need like 60%+ humidity for health reasons, but most don't, and lowish humidity just isnt a problem.

 

[timmur]

Our house is usually at 20% to 25% RH year around. We're in high desert. My wife is complaining that we need a whole house humidifier.

 

[queequeg152]

Our house is usually at 20% to 25% RH year around. We're in high desert. My wife is complaining that we need a whole house humidifier.

20-25% is on the low edge of what is generally considered acceptable. below 20, and health professionals claims you might suffer problems with your lungs, but i don't know the details of this.

supposedly people with lung related issues are more sensitive to low humidity, but i don't know the details about this either.

id suggest investigating your house for air leakage rather than buy a humidifier for the reasons i mentioned above. ill link some junk to read at the end of this post.

a few points against adding humidity to your home

generally speaking, as humidity goes up, so do problems with mold growth on surfaces.

the colder your outside air temps get, the lower your indoor RH needs to be to prevent condensation on older windows. if you have older single or double pane windows with metallic spacers you could very easily see condensation on your windows perimeter when outside temps drop.

if you have any wood flooring or wood furniture, or old wood doors etc, you could potentially have issues as the wood has, over the years become conditioned to your low humidity.
with that said, from what i understand... this is not usually a real problem, and more often than not, the issue of wood shrinkage or warpage is overblown.

regarding your grow space. provided you are not leaking excess amounts of that 20%rh air into your grow space, you should not have much of an issue. however... considering the POTENTIAL for humidity issues here, id recommend you be extra fastidious in your air sealing... get a dow froth pak single part air sealing kit, or a foam gun and some dow enerfoam cans. i recommend the latter.
paint your drywall with a low perm paint... its not a huge path for moisture, but it IS a path... especially at high vapor pressure differentials.

links:

http://buildingscience.com/documents/insights/bsi-035-we-need-to-do-it-different-this-time

http://buildingscience.com/documents/reports/rr-0203-relative-humidity/view

http://www.energyvanguard.com/blog-...fier-Is-a-Bandaid-The-Problem-Is-Infiltration

i just googled, "building science humidifier". theres other junk to read if you are interested.

 

[timmur]

Thanks queequeg152. I'll take a look at the provided links. My primary concern is if I'll need to humidify at all in the grow space.

BTW, the building is a modular walk-in cooler design.

 

[queequeg152]

holy hell. a walk in cooler? do you know how much those cost?

not to be a ****, but that is beyond overkill. you are building this room INSIDE your already conditioned space right?

those walk in fridges are basically sheets of metal clad SIP panels with at least 4" of hard core insulation... r20+.

you need that much insulation when you are trying to maintain a freezing atmosphere without spending shitloads on ac.... like a resturant trying to keep 100's of lbs of meat frozen. the temp delta across a freezer wall is going to be around 50 degrees F.

the temp delta across your grow room will be like 10 degrees F, AND the heat flux is negative, meaning its trying to LEAVE this room. super insulating like you propose will actually very slightly increase the amount of energy you need to cool it.

save your money bro... while you are at it, build your own undercurrent. 1600 bucks? fucking absurd.

 

[timmur]

Yep I'm aware of all that. Not gonna build an Under Current and not gonna use a tent or build out the whole room. Yes expensive, but that's how it is. I have zero handyman skills, no tools, and no desire to do any of it. I got a deal on the cooler so it only cost slightly more than a 10 x 10 Secret Jardin Intense, but still painfully expensive.

 

[Phaeton]

I live in the frozen tundra. The RH for much of the year is less than 10 and for a few months the average less than 5.
The inside RH averages 10 to 20 all winter. This bothers my lungs more than it bothers the plants.
My four plant perpetual transfers six gallons of water into the atmosphere during 12 hours under 3500 watts (2000 on top 1500 on sides) of lighting. Transferring only 1-1/2 gallons during the 12 hour darkness to give my room a 4:1 light to dark water usage.
The likely cause of this high water use is ambient RH of under 20 (the meter is reading 16 RH right now above the plant canopy). Not sure how to extrapolate the numbers but I would guess doubling the RH to 40 would cut the water use by a third.

I am half and half CMH/LED because LED causes less heat at the leaf surface and less water escapes.
Works for me but in a humid area having a higher leaf temp would help the plant breathe.

The only fixed rules are the ones discovered in one particular garden, move a mile and the rules change.

A note on Far Red. I have only two harvests with one strain so far but while using the extra hours of light makes the buds visually and physically larger the weeks taken to mature has not changed. The strain is a mostly indica hybrid without a commercial name.

The further north the plant's genetics come from the more effect the Far Red should have, currently I am finishing a new room for autoflowers with 18 hours full spectrum and 6 hours Far Red. The sky never does quit glowing this far north where the autoflowers came from.

 

[Avinash.miles]

DAMN timmur, sounds like an awesome setup, i really hope you plan on documenting it in a grow journal here on icmag.... i love the big undercurrent system grows, and i'm a big fan of CMH lites...

 

[timmur]

I live in the frozen tundra. The RH for much of the year is less than 10 and for a few months the average less than 5.
The inside RH averages 10 to 20 all winter. This bothers my lungs more than it bothers the plants.
My four plant perpetual transfers six gallons of water into the atmosphere during 12 hours under 3500 watts (2000 on top 1500 on sides) of lighting. Transferring only 1-1/2 gallons during the 12 hour darkness to give my room a 4:1 light to dark water usage.
The likely cause of this high water use is ambient RH of under 20 (the meter is reading 16 RH right now above the plant canopy). Not sure how to extrapolate the numbers but I would guess doubling the RH to 40 would cut the water use by a third.

I am half and half CMH/LED because LED causes less heat at the leaf surface and less water escapes.
Works for me but in a humid area having a higher leaf temp would help the plant breathe.

The only fixed rules are the ones discovered in one particular garden, move a mile and the rules change.

A note on Far Red. I have only two harvests with one strain so far but while using the extra hours of light makes the buds visually and physically larger the weeks taken to mature has not changed. The strain is a mostly indica hybrid without a commercial name.

The further north the plant's genetics come from the more effect the Far Red should have, currently I am finishing a new room for autoflowers with 18 hours full spectrum and 6 hours Far Red. The sky never does quit glowing this far north where the autoflowers came from.

@ Phaeton, thanks for the RH/water use info and the far red insight!
@ Avinash, yes I do plan to document my efforts on Icmag. I'm sure I'll need some advice!

 

[Intimea]

I'm in for the show.

 

[queequeg152]

I live in the frozen tundra. The RH for much of the year is less than 10 and for a few months the average less than 5.
The inside RH averages 10 to 20 all winter. This bothers my lungs more than it bothers the plants.
My four plant perpetual transfers six gallons of water into the atmosphere during 12 hours under 3500 watts (2000 on top 1500 on sides) of lighting. Transferring only 1-1/2 gallons during the 12 hour darkness to give my room a 4:1 light to dark water usage.
The likely cause of this high water use is ambient RH of under 20 (the meter is reading 16 RH right now above the plant canopy). Not sure how to extrapolate the numbers but I would guess doubling the RH to 40 would cut the water use by a third.

I am half and half CMH/LED because LED causes less heat at the leaf surface and less water escapes.
Works for me but in a humid area having a higher leaf temp would help the plant breathe.

The only fixed rules are the ones discovered in one particular garden, move a mile and the rules change.

how well sealed is your grow area?

 

[McKush]

Good luck with your build timmur.

 

[timmur]

Thanks McKush. Waiting for a visit from the contractor for the electrical. I hope to get started within the next couple of weeks.

 

[timmur]

So I settled on a layout and the equipment. The pic below is my feeble attempt to layout the space using Excel. It is drawn to scale. The room is 10'8" by 15' and the actual grow room is 8' x 8'.

I asked Cycloptics for a model of the room and the results are attached. Since I spoke with them I changed the size of the room by moving the Under Current epicenter outside the room which let me drop down to 12 Greenbeams from 16.

The door to the room is in the upper right.

 

[digging]

Check out the suggested RH levels RDWC require in both vegging stage and flowering stage, any you will probably discover your going to need a humidifier.

In the vegging stage the RH needs to be quite high.

 

[Granger2]

http://www.botanicare.com/Grow-Room-Layouts.aspx

Ideas here. -granger