Reconfiguring my indoor exhaust setup

Growroom Design
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So, I’ve been growing indoor year-round for a few years now, but two factors changed this year that makes it very difficult to maintain a good temperature and humidity in my tents.

  1. It is much warmer this year. Outdoors, this week alone was 104F pretty much every day, with humidity in the 90-100% range. It is usually very humid here, but we also usually get enough rain to drop the pressure. Not much at all this year, and long heat and humidity streaks as a result.

  2. I added a new lung room with a new tent – more about my setup follows.

So, both of my lung rooms (the room where tents reside) are sealed in a furnished basement. 1 of my lung rooms contains 2 tents – a 3x3x6ft with a 300W LED, and a 2x4x5ft with a 240W LED. The new lung room has a 3x3x6ft with a 260W LED. Each tent has an active outtake inline fan, controlled with thermo-hygrometers and software I wrote to switch on a mini heater in the tent, or the exhaust fan.

Inside both lung rooms is a good AC unit (which can function as a dehumidifier if needed, but I’ve found the drying of the air by AC-mode alone is sufficient). These AC’s vent through separate 6in ducting through the wall to an adjacent, unfurnished side of my basement. This side has 3 windows that I leave open for warm air to escape, but I don’t run the ducting to the windows – they stop near the wall they go through.

Now, this unfurnished side of my basement that is collecting all the heat has always been warm from this setup, and my VPD has always been spot on, until this past week when it became much hotter, when I added the new lung room, from more hot AC air exhausting, and hotter weather to boot. It turns out, the reason why is because I also vent the active tent exhaust systems into this same room, and backflow of heat occurs when fans are not running or are low enough speed.

As a quick fix, I bought duct-work and vented both AC’s in the exhaust room to windows, which helped a tiny bit, but not much, and I’m still not able to get the consistency I have had before this new lung room and heat wave.

My new plan, and this is where I would like some opinions, is to vent the tent exhausts into the same room as the tent, and rely on the desiccation of the heavy-duty AC’s to dry the air and recycle new air for the passive intakes. After all, the problem is primarily that the AC exhaust is very hot and backflowing through the fan exhaust duct-work from the room I exhaust into.

I do not have enough window space to exhaust all 3 tent fans to a window, nor do I have room to run all that duct-work, but given where the AC’s exhaust through the wall, I have managed to vent the ACs to a window as previously mentioned.

Do you think this is a solid plan? Right now I’m barely managing to keep my VPD levels sane, and I’m running hotter than I’d like in mid-flower, so I need a low budget (disabled, close to zero income) solution, which is the primary reason I wanted to try this, as it sounds logical to me.

Thanks in advance!

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Have a look at an insulated duct in the run to the window. I was getting too much heat buildup from the single pane windows and insulated them as well, that helped.

Cheers
G

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My english is average, but with a quick draw (no one expect michelangelo be sure) it will be easier to figure out the equation.

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It’s unfortunately not really an option due to space. Ceiling is low in basement and got other runs and appliances in the way.

To make matters worse, my window isn’t sealing the exhaust because they are those small basement hinged windows that only open slightly (pull out at an angle).

I have a 6in AC line going into the wall, that is clamped to and then foil taped with a 25ft AC Infinity 6in line.

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I’m mainly curious about my plan to remove the tent exhaust runs, and just exhaust into the tent rooms themselves. It should help with the heat from the AC exhaust backflowing into the tent room, which would make the AC and tent fans more efficient I would think. I haven’t done that yet though, because I’m still thinking about things. I’m also on a next to zero budget after just splurging on a new tent, light, and equipment for those runs, with pretty much no income at the moment. So I don’t want to have to buy anything extra, because it would take a while to do so.

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Well my wife went out and got me 2x 25ft runs of 6in insulated ducting, which was like $110usd. And some foam board to try to seal the windows where they will vent. I hope I can fit this duct around everything and I hope I can make a good seal with the foam board. New project. No experience. What could go wrong? :laughing:

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Ouch, the price has gone up on that stuff… :roll_eyes:

That’s a good missus you got there. :+1:

The foam board should work, you need some oversize washers if you use fasteners like nails or screws (easy to make your own). if you have to set it back from the glass you can usually frame around the existing window.

I mounted an exhaust cap and then attached the duct to that but you could just run the duct through the foam and a worm gear clamp on the other side to hold it in place.
Think about covering the end of the duct with window screen if venting directly outdoors.

hope this helps

Cheers
G

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I was thinking of just sealing it with foil tape so I can remove it. The windows are weird. The glass pulls at an angle until perpendicular. Here is a quick shot:

image
image2674×1504 265 KB

I’m just not sure how to mount the flimsy duct to the flimsy foam yet.

I measured about 1 1/2 inches between the screen and the edge of the glass pane when it is fully open. My foam board is half that at 3/4in. I got enough to cut out 3, maybe 4 sections of the 11.5x30in sections I need.

But I have 2 windows, one closer to another AC unit’s exhaust line, so I want to duplicate the work.

Also, it’s not my house but my parents so I can’t really make any damage, as these windows were just put in last year (~50 year old house).

My thinking cap is still on. I don’t want to mess this up. Any feedback is welcome. I might do some work tomorrow if I’m feeling confident.

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I don’t have the plastic coupler like you see in the image for the other AC. I looked high and low today and it must’ve got tossed. Was thinking of putting that through this window’s foam board, but not sure how to attach the other one yet. Or if that is even a good idea. I’m pretty lost in my head right now lol

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Just a suggestion:

Do you have duct work that feed registers to the rest of the house? If you do, I’m assuming you have the AC running in the house since it’s so hot outside. Find a spot to tap into your main air handling system and just intake to the tent and vent to the house. You won’t need an AC unit for your tent or lung room, so you won’t have to worry about adding heat to the house and you have a closed loop system tied into your home.

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I wasn’t allowed to do that. It would involve damaging the sheet metal duct box.

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The ducts are square and not tube in the basement?

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Correct. And I don’t have the tools or directional flow knowledge to even do that, if I was allowed to.

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That movable horizontal window, does that look removable? That would simplify issues.

The frames, are they vinyl coated wood? Would you count 4 holes into that as damage? (I’m thinking #6 screws)
Whatever mods happen, that molding strip will have to be removed (store it and put it back later).

Assuming no to the above questions and ‘work with what you see’…
cut a piece of foam and block the bottom half.
Now you need to secure the end of the 6" duct to blow out through the screen… depends how handy you are… I’d think of making a fixture to hold the scrunched hose (looks like a 4.5" opening?)
A base that would sit on the glass but with minimum play. That joist above could be the upper anchor point. Finish by blocking in with foam.

There’s more than one way to skin a cat…

Cheers
G

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The window may be removable. I’m not sure how that would play out, with being allowed to do that though.

The frames are vinyl, period.

What looks like a 4.5" opening?

Thanks for the help so far.

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You can cut down on the heat tremendously by going to a full room dehumidifier and get rid of the AC units. They’re not as efficient as a dehu.

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To be quite honest, I have a large AC/dehu combo in both lung rooms, and it stays dry and cool with them on AC mode, and I still empty about 15gal per day out of each basin, same as with dehu.

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The problem with dehu mode is it is computerized and crap, and my humidity graphs look like crap. I can see the condenser kicking off every 15 minutes or so, when the room is nearly saturated (very high humidity here). AC mode works continuously, and accomplishes the same as when the condenser is on.

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Also, dehu mode raises temperature too much, now that I remember. The tents emit quite a bit of heat into the surrounding lung room without it on AC mode.

My AC gives me not drips, but a steady stream of water draining. It’s pretty crazy to be honest :laughing:

My lung room is very happy humidity wise, and thus, my tents. The temperature only became an issue when I added the second lung room, that vents into the same area both AC’s and all the tents exhaust into (backflow I’m assuming).

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What are the temps and what are you growing?

I realize there are “optimal” conditions that we all strive for, but this plant grows in some of the hottest and humid environments on the planet (outdoors) and does just fine.

Obviously, it’s cultivar dependent.

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