Cooling and negative pressure advise needed

[HansBud]

how's it going RIU with spring time around the corner I just wanna make sure my new room will continue to be cooled and smell proof

First off I built a room out of plywood and insulated it with pink insulation batts. The room I built is inside of a non insulated concrete barn/garage. Inside the room I built I set up my grow tent because I could not obtain negative pressure in the room alone and needed to contain the smell so my tent worked perfect in regards to negative pressure working with my carbon scrubbers

Now for the details

The room I built is 10 feet long by 7 feet wide and 8 feet tall everything is insulated the floors wall and ceiling the tent I have inside that room is 5x5x7
The temperatures
This is where it gets weird as I kind of have to go along with mother nature
Inside the room I built the temps stays at 55f on by the floor and about 62f by the ceiling which is perfect as the tent stays at 80f at the top of the canopy and 73-75f by the floor.
For my exhaust I have two 200cfm inline fans at the top of the tent each on opposite sides and each with a 200cfm phresh carbon filterand they exhaust into the room I built and also a medium sized fan just to push air around
For the vents I have two holes open about half way up the tent on one wall (shown in picture) that pull in a good amount of air to cool the tent
The lights I have are 4 Mars hydro 300s on 24/7 as I run autos

Now my concerns are with spring right around the corner the temps will be rising right now it's around 20'sf but in summer it'll be 80-90f.

This where my main questions are

OK so right now everything works fine which means having the room.i built at 55f, this is a problem because there is no way I can keep it that cool during the summer I have a 5000 BTU AC unit I plan on putting in the room I built ( I have a piece cut out of the wall for the AC unit to mount into) but I know the AC alone won't cut it I can probably get it to 65 at the lowest.

So I believe I have 2 options

Option 1- instead of exhausting into the room I built I could exhaust into the barn that way the heat from the lights wont be heating up the room I built. My only concern with this way is that it still might not be enough to cool the tent and won't know until it's done

Option 2- just say screw it and take the tent out if the room I built and purchase an 800cfm fan and a carbon filter to go with it and cut a hole in the room I built and exhaust that into the barn. With this option I don't know if that will be enough cfms to create negative pressure for the room and if it is if it will just suck all the cold air from the AC out and not cool it effectively


Sorry for such a long post I just wanted to try and detail it as much as possible I also apologize for the absence of pictures as I am at work and will get some uploaded in a couple of hours

I am open to any answers and gladly appreciate your input!!

 

[Feracon]

What's the R value of your insulation? Are you using R15 4" thick insulation? Make sure your installation is as air tight as possible and your flanges are taped.

You don't need an 800 cfm exhaust fan, thats just going to pull hot air into your interior room really fast.

The interior building/room

I'd get a wall mounted air conditioner, cut your interior building's wall and mount the AC there, make sure it's a tight install. You're working with 560 cubic feet, so you'll need an AC unit that pushes at least that.

Then I'd cut a port on the opposite wall of your interior room and install an in-line duct fan with equal CFM rating as your AC, maybe a little higher. Hook your AC up to a thermostat controller like this:

https://www.amazon.com/bayite-Pre-Wired-Temperature-Controller-Thermostat/dp/B01KEYDNKK

Set it up so that when the temp reaches a low threshold the AC turns off and now acts as a passive intake.

The tent

Open the passive intakes around the bottom of the base of the tent and use an exhaust fan inside your tent rated at least 175 cfm.

Don't forget to mount your controller's probe inside the tent not inside the room it's in.

General

I'd recommend also setting up a relative humidity controller with a dehumidifier, again mounting the probe inside the tent.

Mount all of your controllers outside the room that contains the tent so that you can monitor without opening it, avoid light pollution, and keep it out of potentially high humidity.

 

[HansBud]

What's the R value of your insulation? Are you using R15 4" thick insulation? Make sure your installation is as air tight as possible and your flanges are taped.

You don't need an 800 cfm exhaust fan, thats just going to pull hot air into your interior room really fast.

The interior building/room

I'd get a wall mounted air conditioner, cut your interior building's wall and mount the AC there, make sure it's a tight install. You're working with 560 cubic feet, so you'll need an AC unit that pushes at least that.

Then I'd cut a port on the opposite wall of your interior room and install an in-line duct fan with equal CFM rating as your AC, maybe a little higher. Hook your AC up to a thermostat controller like this:

https://www.amazon.com/bayite-Pre-Wired-Temperature-Controller-Thermostat/dp/B01KEYDNKK

Set it up so that when the temp reaches a low threshold the AC turns off and now acts as a passive intake.

The tent

Open the passive intakes around the bottom of the base of the tent and use an exhaust fan inside your tent rated at least 175 cfm.

Don't forget to mount your controller's probe inside the tent not inside the room it's in.

General

I'd recommend also setting up a relative humidity controller with a dehumidifier, again mounting the probe inside the tent.

Mount all of your controllers outside the room that contains the tent so that you can monitor without opening it, avoid light pollution, and keep it out of potentially high humidity.

Awesome thank you for the reply I figured I'd have to get some temp controllers and such

Im a little confused as to what you mean about the port on the opposite wall of the AC would you put the inline fan blowing out of the room.into the barn? Or vice versa? This seems like it should work so.ill give it a try

 

[HansBud]

And here's some pics I got last night not the best but maybe theyll work


Here's the room itself


Here's the tent when walk in (it's tight in there)


This is opposite side of the tent


Here's a front view of the open tent


This is where my cool air is forced into the tent I would do bottom.flaps but the baby's on the floor don't like it that cold down there

 

[nfhiggs]

What's the R value of your insulation? Are you using R15 4" thick insulation? Make sure your installation is as air tight as possible and your flanges are taped.

You don't need an 800 cfm exhaust fan, thats just going to pull hot air into your interior room really fast.

The interior building/room

I'd get a wall mounted air conditioner, cut your interior building's wall and mount the AC there, make sure it's a tight install. You're working with 560 cubic feet, so you'll need an AC unit that pushes at least that.

Then I'd cut a port on the opposite wall of your interior room and install an in-line duct fan with equal CFM rating as your AC, maybe a little higher. Hook your AC up to a thermostat controller like this:

https://www.amazon.com/bayite-Pre-Wired-Temperature-Controller-Thermostat/dp/B01KEYDNKK

Set it up so that when the temp reaches a low threshold the AC turns off and now acts as a passive intake.

The tent

Open the passive intakes around the bottom of the base of the tent and use an exhaust fan inside your tent rated at least 175 cfm.

Don't forget to mount your controller's probe inside the tent not inside the room it's in.

General

I'd recommend also setting up a relative humidity controller with a dehumidifier, again mounting the probe inside the tent.

Mount all of your controllers outside the room that contains the tent so that you can monitor without opening it, avoid light pollution, and keep it out of potentially high humidity.

"AC turns off and now acts as a passive intake" Window AC units don't work that way. They pull the room air through the cooling coils, and outside air is pulled through the heat exchanger and vented back outside - they do not have free air passage inside to outside.

 

[HansBud]

"AC turns off and now acts as a passive intake" Window AC units don't work that way. They pull the room air through the cooling coils, and outside air is pulled through the heat exchanger and vented back outside - they do not have free air passage inside to outside.

Yea I think he meant it'll be like having a passive intake but it's just like having a fan that blows alot of cold air it doesn't actually take air in from the outside

 

[nfhiggs]

Yea I think he meant it'll be like having a passive intake but it's just like having a fan that blows alot of cold air it doesn't actually take air in from the outside

That's the thing - it WON'T be like passive intake. An AC unit does not have an air path to the outside.

 

[HansBud]

That's the thing - it WON'T be like passive intake. An AC unit does not have an air path to the outside.

Right it's just an AC unit , what would you do man?

 

[Feracon]

"AC turns off and now acts as a passive intake" Window AC units don't work that way. They pull the room air through the cooling coils, and outside air is pulled through the heat exchanger and vented back outside - they do not have free air passage inside to outside.

Good point. I'll think about it some more I'm sure there's a solution here.

 

[Feracon]

Instead of using a wall mounted AC unit, use a free standing unit, with an exhaust venting out of your built room. Make sure your passive intakes and AC exhaust arent near each other, preferably exhaust the AC up high, and cut your intakes down low.

Don't forget you need an AC unit with an analog switch so that when the controller flips the power on the AC turns on.