Advice on exhausting out window

[Moe.Red]

OK, set let's get back to basics. Starting with this picture:

And we can do some figuring as to what is needed. Lets go thru this example, and then we can change the drawing to fit your specific needs.

In the standard vented growspace / lung room arrangement, the goal is to condition the lung room to be the desired parameters for optimum growth. A common alternative is what is the best I can accomplish given my space / budget / wife looking over your shoulder / put your issue here. Let's solve for the optimum to start with, so at least we have a target.

Gotta start somewhere, so let's pick a 4 x 4 growspace with a Spider Farmer SE 7000 light. I picked that because @Aqua Man is doing exactly that setup in his garage with a window AC unit, and we can ask him to take some readings if needed.

Assuming the lung room is sealed off from your HVAC system (garage, shed), you can do whatever you want and not impact any other living space. If this lung room is a room in your house, you have to take that into consideration. Will I be using my house AC to help condition the lung room? What if I am too hot and the furnace is running? You might decide to close off this room to make the lung room it's own system, which is where the portable AC or window units come in.

Then there is the humidity. Depending on your grow style you may be putting 10 gallons of water a day into the air. At the height of Veg in a 4x8 I get there some times. This is a problem, more so than humidification. A 50 lpd unit from Home Depot will not handle that load.

So what is ideal? There are tons of caveats. Hydro? Soil? CO2? Lighting? Skill? Genetics? Obviously anything I say here is a generalization.

78*F Daytime. 70* or lower over night.

This would give you a leaf temp of about 74* under LED, which when you run the VPD, you want RH of 51.5% for a VPD of 1.0. VPD needs change as the plants grow in stages. You will either need to control your temp or RH throughout the grow, correcting as needed to maintain proper VPD.

Whaaaa, what's this VPD crap? Again, I am talking about ideal. The VPD you give the plants set the pace of respiration. Think of it as the amount of energy in the atmosphere which sucks the water thru the plant like a straw, or shuts it off. The amount of water, therefore nutrients is what you are controlling with temp and RH.

With the stomata closed, it doesn't matter how nice your nute regimen is, they ain't getting to where they need to be.


OK so what if I can't maintain 78 and it gets to 90F and stays there? It happens all the time. You either adapt and prepare for a weaker harvest, or you don't adapt and the plants go to shit or die.

RH is important for other reasons too - like mold. Bud rot sucks ass. PM can bite my dick. Keeping it under 60% in flower should be a hard limit not to exceed, and lower is better. within the correct VPD range.

So, in the simple lung room example above, if you want to grow proper indoor weed, you need to have both AC and a proper dehumidifier. Size will need to be calculated based on your situation.

If you want to talk specifics, let's adjust the drawing to match your situation and go from there. Need climate info too.

 

[Aqua Man]

Yeah you need to calculate 1-1.5gal per day per plant on a deguey to ensure it will be adequate.

@Moe.Red nailed everything there so be sure to really understand all that

 

[IamN2pot]

With the stomata closed, it doesn't matter how nice your nute regimen is, they ain't getting to where they need to be.

No truer words were ever spoken!!!!!

 

[Moe.Red]

So do you recommend both a dehumidifier and portable AC or are you referring to the dehumidification the portable AC will be doing naturally? I won't be able to mount the AC in a window it will have to literally be a portable one, but I can exhaust it out the window still correct?

I didn't quote your post but my last reply was to this. We can check your math to make sure it will work. But you will potentially need a secondary dehumidifier, depending on what and how you are trying to grow. How many plants?

 

[bananabud]

So basics are, tent is 5x5x6.6 lights are 2 600w LED two 440 cfm inline fans with a hepa filter for the intake (kinda cone shaped like a cold air intake) and a charcoal filter exhaust. Prior set up had exhaust fan inside the tent but the charcoal filter outside top with no smell issues and the intake fan and hepa filter out side bottom.

In a standard bedroom with an attached bathroom so AC vent in both bed and bath. Not a lot of room but some left over would be enough for portable ac and or dehumidifier, also includes a calif. king bed, tall dresser and night stand. There are two standard size windows but one is not accessible due to tent.

Planting plan is only 4 plants, 6 made it too crowded and I felt the need to add extra lights as they got bigger which increased the heat and while all was okay I ended up needing to leave the tent open more and I didn't want that. Our watering schedule was about a gallon per plant every other day, based on moisture levels in the soil. Will upload a few pic next where you can kind of see in the tent.

 

[bananabud]

Tried to get some that actually showed the set up, but turns out of so many pictures of the grow not many showed anything but plants

 

[bananabud]

I didn't quote your post but my last reply was to this. We can check your math to make sure it will work. But you will potentially need a secondary dehumidifier, depending on what and how you are trying to grow. How many plants?

See below, I don't know the actual measurements of the room, but I'll dig out a tape measure today and see.

 

[growsince79]

HVAC guys cringe when they hear about people actively pushing air outside of an otherwise central air conditioned space. It really plays havoc with the AC design. You will have a negative pressure on the whole house and will be sucking in make up air on every window, every crevice in the house. You will then force the central air to cool that make up air - which can be significant with a 6" blower working against it.

Better to make the lung room it's own unit and use AC and Dehumidifier to get the lung room air where you want it and exchange air that way. It might seem counter intuitive, but the the electricity use will be less in this scenario.

Good point, I never even thought about that. I guess I've been doing it wrong all these years. I blow the exhaust outside and don't need a dehumidifier and AC for a lung room. Although I haven't done any comparisons, I'm sure the little extra power used by the central ac is nothing compared to the cost of running a dehumidifier and portable AC.

 

[Moshmen]

HVAC guys cringe when they hear about people actively pushing air outside of an otherwise central air conditioned space. It really plays havoc with the AC design. You will have a negative pressure on the whole house and will be sucking in make up air on every window, every crevice in the house. You will then force the central air to cool that make up air - which can be significant with a 6" blower working against it.

Better to make the lung room it's own unit and use AC and Dehumidifier to get the lung room air where you want it and exchange air that way. It might seem counter intuitive, but the the electricity use will be less in this scenario.

I do exactly this ^ except I do exhaust a flower tent outside because my dehuey can’t keep up - it does cause other minor issues for me next year I’ll have a bigger dehumidifier- before I exhausted outside I was removing 3-5 gallons every day! And my tent still ran humid at lights out especially so this was my short term fix , I will exhaust in the room this winter and from now on .

 

[Moe.Red]

See below, I don't know the actual measurements of the room, but I'll dig out a tape measure today and see.

Based on the visual not math I would say you could use your portable AC exhausting to the outside in that bedroom and see what it gets you. The most simple solution would be to leave it as part of the house and set the portable AC in that room to the same temp as your house. Then if you need to, stick a dehumidifier anywhere in the house like a basement. Your whole house will be your lung room.

If that does not perform to your standards, next step is to close off the bedroom from the main house and put the dehumidifier in the bedroom along with the AC. You have a healthy amount of plants there and you will need a fair amount of dehuey in conjunction with the AC to get it in the right VPD range. But you can run it high RH if you want, just less vigorous and watch for mold.

Amazon.com

That will allow you to dial in your VPD. If that is not important to you, go cheaper.

Both the dehuey and AC need a direct drain. Don't mess around with buckets or anything like that. Since you have a bathroom close you could do this:

Amazon.com

That's my best advise to get you started where you know what you are getting into and not buying anything you don't need if this is more than a casual hobby. The best indoor weed is the stuff you ran straight down the fairway the entire grow and did a perfect harvest. Then lighting is what I would look at next. And switching to hydro lol. I'll spend all your money

 

[Moshmen]

Good point, I never even thought about that. I guess I've been doing it wrong all these years. I blow the exhaust outside and don't need a dehumidifier and AC for a lung room. Although I haven't done any comparisons, I'm sure the little extra power used by the central ac is nothing compared to the cost of running a dehumidifier and portable AC.

Where I’m at the difference is almost $3.75 a day! - I track my daily usage

 

[growsince79]

Where I’m at the difference is almost $3.75 a day! - I track my daily usage

My 2 x 4 setup runs about $1 a day for everything.

 

[Moe.Red]

Where I’m at the difference is almost $3.75 a day! - I track my daily usage

Why do I love data so much?

$1350 a year difference in Fuggin Fry yo balls hot Florida.

I've never exhausted outside, I dunno what my difference would be.

My tents are actually sealed and CO2 injected, so the mini split was needed. And I have been thru so many dehumidifiers I'm embarrassed. I need that big boy when I push. All the little Home Depot ones are crap that lie and die. But let me tell you what I really think lol.

With the CO2 injection, pinpoint VPD, fully spectrum adjustable lighting, and some other goodies from Aqua, this is going to be the most pinpoint grow I have ever done.

I already told you but for everyone else, Moshmen sent me some IBL Durban Poison. Regs. Photos. Like the real stuff I hope! I'll pick the best female out of this lot and clone her 8 times and she gets the maiden voyage in this new tent / software setup I'm doing. My first foray into O2 injected fogponics.

Sorry for the side track, I'm just excited like a virgin on prom nite.

 

[growsince79]

Why do I love data so much?

$1350 a year difference in Fuggin Fry yo balls hot Florida.

I've never exhausted outside, I dunno what my difference would be.

View attachment 1280356View attachment 1280357


My tents are actually sealed and CO2 injected, so the mini split was needed. And I have been thru so many dehumidifiers I'm embarrassed. I need that big boy when I push. All the little Home Depot ones are crap that lie and die. But let me tell you what I really think lol.

Here in OK it's finally under 100f daytime. If I had to spend that much extra, I'd just grow outside. My volunteer survived 115F and is making sticky stinky buds.

 

[Moe.Red]

My 2 x 4 setup runs about $1 a day for everything.

Your growing style is the complete opposite of mine, but everything you grow looks so healthy. Proof that low budget simple setup can work in experienced hands.

 

[Moe.Red]

Here in OK it's finally under 100f daytime. If I had to spend that much extra, I'd just grow outside. My volunteer survived 115F and is making sticky stinky buds.

lots of water. They can make it. Their ancestors sure did without our help. Just not ideal.

 

[Moshmen]

My 2 x 4 setup runs about $1 a day for everything.

About the same then I got 4x4and2-2x4’swith at least one in veg all the time

 

[bananabud]

Based on the visual not math I would say you could use your portable AC exhausting to the outside in that bedroom and see what it gets you. The most simple solution would be to leave it as part of the house and set the portable AC in that room to the same temp as your house. Then if you need to, stick a dehumidifier anywhere in the house like a basement. Your whole house will be your lung room.

If that does not perform to your standards, next step is to close off the bedroom from the main house and put the dehumidifier in the bedroom along with the AC. You have a healthy amount of plants there and you will need a fair amount of dehuey in conjunction with the AC to get it in the right VPD range. But you can run it high RH if you want, just less vigorous and watch for mold.

Amazon.com

That will allow you to dial in your VPD. If that is not important to you, go cheaper.

Both the dehuey and AC need a direct drain. Don't mess around with buckets or anything like that. Since you have a bathroom close you could do this:

Amazon.com

That's my best advise to get you started where you know what you are getting into and not buying anything you don't need if this is more than a casual hobby. The best indoor weed is the stuff you ran straight down the fairway the entire grow and did a perfect harvest. Then lighting is what I would look at next. And switching to hydro lol. I'll spend all your money

Thanks so much for the advice and links. This is what I'm going to do and I'm not going to wait to get the humidifier, according to my thermostat the humidity in my place runs between upward of 40% most of the time, seems odd for the desert but I'm about 100 miles NE of Phoenix around 5000 ft. We used a humidifier in the tent but just in the very early stages until they started taking in more water and respirating more, after that stage it wasn't necessary. I've looked into hydro when I decide to try it, I'll do a separate trial tent lol. Yes upgrading my lights is next on my list especially if I can get AC and Dehumidifier dialed in.

 

[pilto]

Moshmen sent me some IBL Durban Poison. Regs. Photos. Like the real stuff I hope! I'll pick the best female out of this lot and clone her 8 times and she gets the maiden voyage in this new tent

Ummm...do tell...? Love to get my hands on some real Durban Poison.

 

[Mikedin]

This is my second grow in a 5x5x6.6 tent. I have two inline 440cfm fans a hepa intake filter and a charcoal filter. Last grow my intake and exhaust both came directly from and to the indoor room I share with the tent, with both filters being outside the tent. I purchased a window AC vent kit and want to put the charcoal filter inside the tent and exhaust out the window everything I have is 6". Do I need a backdraft damper? How do I make sure nothing, like bugs get in? Is there anything else to be worried about?Any other suggestions would be greatly appreciated.

I used just a regular drier vent cover, same color as the rest on my home so it would blend in, one in the front of the home hidden out of view under a low deck, and 2 in the back I only have them for emergencies for extreme heat now cus I can keep a constant 80-83f in my tent even exhausting into my lung room, basement stays cool