Basement ventilation advice, please!

[BarefootAndBlazed]

I set up my grow space not quite a year ago in an unfinished section of the basement. This area is long but a little narrow with concrete walls on the left and rear, while the right side is next to a bathroom so there are exposed studs (drywall on the other side for the bathroom).

I have a 5x5 in the back left corner and a 4x8 next to it along the back wall. I have one foot clearance between the tops of the tents and the joists above, with a little more room between the joists. The back right corner near the bathroom has a vent to the outside for the bathroom fan. Brilliant, right? Well, whoever installed it used a 4" tube in the basement, but it decreases to 2.5" diameter before exiting to the outdoors. I discovered that is woefully insufficient for indoor gardening. Increasing the size would involve digging near the foundation and chipping at concrete which I’m not willing to undertake.

At some point they planned for the bathroom fan to connect to a 4" diameter plastic tube that runs along the entire length of the room to the far left side.

Where does it go? Nowhere! The tube makes a 90° corner as it approaches the left wall, then stops.

The concrete wall on the left goes up 7’, but then you can see a portion of the studs and drywall above it which is the garage on the other side. My plan is to cut a hole and exhaust into the garage. My question is: how would you layout the exhaust? There are many options:
The shortest distance is to pull from the big tent to the small then out to the garage.
I could also pull out of the big tent and tie in to the existing 4" tube to go back to the garage.
Carbon filter could go in either tent.
I’m thinking an 8" AC Infinity fan would probably cover the CFM of both tents. It could go in either one, or outside. Maybe mount between the joists?
Would I be better off using two smaller fans?
I’m not sure what things will look like in the garage - just a vent? maybe a fan there too?

I’m in the beginning stages and would appreciate any input from those with experience!

[Gpaw]

An 8" AC Infinity can push 800 CFM.
Your total tent volume is 456 ft^3, or 2 ‘air changes’.

I’m not quite clear on your plan. You are going to cut a hole through the concrete left wall? or going through the rim joist above and behind the tents? Are your floor joists 10"?

On the garage side, a cheap exhaust hood (mouse proof)
Smooth wall duct has 1/10th the resistance as the flexible slinky style.

Cheers
G

[anon93244739]

Pull your air. Its easier to pull air than push it, so have a fan at the exit point, if you need more cfm add another one like halfway from tent to exhaust.

[schmarmpit]

I’d just cut a 4" hole in the rim joist and use a Y connection right at the exit so the dryer and tent go outside together. The exhaust fan should mount close to the exit, pulling air from the tents and pushing into one of the two ports on the Y connection.

[Purple-N-Hairy]

@BarefootAndBlazed, are you concerned that using a larger inline duct fan to increase the air it pulls will put too much stress on the motor? What’s the diameter of your current fan?

[BarefootAndBlazed]

Thanks for the feedback so far, folks!

The plan is to cut the rim joist (the joists measure exactly 9", which I figure is probably the 10" size, like how a 2x4 isn’t actually 2x4) and drywall just above the concrete wall on the left, near the end of the pipe with the 90° bend that goes nowhere. That will put the exhaust at floor level in the garage. Eventually I may opt to run it out of the garage altogether but for now I’ll be happy just getting it out of the garden room.

I figured it would be better to have the 8" size than something smaller (that’s what she said?) since there will be some 90° angles and a carbon filter that reduce efficiency. I’d hate to buy a fan that is just good enough at full power when for a bit more I can have a robust fan that can be dialed down.

Currently I have no exhaust at all! I gave up on using the 2.5" exhaust so I’m formulating a new plan. I circulate air inside the tents and bring fresh air in to the room with a floor fan. I had purchased an 8" Vivosun fan that only lasted a few weeks before it started making horrible grinding noises. I was reimbursed by the manufacturer and will throw those funds at an AC Infinity unit since those seem to be the best.

I will continue to use the 2.5" exhaust on the right wall for the bathroom fan. Nothing else needs to vent into the garage besides the tents. Maybe something like:
Garage - vent cover - hole in the wall - fan - Y adapter - then run one tube from each tent to the Y.
I need to deal with the smell so I’m not sure where the best placement would be for the carbon filter.

[sedin]

Don’t cut your house. why and were do you need to vent this? the pvc might be your stack, help water move through pipes buy supplying air to the line or it is a drain perhaps?

Curious to why you cant just vent out the top of the tents with flex into the room with a carbon filter on the end of the flex.

[sedin]

Seriously love my A.C . I dedicate a single room so no tent there and I build my own tents in other rooms with 2x2 and 1x3 and Panda film but if I was to get a tent AC Infinity has nice tents now. Well priced too.

[sedin]

https://www.youtube.com/watch?v=jm3ygMJx9FQ

this may give you a good idea.p.s Garage walls are meant to keep out deadly carbon monoxide.

[BarefootAndBlazed]

Thanks for that link. I hadn’t seen that one before and it’s a nice, easy to follow presentation.

@sedin

the pvc might be your stack

That horizontal 4" pvc tube is not connected to anything - it is open at each end. I was considering incorporating it into my exhaust plan, but it can remain unused. Is there such a thing as a decorative PVC tube?

I had issues managing humidity last summer. It was my first summer in this house which will be my permanent residence for years to come. While I’m “legal”, a caregiver can grow up to 54 plants at a time for themselves and two patients. I don’t want my house to reek of dank weed when my young nephews come to visit. My concern is that exhausting into the room - a 50 year old Midwest basement with no windows and only one door - won’t be enough to manage smell and humidity. I don’t think CO coming into the basement from the garage is a concern since there would be a strong fan blowing the opposite direction.

I’m liking the simplicity of placing the fan near the exhaust to the garage so it will pull with a tube coming from each tent into a Y. Maybe stick a carbon filter in each tent near the point of exit.

Thanks so much for stopping by. Any other advice is still appreciated!

[Gpaw]

Would putting the carbon filter in the garage help?
Could you bring air in from the living area?

Cheers
G

[BarefootAndBlazed]

Since the house has been a construction zone most of the time I’ve lived here, we have been using the garage for storage and workspace instead of for vehicles. With cars pulled in, I think there would be room for the carbon filter and fan to live in the garage. It might be really close to one of the vehicles. Off the top of my head I think keeping the gear in the garden room would be preferable, but in the garage could work. I’ll need to take some measurements to know how much space the unit will use to know if it will fit easily. I think I’d feel more comfortable having the smell scrubbed before it enters the garage that people walk through…

The one door to enter the garden room is generally left open a bit for air exchange. If I felt the need to keep it closed I could always install a screened vent in the door.

[sedin]

4 inch pipe diameter too small for venting. Your fan goes out and that hole will pull passive air into your house. Control the heat and you control humidity. First take readings of just your basement no grow. See what your up against. Where is your supply air coming from? Do you pay to heat your in house air? or do what should already be done put a hole in the basement lol basements need some kind of venting. Potential for mold and vapor damage is huge even with out the grow.

[BarefootAndBlazed]

@sedin You seem to be very much against exhausting air from the garden room. Am I wrong in thinking that is a common practice? I see plenty of articles and videos about it.

The majority of my basement is finished, livable space with no environmental issues. The one unfinished section where I’m growing wasn’t meant to house 54 hungry plants with the heat generating lights and large quantities of water that are required to keep them happy. Are you saying I need to improve environmental controls in that concrete, windowless space without exhausting the hot, humid, stinky air? I’d like to avoid the cost of running a portable AC like I did last year.

[SubSoilSelections]

Do Not cut up your floor joists. Never cut or alter structural.
There is a way to vent this space without compromising the integrity of your home.
What kind of lighting are you running? What are your temps looking like in the tents as well as outside of the tents?
You should be able to pull off venting into the room the tents are in. A dehumidifier may be needed, but no big deal. Give more info and we can resolve this

[sedin]

He gets it lol Look I have had many too big over-enthused ideas over the years. ex. Almost filled my whole living room with sand so I can feel like I am at the beach lol so i get it. But building code is a good thing. Basements automatically need some sort of venting. Definitely a DIY project if your handy and the info is out there. Lots of strains also don’t really smell. some like crazy. I believe you need to deal with the basement first. Take readings for humidity and temp down there and see how much flex you have and figure it out based on that first. Also, tents incubate humidity some times no tent deals with temp much better. It is not just me there are a million men out there ( and women) who her the words cut into structure and are like Woah wait a min. same goes for garage breach. cold air will settle down any hole. there is always a way. More info, flex can run your air many places. Dryer vent anywhere?

[The_Lazy_Hippie]

Is your house old enough to have a chimney that runs down into your basement? Older homes would have chimneys to vent the furnace out of the house. Over the years furnaces have become more efficient so they have switched to just venting out a 4 inch pipe out a side basement wall. If you have an older home but newer furnace and water heater your chimney might not even be in use right now. Added benefit is your chimney is made to do the exact job of venting air from the basement directly out of the house. Might be worth having a look to see if you can utilize it.

[ChemicalDependant]

I don’t have near 54 only 4-5 at a time. But I vent into the rest of the basement (it’s all unfinished) and smell isn’t an issue. You can mildly smell plants in the basement, but nothing upstairs. I think adding a carbon filter for smell, you’d appreciate the free heat venting inside (some of the year anyways).

[BarefootAndBlazed]

There is no chimney. The laundry, hot water heater and furnace are all 20-30 feet away on the opposite side of the basement, a couple rooms over.

The garden room is approximately 10x18. There is the one door to enter the room and no windows. The nearby bathroom has a fan that exhausts via the right side of the garden room but it is a mere 2.5" diameter on the outside (4" in the basement but only 2.5" upon exit from the house). Modifying that hole would require chipping at the foundation which I won’t do.

I suppose it does no harm to acquire the equipment I need and set it up without exhaust to see how the environment changes as we move into summer.

Without additional steps I’ve seen readings in the tents above 90° and 80% humidity. I’ve kept the one door ajar with a powerful fan to bring in fresh air, and have run humidifiers (in the coldest part of winter when I was running the furnace without the heat pump), dehumidifiers (when moisture was the issue but not temperature), and a portable AC (to combat both high temps and humidity). Ideally I’d like to keep this door closed and locked since I’m no longer working from home and state law requires the grow to be secured.

[sedin]

More secure than a front door to your home? or basement door? Not sure of your laws.

a pick-up fan might just get you the 30 feet to your dryer.

Perhaps one corner is too much can you put another tent elsewhere?