Looking for Ventilation Pro's Opinion

[Supernaut]

Here's a rough diagram of the setup in my basement. I'm looking to possibly use a single in-line fan to pull air into and exhaust both my veg and flowering room. I have a few other ideas as well, but this may be the cheapest set-up. Just wondering if 1 in-line fan can pull air through both of these rooms or if I should set up a fan for each. Thanks ahead of time for any input!

 

[NCDude]

Looking good...

 

[miwa]

I would (according to your rooms position)....i would have a fan for each room...less material...cuts down on things that may go wrong...all and all easier to maintain...just my thoughts

 

[Supernaut]

Miwa, you say a fan for each room. Would I then hook the carbon filter up to my main rooms exhaust and pull air through it and out the chimney?

Like This? --------Room------>----Filter---->------Exhaust Fan----->----Chimney---->

Even though I am growing legally, I don't want my neighbors smelling my dank. Pulling air, rather than pushing through a carbon filter works equally well?

 

[Supernaut]

O.K. Thanks a ton for your input guys.

After considering what you guys have said, this seems to be a good option. I'm thinking I don't really need to exhaust the veg room outside so this should work. (I'd still like to hear/read some constructive criticism though)

I do have another question regarding this set-up though. Would I want the exhaust fan for the flowering room to be in spot C or D?

 

[CannaVince]

Hey naut... Um just thinking if it were me?.... I would hook up both rooms to my 440 Inline 6"...are you drawing your lamp heat through there too?....than that depends....cause of heat....as long as your intake air venting is adequate or equals the pulled air you'll be fine.. Then after it's filtered out you can reroute it outside....so both rooms to a Y--------then Inline fan--------then filter----then vented outside with separate fart fan.......I've got my set like this for yrs and nobody's the wiser.. .....good luck...

 

[Supernaut]

I do plan to vent heat out of my flowering room with this set up. I'm only using a 400w hps set-up and being that it's in my basement and I actually have to heat the room here and there I would think that it shouldn't get too hot. Maybe I'm wrong though. I'm still waiting for my light to get delivered so I haven't set it up to test as of yet.

The veg room is all flouro and cfl lights and does not get hot. It also has a 5' ceiling rather than the 7' ceiling in the flowering room. Overall dimensions are ~ 2.5'deep x 7.5' long x 5.25' high so it will need much less cfm of air coming in and going out.

The outer room is fairly air tight.

 

[miwa]

i would exh flower rm at point c...good setup

 

[CannaVince]

Ok naut sounds good...400 is perfect... I've got the same....So air is coming into those rooms from passive (a)..? From upstairs air?....and how are you getting the final air out of the basement? After it's been exhausted outside the growrooms?...why is it air tight?...if your recycling that air it will still be very warm and will increase your overall temps...bad....it needs to be a perfect circle of venting so to say.....ive never been a filter and ballast inside the growrooms fan...well get her figured out my man...don't want poor circulation and negative presures....

 

[Supernaut]

The intake air is coming from another room in the basement. It's a 6" passive vent. I think I may install a separate one for each room as I have been reading that you need to make sure your intake isn't short on air supply. It's either that or install a ~100 cfm pc case fan there to ensure it's bringing in enough air, I just don't want to have more intake air than exhaust and find myself in trouble. Input?

It's pretty air tight because everything is covered in panda poly and duct taped to prevent any air entering or leaving that I don't want to. I got a 10x100' roll and made as few cuts as possible, 1 seam per room (yes, it was a pain in the ass to hang by myself but I got better as I went). Ceilings and floors of grow rooms are panda poly with seams duct taped as well. Main room has only walls covered w poly with all staples duct taped and duct tape on floor and ceiling to stop any air/light leaks. A little overkill for light leaks since it was dark as hell anyway, but it served as an air leak prevention as well so I went for it. The door leading out of the room has been fitted all around with weather stripping.

Point 'D' on the second diagram I posted is actually a cold air return from upstairs. I will be cutting a 6" hole in it to run my ducting through. The furnace and hot water heater are about 2' outside that to the left. They vent out a chimney (this chimney is separate from my fireplaces). There is an extra 6" hole in that chimney that hasn't been used since ancient times. What it had been used for, I have not a clue. I will be running my overall exhaust to and out of it.

I may have left out a detail here and there. If you have any more questions about it to ensure a proper answer, let me know.

Thanks guys! My ventilation is probably the thing I have spent the most time pondering over and questioning what will work best.

 

[Hogdady]

Some things to consider...

Ventilation is heat relevant. If you use HID lighting, your temps will be elevated, requiring more ventilation to aid in cooling.

You will need to move the entire volume of air in the room at least very 1-3 minutes. Don't know how high your ceiling is, but if it's 8', your room volume is 1248 cubic feet.

With elevated temps, you may need to move 2-3 times the room volume per minute.

If you use a passive intake, it should be at least twice the size opening as your exhaust outlet size.

 

[Supernaut]

Yes, the entire room's volume is large like you mentioned. However; the rooms I built that need exhausted are only at 378.4375 cubic feet total for the two of them.


It was mentioned that running both room exhausts to a 'Y' with a fan behind that to exhaust outside would work. I was thinking that I want to try and make the cfm moving out of each room different, having more move from the flowering room since it has about 2.5x the cubic feet of the veg room, plus HID lights. After thinking about it, I thought that there could be 2 ways to do this.

1- Make the section of duct hose from the veg room longer than the one from the flowering room by about 40-50%. The air traveling farther should reduce the pull on that room, correct?

OR

2- Run a 4" line from the veg room to a 4-6" reducer to the Y.

Either of these would effectively reduce the pull from the veg room and increase the pull from the flowering room if they used a shared fan, wouldn't it?

I was leaning more towards the 4-6" idea there.

Another question:

Since I'm trying to cut costs down a bit, I was thinking about getting your run of the mill, 6" ~$30 in line fan. The ones I've looked at move about 250 cfm. Thats a bit low so I was wondering what someone might know about piggy backing 2 of them. I haven't been able to find a whole lot of information on doing this, but from what I understand, I could increase airflow a bit or at the very least it would boost it to keep the cfm up when dealing with bends and corners and what not.

Picture something like this:

Flowering Room------> Carbon filter-------> 6” Inline Fan-------> ~5' of 6” flex ducting------> Y------> 6” Inline Fan-------> ~15' of 6” ducting to chimney.

The veg room would tie into the Y like this:

Veg Room------> ~5' of 4" flex ducting ----------> 4-6" Reducer------> Y

If you guys can think of any pros or cons to this, please let me know.

Thanks a ton for taking the time to read this. I am a bit of a perfectionist, I want to get it right the first try. I will leave room to expand so I can add stronger fans later, but don't want to revamp the entire system because it isn't done properly.

 

[Supernaut]

That's a great idea, I totally overlooked that option. It would cost a few extra bucks, but I could easily get the airflow exactly where I want it.

Thanks Scratch.

Any other ideas?