new rooms ventilation help please

[Organic joe]

Ok so I just built my mom/veg room
It is 3.5x3.5x7 im going vert and im not sure how many cfms I need to keep it cool
I'm using a 400w mh for veg
I read through ventilation 101 several times but don't understand how to figure it out

Where is he getting cfm=3.16*watts?

I have 85.75 sq ft
Now I divide that by 3 changes per minute and come up with 28.58 what do I do next?

I also have a 4x8x6 flower room with 2x400w hsp and a scrubber but not sure on the size of fan needed

Could someone please help me understand how to calculate this stuff
Any help is greatly appreciated
Oj

 

[Ichabod Crane]

Most vert guys shoot for an air exchange about twice per minute.

Your room is 3.5 X 3.5 X 7. so this room has a volume of 85.75 cubic feet. If you go with a standard vert set up you double this to get 171.5 cubic feet. So you need a fan that has a volume of at least this.

You will also need to have a intake to pull fresh air from.

For the larger room you need a fan rated at 384 cubic feet per minute.

 

[Organic joe]

awesome thank you for.your help..

So just to clarify I take LxWxH
Get the total and then multiply that by how many changes per minute and I have the total cfm?

In my case 3.5x3.5x7=85.75x2(changes per min)=171.5cfm

Thanks again your help is greatly appreciated now I can get a new fan and get these temps down some

 

[Cali MedPatient]

BTW They make tubes for cooling vertical lights also.

 

[Ichabod Crane]

awesome thank you for.your help..

So just to clarify I take LxWxH
Get the total and then multiply that by how many changes per minute and I have the total cfm?

In my case 3.5x3.5x7=85.75x2(changes per min)=171.5cfm

Thanks again your help is greatly appreciated now I can get a new fan and get these temps down some

Yes double the cubic feet of your room to size your fan. More is better. Make sure you have no dead spots in your room. Bring the cool outside air in on the opposite side of the room. Also get you exhaust as close to the top of your light as you can, that is where the heat is most concentrated at.

 

[Organic joe]

Yes double the cubic feet of you room to size your fan. More is better. Make sure you have no dead spots in your room. Bring the cool outside air in on the opposite side of the room. Also get you exhaust as close to the top of your light as you can, that is where the heat is most concentrated at.

thanks alot ichabod I appreciate the help as soon as I get my computer fixed I'll post some pics of what I have done so far...
I just need to get a bigger fan other than that itsndone and plants are vegging so far they are loving the vert
now im ready to build the flower room
Thanks again for your help guys