Intake vs Exhaust.

[augusto1]

When two fans are installed, one for Intake and one for Exhaust which one need to be biggest and for what different? I being reading about it but there are a lot of confusion about it.

Thanks In Avance.

 

[Twitch]

you do not need an intake fan, you should always use a passive intake....

 

[Voidling]

If a passive intake is used, it should be two times the surface area of the exhaust.

If an intake fan is used, then I would make it less than the exhaust fan.

You want more air being pulled out through your filter than is being pushed into your cab so that it has negative pressure. With negative pressure all air exits through the filter.

If the intake pushes more air in than the exhaust pulls out, then smelly air is pushed through cracks, seams, ect.

Remember that a fan rating is how much it blows when unobstructed. When you add a filter it blows considerably less air.

 

[twostrokenut]

Really? What if you want to hepa filter your air and your space isn't air tight? How would a passive intake help that?

 

[ScoobyDoobyDoo]

In some cases you do need an intake fan. If this is the case then your exhaust fan should be stronger to create negative pressure in your room.

 

[a mongo frog]

you do not need an intake fan, you should always use a passive intake....

why do u state this? please explain. why should one always use a passive intake?

 

[augusto1]

If a passive intake is used, it should be two times the surface area of the exhaust.

If an intake fan is used, then I would make it less than the exhaust fan.

You want more air being pulled out through your filter than is being pushed into your cab so that it has negative pressure. With negative pressure all air exits through the filter.

If the intake pushes more air in than the exhaust pulls out, then smelly air is pushed through cracks, seams, ect.

Remember that a fan rating is how much it blows when unobstructed. When you add a filter it blows considerably less air.

will be fine to have like intake 200 cfm and exaust 400 cfm ?


Thank You

 

[alwaysgreen420]

Yes

Sent from my SCH-I545

 

[Voidling]

Probably. Depends how well your fan pulls/blows air through the filter. If you feel air through cracks or seams, or if your room smells you can get a throttle to turn down the intake fan. When throttled down they aren't so loud, though hardly matters if you're running another one

 

[Cascadian]

If you are growing in Panama up to middle America you will probably need an intake fan at a lower CFM than your outtake and depending on how far south might need A/C. If you are in Canada growing in a garage you might want to have a passive intake that is equal or smaller in size than the outtake.

Long way of saying it depends on the ambient air temp IMO. Adjustments are needed depending on the environment you are growing in.

What size is your grow room/cabinet/tent? What light are you using, ambient temps etc?