Ventilation in 2x4x5 tent

Jahredi · Oct 27, 2019

Hey hey! Back with another question everyone

I have a 2x4x5 tent and I’m trying to decide the best way to set up ventilation. I have 2 AC Infinity Cloudline T4 fans. Rated at 200 CFM each, and one carbon filter rated at 205 CFM. Trying to decide if I should do passive intake > carbon filter > 1 exhaust fan; passive intake > carbon filter > 2 exhaust fans connected by T fitting; or 1 active intake fan > carbon filter > 1 exhaust fan. Or any other ideas!

How will the T fitting affect the CFM power of each fan. I’m wondering if it could result in the suction from one fan having a negative effect pulling against the intake of the other fan... I’m no HVAC expert but I don’t see how the fan can know which port to pull from. In effect, it seems like it would pull from whatever was in front of it, which would be the carbon filter and the intake of the second fan. Seems like it might be ineffective and bad for the fan motors with a T splitter

Here’s a chicken scratch drawing I did...

oldskol4evr · Oct 27, 2019

i run and fan filer combo for intake and another for exhaust,dial controler in to take suction from tent,wide open exhaust and then i stop the suction from being as bad with the intake,i have both filter and fan for intake outside the tent running into the 4 in hole in bottom of my tent so filter outside the tent is bringing in room air from outside ,im in a utility room going outside,anyway filter gets dirty pretty often i just take air and blow it out and move on

MIMedGrower · Oct 28, 2019

I only needed a 200cfm inline fan and carbon filter with passive ventilation intake through 4 4” flexible pcv pipes with black filter foam on each end for lightproofing.

Even exhausting out the room into the living room with room temperature passive intake i could keep a 400w mh/ hps or a 315lec in the mid to high 70’s.

This was in a 3x3x6 tent but close enough in square footage to yours for cooling comparison.

Dis i mis something. Why would you need a T and 2 filters or extra fans?

Jahredi · Oct 28, 2019

MIMedGrower said:
I only needed a 200cfm inline fan and carbon filter with passive ventilation intake through 4 4” flexible pcv pipes with black filter foam on each end for lightproofing.

Even exhausting out the room into the living room with room temperature passive intake i could keep a 400w mh/ hps or a 315lec in the mid to high 70’s.

This was in a 3x3x6 tent but close enough in square footage to yours for cooling comparison.

Dis i mis something. Why would you need a T and 2 filters or extra fans?

Nope! Not missing anything MIMedGrower. I’m just polling how others would set it up. First time tent grower here.

As you can see in my beautiful drawing, I have only the one set up currently, and feel like it’s fine. I was just wondering: could I use them both? How? And would there be any benefit? Drawback?

Just trying to build my understanding of how this all works more so than I am looking for a “correct” answer.

Still curious about how two fans on a T don’t fight each other. I don’t feel like it would work anyway. It seems that each fan is going to pull from anything before it in the line, and on a T, that would mean the other fan

MIMedGrower, do you run your 200 CFM fan full out 24/7 in the 3x3x6?

BigCube · Oct 28, 2019

I run negative pressure in my tents.
Exhaust fan and carbon filter. No intake fan. Not sure why 2 fans would even be an option.

MIMedGrower · Oct 28, 2019

Jahredi said:
Nope! Not missing anything MIMedGrower. I’m just polling how others would set it up. First time tent grower here.

As you can see in my beautiful drawing, I have only the one set up currently, and feel like it’s fine. I was just wondering: could I use them both? How? And would there be any benefit? Drawback?

Just trying to build my understanding of how this all works more so than I am looking for a “correct” answer.

Still curious about how two fans on a T don’t fight each other. I don’t feel like it would work anyway. It seems that each fan is going to pull from anything before it in the line, and on a T, that would mean the other fan

MIMedGrower, do you run your 200 CFM fan full out 24/7 in the 3x3x6?

As long as the house temp is below 72 degrees farenheight i run on high to keep the tent under 76. If its colder than that and it is all winter i use the speed controller to dial down the fan speed to keep the tent warmer.

The 315 took more fan speed than the 250 watts of t-5 flourescent tubes i use now for veg.

MIMedGrower · Oct 28, 2019

BigCube said:
I run negative pressure in my tents.
Exhaust fan and carbon filter. No intake fan. Not sure why 2 fans would even be an option.

I said that too but honestly I use intake fans for my flower room to blast ac from the lung room next door in there.

And intake fans do help the exhaust fans work better. But they need to be slower and less powerful than the exhaust to keep negative pressure.

But for a 2x4. Not needed like you say. Small tents work great with passive intake.

I use 2 exhaust fans for my room too. One after the carbon filter and one to move the exhaust a distance to the chimney.

BigCube · Oct 28, 2019

For sure. I guess to me, if you need an intake fan to help your exhaust fan, you bought the wrong exhaust fan

I always rely on my home temperature as a baseline. Being a modern house, I have heat and ac. So I dont have to worry about my intake temps. Also exhausting in to the house helps with the heating costs in the winter summer I vent outside.

Jahredi · Oct 28, 2019

BigCube said:
For sure. I guess to me, if you need an intake fan to help your exhaust fan, you bought the wrong exhaust fan

I always rely on my home temperature as a baseline. Being a modern house, I have heat and ac. So I dont have to worry about my intake temps. Also exhausting in to the house helps with the heating costs in the winter summer I vent outside.

Sounds good! Thanks for the input. I feel confident leaving my set up how it is, now. One fan, passive intake = golden.

But hypothetically, let’s say I needed a higher CFM exchange rate for whatever reason....

Could this be achieved by putting two fans on a T connector to the same carbon filter? Would that double the CFM exchange rate or would they actually fight against each other?

I realize buying a bigger fan would be the easiest solution. Just curious if there was a solution using the gear I have on hand leftover from a different application.

MIMedGrower · Oct 28, 2019

BigCube said:
For sure. I guess to me, if you need an intake fan to help your exhaust fan, you bought the wrong exhaust fan

I always rely on my home temperature as a baseline. Being a modern house, I have heat and ac. So I dont have to worry about my intake temps. Also exhausting in to the house helps with the heating costs in the winter summer I vent outside.

I vent out the chimney in summer amd under the living room floor in winter.

And i needed more fans because my room really calls for 8” fan but i only made a 6” hole and didnt want to cut more of my house up. And its a long run to the chimney for a 6” fan.

I use 2 intake fans one for either side of the room

MIMedGrower · Oct 28, 2019

Jahredi said:
Sounds good! Thanks for the input. I feel confident leaving my set up how it is, now. One fan, passive intake = golden.

But hypothetically, let’s say I needed a higher CFM exchange rate for whatever reason....

Could this be achieved by putting two fans on a T connector to the same carbon filter? Would that double the CFM exchange rate or would they actually fight against each other?

I realize buying a bigger fan would be the easiest solution. Just curious if there was a solution using the gear I have on hand leftover from a different application.

No. The cfm would be the same unless you size up. How far and efficiently you can move the air is what more same fans increase.

Jahredi · Oct 28, 2019

MIMedGrower said:
No. The cfm would be the same unless you size up. How far and efficiently you can move the air is what more same fans increase.

I get it now. Thanks MIMedGrower! If you have to move the air far, you put another fan down the line.

MIMedGrower · Oct 28, 2019

Jahredi said:
I get it now. Thanks MIMedGrower! If you have to move the air far, you put another fan down the line.

Yes. They also make cheap duct booster fans for that.

king_of_nothing · Nov 13, 2020

MIMedGrower said:
No. The cfm would be the same unless you size up. How far and efficiently you can move the air is what more same fans increase.

Pardon me if I am wrong, but I don't think this is correct. @Jahredi wants to connect through a T joint. That's a parallel connection. Parallel connections add up. If it would be in series it is a different story and I think that your answer would be right in that context.

As an example take a look at (this explanation).

MIMedGrower · Nov 13, 2020

king_of_nothing said:
Pardon me if I am wrong, but I don't think this is correct. @Jahredi wants to connect through a T joint. That's a parallel connection. Parallel connections add up. If it would be in series it is a different story and I think that your answer would be right in that context.

As an example take a look at (this explanation).

I thought we were past the t joint idea but you are of course correct.

Ventilation in 2x4x5 tent

Ventilation in 2x4x5 tent

Jahredi

oldskol4evr

MIMedGrower

Jahredi

BigCube

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BigCube

Jahredi

MIMedGrower

MIMedGrower

Jahredi

MIMedGrower

king_of_nothing

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