Help with extractor fan requirements

[Cat]

So, I've just bought a Mountain air carbon filter 4" and it's huge, 43cm length @ 310m3/hr. I'm looking for a quiet fan with budget £300/400. (I'm UK).

My tent is 90 x 90 x 160 cm and I THINK that calculates at the air needing removed (sorry if I'm not very knowledgeable with calculations.) I calculate 0.9 x 0.9 x 1.6 meters x 0.75m and I think this means I need to expel 58.32m3/hr, but I'm not sure. My problem is in two parts:

(1) the 4" fans I am looking at (TD silent) is 57.5cm length, which means it would be too large to fit in the tent along with the carbon filter.... Is it okay to set it up so that the filter is in the grow room and the fan is outside?

(2) Most 4" fans only have a capacity of 250m3/hr, which is lower than the carbon filter capacity.....does this really matter or will it work okay? Should I get a larger fan with a controller instead?

Would be grateful for some advice.....cheers

 

[GeorgeCloney]

@Cat
Is the purpose of the fan for smell or extracting heat in the tent?
For smell, a 4" fan (10cm) will do the job for smell , all depending upon the filter you're using.

I bought a 4 inch fan and (4"x12") carbon filter from Vivosun on Amazon,..it works very well in my 2x4x5 tent.
Consider the filter to work well for smell to last 1 year, or depending on how smelly your grow is ( hope it stinks!!).
(Sorry about my coversions to metric right now), I'm Canadian, so not quite bloke, not quite American with our units of measure).

The advantage to a small fan is noise, and you can always add a second if need be to save money until you prove the setup works.
Option 2 is to get a 6 inch fan and throttle down for noise, increase as needed.

My first fan was inexpensive and you get what you pay for, so the second was of better quality (same size!).
Right now with Covid, buy a decent fan once, cry over the price and be happy for the rest of your grows.

Should this fan fail, what will you do?
Bigger is not better.

edit: as for setting up the fan and filter.
Filter and fan SHOULD BE OUTSIDE THE TENT if possible.
Gives you more room for the lights ,but especially keeps unwanted heat out.
The problem with this is noise.
You can set up to suck from the fan , and blow through the filter ( in to out on the filter).
Physics says, any way you set up will be the same.
And the filter doesn't care about (out to in,...or in to out)...makes no difference...
Hope this helps..


Cheers from Canader

 

[ricky4003]

My tent is 160cm x90cm x 50cm and I use a 5" ruck fan for extraction and there is no room inside for both fan and filter so I have the fan outside the tent. Try and get your fan as close to the filter as possible like stick a sheet of ply on top of your tent and place the fan on it then you will only have a short length of ducting which will make your fan perform better than it would if a long length of ducting was used. Remember using a carbon filter and long lengths of ducting will affect your fans performance so I would opt for a 5" fan which gives more power which you might need to overcome the drain taken from the filter and any ducting runs. If you decide on a later date to use an intake fan then choose a 4" fan .

 

[ricky4003]

It is better if you can get both your fan and filter inside of your tent but if that is not possible then place your filter inside and your fan close on the outside with minimal ducting.Extractor fans work better inside the tent not outside.

 

[GeorgeCloney]

My tent is 160cm x90cm x 50cm and I use a 5" ruck fan for extraction and there is no room inside for both fan and filter so I have the fan outside the tent. Try and get your fan as close to the filter as possible like stick a sheet of ply on top of your tent and place the fan on it then you will only have a short length of ducting which will make your fan perform better than it would if a long length of ducting is used. Remember using a carbon filter and long lengths of ducting will affect your fans performance so I would opt for a 5" fan which gives more power which you might need to overcome the drain taken from the filter and any ducting runs. If you decide on a later date to use an intake fan then choose a 4" fan .

I think this is excellent advice!

 

[GeorgeCloney]

It is better if you can get both your fan and filter inside of your tent but if that is not possible then place your filter inside and your fan close on the outside with minimal ducting.Extractor fans work better inside the tent not outside.

As ideals for noise, yes I fully agree.
In terms of performance...doesn't make any difference inside or out. (Physics growbro).
The advice on keeping ductwork short, yes absolutely. Especially if the setup is inside the tent!, lack of space obviously

Edit: If we wanted to do the math on cubic feet or cubic meters per hour,...
Ingesting air into the filter because of square inches into is bigger than inside the filter to out,...yes better efficiency.
But lets also consider noise and setup.
In the end, both will work very well.

@ricky4003 ( didn't mean to kick you in the nuts on this one),...everything you said is perfectly true...

 

[ricky4003]

Maybe a fan controller is something that you need and I would recommend the GSE fan controller as it is a great piece of kit!

 

[Cat]

@Cat
Is the purpose of the fan for smell or extracting heat in the tent?
For smell, a 4" fan (10cm) will do the job for smell , all depending upon the filter you're using.

I bought a 4 inch fan and (4"x12") carbon filter from Vivosun on Amazon,..it works very well in my 2x4x5 tent.
Consider the filter to work well for smell to last 1 year, or depending on how smelly your grow is ( hope it stinks!!).
(Sorry about my coversions to metric right now), I'm Canadian, so not quite bloke, not quite American with our units of measure).

The advantage to a small fan is noise, and you can always add a second if need be to save money until you prove the setup works.
Option 2 is to get a 6 inch fan and throttle down for noise, increase as needed.

My first fan was inexpensive and you get what you pay for, so the second was of better quality (same size!).
Right now with Covid, buy a decent fan once, cry over the price and be happy for the rest of your grows.

Should this fan fail, what will you do?
Bigger is not better.

edit: as for setting up the fan and filter.
Filter and fan SHOULD BE OUTSIDE THE TENT if possible.
Gives you more room for the lights ,but especially keeps unwanted heat out.
The problem with this is noise.
You can set up to suck from the fan , and blow through the filter ( in to out on the filter).
Physics says, any way you set up will be the same.
And the filter doesn't care about (out to in,...or in to out)...makes no difference...
Hope this helps..


Cheers from Canader

Hey! Thanks for the reply. Yes, its really for the smell and I guess also the heat come summer. I'm wondering if I can buy a converter to connect a 5 inch fan to the 4" carbon filter. I just need to make sure the fan is quiet enough at nighttime. I'll have a look on Amazon for the vivoson but I've got a feeling it won't be available in my neck of the woods. Cheers for the advice bud.

 

[Cat]

It is better if you can get both your fan and filter inside of your tent but if that is not possible then place your filter inside and your fan close on the outside with minimal ducting.Extractor fans work better inside the tent not outside.

Hi mate, thanks for the reply. Yes, I'd prefer the fan inside the tent. Its just that the carbon filter is huge even though it's only 4" it's very long.

 

[Cat]

Maybe a fan controller is something that you need and I would recommend the GSE fan controller as it is a great piece of kit!

That controller looks awesome and I will definitely look into that. Do you use that? Many thanks for your advice mate