Thread: Best Wall Exhaust Fan

Look up hydroponics exhaust fans on ebay.

Single axial fans that look like this
Screen Shot 2021-11-13 at 3.48.21 pm.jpg
Wont be as efficient or as quiet as those with a built in cowling around them like this
Sometimes called centrifugal fans.
Screen Shot 2021-11-13 at 3.48.53 pm.jpg
Of course you will pay a bit more.

Claims about the ability of simple axial fans to move air should be taken with a pinch of salt whereas the otcentrifugal fans will be closer to their true rating.

For fine dust ventilation you should target between 10 and 20 room changes per hour so a 80 m^3 shed needs between 800 and 1600 m^3 of extraction per hour.

A typical 10" decent centrifugal fan should deliver about 1000 m^3/hr.
Depending on the fan an 8" centrifugal fan is going to be struggling to reach the 800m^3/hour.

The alternative would be to get something 2 x 6" centrifugal fans, or say 2 or 3, 10" bathroom (axial) extractor fans and remove the grilles to increase the air flow.

I got 2 of these from Bunnings.

Blauberg 150mm White AERO Wall / Ceiling Exhaust Fan - Bunnings Australia

They work quite well for a hobby workshop.
They open the hall door if just pushed to.
I put them on before I start a dusty job, then leave them on for a while after I finish making dust.
I mostly use in conjunction with my dusty extractor, except for jobs like painting etc, they quite effective in reducing fumes.
The price seems to have increased significantly though.

The Blauberg 150mm fans are rated for 309 m^3/hr and like I said I'd be taking that specification with a pinch of salt and would discount the airflow by 30- 50%.
So to reach the OPs minimum requirement of around 800 m^3/hr , ~4 of them would be needed.
Fewer fans will still extract fine dust but it will just take longer hence increasing air exposure.

If you want to use bathroom fans I suggest something like this one although they are not Exactly cheap.
Deta 250mm High Capacity Exhaust Fan - Bunnings Australia
Two of these would probably get to 800 m^3/hr

Whatever you do I recommend removing the grilles as they really restrict airflow.

Looking at the centrifugal fans on ebay they seem to be designed to be mounted in ducting. Can you mount them in a wall/ door/window like an axial exhaust fan and if so whats the best way to do it?

Originally Posted by Dave.w

Looking at the centrifugal fans on ebay they seem to be designed to be mounted in ducting. Can you mount them in a wall/ door/window like an axial exhaust fan and if so whats the best way to do it?

Cut a square hole in the wall slightly bigger than the fan.
If you plan on framing up the hole with a timber architrave allow extra for this.

Cut a square piece of 12 or 18 mm ply to cover the hole (and architrave if you use one.

Cut round hole in the ply for the fan.

Mount fan on ply, and then ply on wall.

BobL and others,

What about a fan like this:

DETROIT Industrial Floor Fan 500mm FANFLOOR | Total Tools

…and take it out of the frame and mount in the wall of shed (using some ingenuity)?

chris

Originally Posted by cparker88

BobL and others,

What about a fan like this:

DETROIT Industrial Floor Fan 500mm FANFLOOR | Total Tools

…and take it out of the frame and mount in the wall of shed (using some ingenuity)?

chris

We have one of those at the Timber yard - its very good at rearranging the dust in the shed .
It's an axial flow fan so it's not very efficient and nowhere near the claimed flow.
Its also pretty noisy so a PITA for those times when you want some peace and quiet.

If you do mount it in a hole in the wall the efficiency can be improved by minimising the gap around the edge of the hole between the hole side and blades.
Unfortunately this will make it even nosier.