Thread: Anything that can be done here?

That does look like a nice little shed.

3x4 by, I will estimate 2.7m, makes it about 32.5 m^2.
To get 20 room air changes per hour you will need ~650 m^3 per hour.

This flow could be generated by two standard bathroom exhaust fans.

The best location for these would be up high on the back wall or even in the roof.
You would need to keep one of the doors ajar by about 100 mm to enable air to circulate

Except for when using machinery (not the DP), dustier making power tools, and the shop vacs (they can make more fine dust than they pick up) and for ~20 minutes thereafter this would allow you to operate without a mask.

Two fans could be handy because you could run both for say 20 minutes after the dust making and then drop that to one after that.

Another thing that would improve air quality is if the shop vacs have clearly defined air exits then vent these outside the shed. If not then maybe consider enclosing them in a mobile or fixed enclosure and venting the enclosure outside via 50 mm flexy.

The other thing to consider would be 50 mm ducting for the vacs with 3-4 ports in teh ducting to connect the vacs up to and then vent the ducting outside.

Bathroom fans... I can do that! Why didn't I think of that? Thanks a million Bob

I might get a particle counter to see what the situation is generally, and with the shop vacs specifically but yes I can definitely build an enclosure or vent them outside, maybe a bag somewhere under those trees on the right.

On to the drawing table

If you want something more robust than a bathroom exhaust fan (I don't believe their flow rates anyway) then something like this from the "grow your own" community is going to move more air, very quietly, for a long time. They cost much more than bathroom fans but are designed to run 24/7 so they will last.

https://www.ebay.com.au/itm/6-INLINE....c100005.m1851

Look around as there are a wide range of sizes available.

Strange looking... I will investigate it, thanks. It looks like it's meant to hang from the ceiling?

I was thinking of something like this:
https://www.fansonline.com.au/commer...-shutters.html

They have flow rates from 780m/Hr ($215) to 2280m/Hr ($355) allegedly.

Originally Posted by Spyro

Strange looking... I will investigate it, thanks. It looks like it's meant to hang from the ceiling?

It's meant to hang inside a rectangular/square opening and then you baffle round the fan with some ply etc.

I was thinking of something like this:
https://www.fansonline.com.au/commer...-shutters.html
They have flow rates from 780m/Hr ($215) to 2280m/Hr ($355)

Avoid anything with any form of shutters or grille in front of them. If you get one with these - remove them, and if you are worried about the weather coming in fit a small plastic or sheet metal canopy across the top/sides of the fans

Those fans are axial fans which are notoriously inefficient and is why most bathroom fans don't move much air. I can tell just by looking at those fans that the gap between the blades and the housing is too large and it won't pull the claimed flow rates.
Screen Shot 2018-08-15 at 8.32.40 am.png

An impeller that is fully enclosed or close fitting up against the fan housing will be the most effective. The ideal type of fan is a squirrel cage fan as these move huge amounts of air very efficiently. The grow your own type fans I referred to are kind of a hybrid squirrel cage and DC impeller style fan,

Ok that makes sense.

What do you think of placing 2 fans in opposing walls, one pushing fresh air in and the other one facing the other way and pulling dusty air out?

Originally Posted by Spyro

Ok that makes sense.

What do you think of placing 2 fans in opposing walls, one pushing fresh air in and the other one facing the other way and pulling dusty air out?

Trying to push fine dust is like herding cats - the push ends up spreading the dust into various nooks and crannies. If you want to use two fans make them both suck and put them separated as far apart as you can on the back wall and either put some vents in the wall with the door in it or leave the door ajar.

Ok so the fan arrived today



I got a kit that includes an 8 inch fan (allegedly rated at 1000 cubic m/hour), 5 metres of aluminium ducting and a fan speed controller.
I liked the idea of the ducting because I might just hang the fan somewhere convenient inside the shed and pass only the duct through the wall, we'll see.
I paid $188 for the whole thing incl postage, so I guess that's not a bad price.

The fan itself is not small, and it's not light (about 5.5kg)



It seems well made and it runs fairly quiet. Not sure what's the story with the black hoodie but whatever.

Now to think of a position for it and figure out how to attach the ducting to the fan... tape I guess.
And then make a big hole in the wall

Originally Posted by Spyro

It seems well made and it runs fairly quiet. Not sure what's the story with the black hoodie but whatever.

I think the hoodie reduces the fan housing vibe/noise. Our Hydroponic friends are very keen on that.

The plan was to install the fan today, but because I'm lazy I decided to do a detailed computer plan first with my advanced design software





Basically my problem is that I can't really use the back wall opposite the door or the window because these walls are also the property boundary and that means I'd be venting directly in my neighbour's back yard.
He's a really nice dude and he wouldn't mind, and I understand the pissing in the ocean theorem, but it still seems kind of rude to do that.

So I'll probably do the next best thing which is to tilt the fan towards the center of the shed and vent it in those big trees on the side.
Which is another problem because I can't really work out there, these trees are 10m tall cypresses and there is a massive trunk literally 10cm from the shed wall with a bunch of very thick branches.

So I'm thinking make some sort of a insect mesh panel for the vent, slide it in position somehow, open the wall from the inside and fasten it with bolts from in there.
Having fun with the fan!

Originally Posted by Spyro

So I'm thinking make some sort of a insect mesh panel for the vent, slide it in position somehow, open the wall from the inside and fasten it with bolts from in there.

Is the insect mesh to stop insects getting back into the shed?
If so I would put the mesh on a lightweight (ie plastic) hinged flap on the outside of the shed so that the outgoing air lifts the flap out of the way. If the screen is permanently in front of the outlet it will restrict the flow and clog up with dust etc even further restricting the flow.

Originally Posted by BobL

Is the insect mesh to stop insects getting back into the shed?
If so I would put the mesh on a lightweight (ie plastic) hinged flap on the outside of the shed so that the outgoing air lifts the flap out of the way. If the screen is permanently in front of the outlet it will restrict the flow and clog up with dust etc even further restricting the flow.

I've already made it



I guess I can cut the mesh and go to bunnings to see if I can find something plastic to put on top

Ι didn't find anything that I liked... I'll just leave the mesh on for now until I think of something better.

It's not the insects I'm worried about, it's mostly a family of possums that lives on those trees. I guess I could let them wander in the duct to the fan and back, but I'm concerned they might restrict my airflow
No seriously, that duct is ridiculously thin, they'll just tear right through it.
Chicken wire might do it

Originally Posted by Spyro

No seriously, that duct is ridiculously thin, they'll just tear right through it.

If it's too thin and flops around it will rob air flow and you may be better off replacing it with rigid PVC or stiff flexy.