Exhaust fan size
 

Hello everyone !

What fan size do you use for your exhaust system? I need a new system and was just wondering what everyone else uses.

Thank you :)
Régis

Hi Régis. If you want to do it right, this is the info you need: https://mikeaurelius.wordpress.com/ventilation-primer/

I got my fan from my old furnace when I had it replaced.

The young man pulled the fan out of the housing for me, carted off the rest and even left me the panel that had the wiring diagram on it,

The furnace for this old house is some 100,000 BTUs so this thing is meant to move some air in a hurry.

You might be able to get one free for the asking at a local heating and A/C shop because they have to pay the cost of disposing of the old ones whenever they install a new one.

I am not familiar with the weather in your area but even old A/C units should still have working blowers when they get scraped so its worth looking into.


Everything I have studied says 850 cfm as an absolute minimum and that would be with the torch flame pretty much running right into the suction funnel.

If you are using a horizontal hood you can probably multiply that by four or six times.

If its a barley box ( enclosed on five sides ) you can get away with smaller multipliers but not by much.

Remember that it not just smoke you are trying to move it is also heavier particles that will fall out of the air within something like a one foot radius from the molten glass and collect like flour dust on everything you will wind up touching eventually.

Some of the colorants are very toxic heavy metals like cadmium and lead and such and you really do want to make sure to get those out of the house where the rain can wash them away and dilute them.

I got my in-line fan from Grainger. They have a large selection of fans. I believe the strength depends on the size of your space.

Mine is an industrial centrifugal fan that moves 864 cubic feet per minute through a very short run (40" long) via 10" ducts.

Ceiling mounted. Suspended via threaded rod in all four corners. Wired with an on/off switch mounted to wall. Flip switch and go. For aesthetics, framed and enclosed the sides in drywall and trim.

Carefully calculated the required size before purchase. It is very effective. (You can barely see where the duct exits through green wall in this pic.)