Ventilation duct size

I recently purchased a Vortex 6" Inline Fan. I'm debating on drilling a 6" outlet vent or adding a reducer and bumping it down to 4". The 4" is a bit safer since I'll be going through cinder block. Better structural integrity. Anyone have any input?

I think it's really up to you whether or not you want to drill a 6" hole vs a 4" hole, but you should know that the Vortex fans aren't air compressors, so a reduction in your outlet port size will directly translate to a reduction in flow capacity. You spent the money on a 6" fan, why not get 6" worth of airflow?

What is the cfm?

Well Vortex is a brand name, so a quick search on google turns up an advertised 449CFM, but of course after ducting and various twists and turns on the outlet you can probably expect about 350-400CFM.

BudzAndSudz said:

Well Vortex is a brand name, so a quick search on google turns up an advertised 449CFM, but of course after ducting and various twists and turns on the outlet you can probably expect about 350-400CFM.

Click to expand...

They have two different 6" models, the VTX600 (452cfm) and the VTX600L (235cfm). Looking at the graph on their website, we would need to know duct length and how many elbows you need to use. The VTX600 is 452cfm @ 0" static, but it is only 169cfm @ 1.5" static. The VTX600L is 235cfm @ 0" and 30cfm @ 1.5".

**Vortex 6" 449 CFM, 1.2A, 136w

I plan on running a straight outlet line about 4'

I thought I could estimate the static pressure, but i can only estimate the friction loss, which the website gives you based on the static pressure. As far as I can tell, the static pressure must be measured. Necking it down to 4" will greatly increase the static pressure, which will greatly decrease the cfm output of the unit.
I work for a HVAC contractor and we routinely put 7" through block walls with no issues (code or otherwise). You just need to make sure the block isn't poured solid.

I think I came up with a solid plan to prevent the block from shattering. I'm going to drill a pilot hole in the block, then fill it with 'Great stuff'. After the great stuff has cured, I'll use a 1/2" bit to drill a 6" circle and use a masonry chisel to knock it out. Thoughts?

You might be able to rent a 6" carbide hole saw from a local tool rental company. That should greatly reduce your chance of shattering the block.