Filtration question. Opinions/explanations please.

[Nick Clayton]

Has anyone used a whole house fan to make a workshop filtration unit? From a simple CFM standpoint they seem up to the task, but once you get into the physics that I don't understand (performance drop due to adding filters) how would they stand up? Thank you for the help.

Cheers,
Nick

[Kent Fitzgerald]

Nick, I don't think it's practical. I just looked up a few whole house fans, and they seem to run 3,000 CFM and up. While the brute-force aspect is appealing, you would need a huge amount of filter area to take advantage of that airflow, and I suspect that kind of velvocity in an enclosed room would be rather disturbing (Lash me to the mast, Mateys!). They also cost as least as much as a manufactured air cleaner unit. So, unless you already have one to experiment with, it's not cost effective.

As to the usefulness of air cleaners in general, I regard them as a distant 3rd line of defense in the war on dust, after (1) effective dust collection at the source and (2) a properly fitting respirator. Air cleaners, IMHO, are mostly a cosmetic solution: they will keep the shop cleaner and reduce dust problems in finishing, but they're not really a health solution while you're working in the shop.

[Cliff Rohrabacher]

The larger squirell cage HVAC fans have the high Delta-P sufficient to push the air through a series of filters getting yout below a micron particle size.

I dunno perzakly what a "whole house fan" is.

[Steve Clardy]

The larger squirell cage HVAC fans have the high Delta-P sufficient to push the air through a series of filters getting yout below a micron particle size.

I dunno perzakly what a "whole house fan" is.


I believe a whole house fan is the ceiling unit that draws air through the house into the attic. Usually a belt driven unit.

[James Duxbury]

Ken A propeller fan does not work against the static pressure of a filter. The efficiency drops right off. You need a squirrel cage blower and they come in all sizes. Pick the pre-filters and final filters first and from them get the specs. This will give you the CFM/Sq Ft and pressure drop. The final filter should be at or below 1 micron. Calculate the volume of your shop and divide it by the number air changes per hour you want to accomplish. Also it is best to build this with the filters on the intake side of the blower. That keeps the blower clean.

Don’t forget the dust has to go past you to get to this thing.

I use a Resp-O-Rator with HEPA filters.

Hope this helps—It is not easy to make one that works.

[Al Willits]

I use a 1/3hp furnace blower assembly, have it mounted on what was the window (now a sheet of 3/4" plywood) and find that more than sufficent for a appox 26x32' garage.
It would take welding smoke/fumes out in short time, and I emagine it would circulate the air inside reasonably quick

Plus it has three speeds on it, which makes it nice.

Al