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For airflow would a filter be better placed prior to or after the main fan? Answered

I am looking to build a very simple air filter setup to help reduce dust and cat particles in the air while deep cleaning.  Would I be better off putting the filter on the front side (air out) or back side (air in) of the fan.  I know to keep dust off of the fan itself the back may be better but will i get better air flow with it on the front?  Thanks for any info.


Main fan of what? A vacuum cleaner? (you did say deep cleaning). o_0

Sorry, more detail would have helped. Any fan really but in my setup likely a box fan or some sort of industrial fan. I'm basically looking to remove stirred up dust from the deep cleaning. My wording would be a bit confusing though.

Thanks for clarifying. I would suggest installing a filter to the back of the fan (where the front is the direction of airflow). The reason is to help keep the fan clean (as they tend to get pretty dirty with use). I would also suggest a HEPA filter as they are the best at removing fine particulates.

You can get large HEPA filters (meant for use on a furnace) and then find a box fan of similar size. Most of these filters have just a cardboard frame, so it shouldn't be terribly difficult to trim (if necessary) and to attach it to the back of the box fan (maybe just poke a few holes in the cardboard and secure it to the back of fan with some twist ties). That way it'll be easier to replace the filter down the road. :-)

Thanks for the info. That makes a lot of sense to me. That sounds like exactly what I'm wanting to do. The HEPA is a good idea too as long as it wouldn't be too expensive, Ill look into them at my local stores. Just wanted to make sure I wouldn't lose too much air flow with one option over the other but it seems they are pretty much equal. Also the twist ties are a good idea. i was thinking just duct tape or something but that sounds much cleaner and easier to change. Thanks again.

HEPA filters are more expensive than regular filters. However, keep in mind that the number of months noted on the package is for regular furnace use. I think you'd get much longer time with the filter, since you're not likely to run your fan as often. A regular furnace filter will block larger particulates, but it's not nearly as efficient with allergens and finer dust particles, so I think its worth the additional cost (its the kind of filter used in hospitals).

HEPA air purification system uses high grade filtration technology to control
contaminants. HEPA filters are more expensive than regular filters. High efficiency
air filtration systems help improve indoor air quality. Thanks for the suggestion. http://unitedfilter.com/


Filter goes before the fan. That way if the pipe leaks after the fan it;s only blowing out clean air.

My initial setup will probably not be using any ducting on the exhaust but I will keep this in mind as I modify it for a possibly more permanent situation. Eventually, if it works, I may hide it away for full time use to help with particles in our air.