Air purifiers can be expensive and you've probably seen articles recommending to just put a 20" x 20" x 1" furnace filter on a cheap 20" box fan and POOF! instant cleaner air for not a lot of money. It really does  pretty cheap. There's a problem with this though. These fans weren't designed to be run with a filter. The filter will restrict air flow which will put a higher strain on the motor causing it to use more electricity and in worse cases could be a fire hazard. The higher the MERV rating (cleaning efficiency) of the filter the .You can still have your as long as the filter area is increased to decrease the effect of air resistance. Instead of using one 20x20x1 filter we'll use two 20x25x1 filters which increases the filter surface area over 250%. It's a little more expensive because you're using two filters instead of one but the increased filter surface area also helps the filter last longer before it gets clogged up and we're saving on energy use compared to a single filter.

I can't take credit for the design, I found it via  but I'm using different filters. I recently remodeled my basement and there's a lot of dust (including drywall dust and sawdust) and fumes from paint, cleaners and other building materials. It's an underground basement and mold has to always be a conern too. Because part of the space will be my home theater in the future I plan to get a more expensive air purifier that's smaller and quieter such as this  because it has great reviews, is reasonably priced and the replacement filters aren't that expensive or a or  if I find some extra Benjamins in the couch cushions. air spray pc cleanerBut I don't want to put that in the dusty environment right away because I'll have to replace the more expensive filters fairly quickly because the air is so bad. diy workshop air cleaner

I also don't want to spend the money right now but I do want cleaner air now. So I decided to get things going with a that has filters that not only clean the air of particulates but also. Even after I purchase an air purifier I'll still have an air purifier I can use for other purposes like when I'm painting or cutting wood. Also, don't forget to add more plants to your home. electronic air cleaner clicking/snappingThey're natures air purifiers. Not only do they convert carbon dioxide to oxygen but too! Filtrete Home Odor Reduction Filter, 20-Inch by 25-Inch by 1-Inch, 4-Pack (only using 2 at a time) Cardboard (from the package the filters came in) or oak tag Duct Tape or Clear Cellophane Tape Optional  Plug-in Timer so the fan isn't running constantly without manual intervention. A pair of scissors or utility knife Quick Info About Filters The nice thing about this box fan filter setup is you can use any filters you want.

If you are only concerned about large particles generated from something like cutting wood, you can use cheaper, lower MERV rated filters. If you're worried about finer particles from allergens such as mold, you can use a higher MERV rated filter. To understand more about what the MERV ratings mean have a look at Table 2 on this EPA article on residential air. Filtrete Odor Reducing Air Filters The filtering power of these Filtrete Odor Reducing filters isn't listed on Filtrete's website or on Amazon but I contacted them and found out that these filters have a MERV 11 rating and filter 90% of particles between 1-10 microns which makes them more efficient than the Filtrete Micro Allergen Reduction Filters I've been using in my air conditioning for the past few years. Plus Filtrete packs over 180 grams of activated carbon to help reduce odors. After I go through both sets of carbon filters I'm probably going to switch to the Filtrete Elite Allergen Reduction Filter which does a much better job of filtering small particles.

If odors are a problem I'll get some Cut-to-fit Carbon Prefilters and tape them over top of the Filtrete filters. Okay, enough of the why, now for the how! Step 1: Unbox The FiltersHe's actually describing how to open a cardboard box?!?!?!" The best deal I found for these filters were on Amazon and with my Prime membership (or supersaver shipping) the shipping is free. Plus the packing box is going to be part of the filter so we need to keep in intact. The box is sealed very well. Not only is it taped but the seams are also glued together. To get the filters out of the box I cut the top where it's perforated with a utility knife as shown. Be careful not to cut too deep and damage the filters. Keep the box someplace safe to the side while we continue. Step 2: Hinge Filters Start by taking 2 of the filters out of their plastic wrappers and lay them one on top of the other with the air flow arrows pointing towards each other. With the Odor Reducing Fitlers this means the black, carbon sides will be facing each other.

With the filters lined up, tape one of the short (20") edges of the filters to create a hinge between the two filters as shown. I decided to go with white duck tape so it looks a little nicer but it makes it hard to see in the photos against the white cardboard filter frame. Step 3: Tape Filters To Fan Lay the box fan face down on a flat surface to mount the filters to the back making sure the bottom of the filters are about flush with the bottom of the fan and do not extend past the bottom. Use a strip of duck tape to secure each side to the side of the fan. Cut out one of the large sides of from the cardboard shipping box, place it over the top of the of the filters and secure it with a strip of tape to the top of the fan. Position it so that it's pretty even over both filters but it doesn't have to be perfect. Using a pencil, trace around the filters (while pressing down the cardboard so nothing moves) to mark where the cardboard needs to be cut. Lift the cardboard up (the front piece of tape acts like a hinge) and cut along the lines to trim the sides.