With allergens, diseases, odors and dust building up during the winter months, there are many good reasons to consider getting an air purifier for your home to improve indoor air quality. While there are impressive air purifiers you can buy with lots of smart techniques, they can be expensive, and you may not want to drop hundreds of dollars on a new appliance.
Fortunately, there is a homemade, do-it-yourself (DIY) option to consider – one that is both affordable and effective. All you need is a box fan and some traditional, replaceable HVAC filters. Let’s dive in to show exactly how it’s done.
A reliable box fan: If you do not already have a box fan, you can find affordable options for around $ 20 to $ 40, such as this Comfort Zone model. Make sure it is about 20 inches high, a standard standard for box fans. A model with a timer is nice, but not required (or you can just connect it to a smart plug).
A package with HVAC filters, also 20 inches: You can find them in any department store or order them online. We suggest that you get at least one four-pack for this project. Remember to choose the right size. Extra features like activated carbon are nice, but not necessary. Examine the filter̵7;s MERV (Minimum Efficiency Reporting Value), which is a number up to 20 that indicates the size of particles that the filter is classified to capture. A filter with at least a MERV 13 rating is perfect because it is rated to capture smaller particles (such as certain bacteria and viruses).
Four-pack MERV 13 filters:
A carton and scissors / box cutter: The box should also have sides that are at least 20 inches high and wide, but otherwise all spare cans should do. If you order a fan or filter online, the box they come in should work well!
Duct tape: It is quite easy to find tape online or in the store.
Step 1: Tape the filters
You can skip this step if you want to make a simple air filter with a filter. All you need to do is attach the filter to the back of the fan with the arrows facing the back of the fan.
However, the most efficient DIY air purifier uses two filters at the same time for better airflow, and it is not that complicated to set up. If you prefer to use this larger installation, start by taking two of the filters you purchased and unpacking them.
Air filters like these will have arrows on the sides that show which way air should flow through the filter. Place your two filters together with the arrows pointing at each other. Now use the tape to tape a 20-inch side of the two filters together to form an angle.
Step 2: Connect the filter to the fan
Let’s talk more about your air purifier.
Design 1: Use a filter for a simple DIY fan cleaner:
As we mentioned above, some just tape the filter to the back of the box fan and call it a day. This is good – air enters through the filter on the back of the fan and then exits through the front of the fan. If you want to do it this way, just make sure the filter arrows are facing the back of the fan.
Design 2: Use two filters for a triangular DIY air purifier:
Having a filter lying directly against the fan can obstruct the air flow, which does not use the filtration in the best way. That is why, if you do not mind any extra steps, we recommend the installation of two filters. The Tom Builds Stuff blog has a great example that shows how this works.
As you can see, place the other 20-inch sides of the two filters on either the side or back of the fan and tape them in place. It does not take much more work, and with greater air flow through two filters, the DIY cleaner is much more efficient. The filters may not fit perfectly, but a little tape can easily solve any problems at the edges.
Design 3: Use four filters for a box of DIY air purifiers:
Some people even go the extra mile to create a four-filter setting, place the fan on top of the filters, and connect the filters to each other and to the fan with tape.
Step 3: Trace and cut out cardboard
This step is unnecessary if you go with the design with a filter, as you can simply attach a 20-to-20-inch filter to the back of a 20-inch drawer fan.
But with the triangle cleaner, you have to cover these additional gaps, so the fan actually sucks air through the filters themselves. This is where your cardboard comes in.
Place your cleaner on the side of the box and cut or trace it to create a cardboard triangle that comfortably fits the air cleaner’s gap. Use this triangle to create a mirrored piece of cardboard for the other side as well.
Step 4: Tape the cardboard to create a seal
Now take out your tape again and seal the edges while attaching the cardboard to the top and bottom of your DIY cleaner. Now the fan must draw air through the filters as it goes. A single strip of tape around the edges should be fine, but you do not want any gaps or cracks that affect efficiency.
Now you are ready to set up your air purifier in a central location in your home.
Step 5: Replace filter as needed
A typical HVAC filter is designed to be replaced every two months. Over time, these filters will become quite dirty and clogged with dust. With a two-filter or four-filter setting, the filters can be a little longer, but you should still keep an eye on them. If they start to look dirty, it’s probably time to quickly disassemble and replace them with new versions so that the cleaner works optimally.