
How to Build a Do-It-Yourself Fan/Filter Room Air Cleaner
using a 20-inch Box Fan and a high efficiency air filter
Build for ~ $40 to clean the air in a small to medium sized closed room.
Download our handy 2 page guide HERE.
using a 20-inch Box Fan and a high efficiency air filter
Build for ~ $40 to clean the air in a small to medium sized closed room.
Download our handy 2 page guide HERE.
MATERIALS:
ASSEMBLY:
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Check out or handy short video - everything you need to know to make a boxfan/filter in just over 2 minutes!
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WARNING: Box fans – if an older model or used incorrectly – can ignite and start a house fire. The most common cause of fires is the motor locking up under load and overheating. You can prevent this if you:
Now you know the risks! We tested several brands of new box fans with filters attached, as described here, and found them to operate at or below their maximum design operating temperature when they are clean and well-maintained.
- Use a newer fan equipped with a fused plug. These are not 3 prong, just slightly larger. All fans sold after ~2012 will have this.
- Keep the fan and motor clean (lint and dirt can cause overheating and catch on fire)
- Keep curtains and loose clothing away from the fan. If the fan does not start quickly and run smoothly do not use it.
Now you know the risks! We tested several brands of new box fans with filters attached, as described here, and found them to operate at or below their maximum design operating temperature when they are clean and well-maintained.
A few details worth knowing
In order to give individuals an affordable DIY option to clean indoor air, especially during wildfire smoke season, we worked with Tom Javins, our local mechanical engineer and consultant, to ensure these are safe! What we have learned from our research and testing: PM2.5 and ultrafine particles can be removed from the air with a DIY room air cleaner. It is most effective with new electrostatic filters having a MERV 11 to MERV 13 filter rating. Equivalent ratings are FPR 10 and higher and MPR 1500 and higher. Change the filter when it changes color to gray or at the filter manufacturer’s recommended time. New electrostatic filters work best for the really small particles that are the most harmful to breath. One filter testing company recommended changing the filter every two weeks for best ultrafine particle capture. A DIY-room air cleaner with a new filter is about as effective as a small or medium sized commercial room air purifier, with a comparable Clean Air Delivery Rate (CADR) based on airflow and the E1 (0.3 to 1 micron particle size) efficiency. The fan motor life is rated for 20,000 hours of continuous operation (24/7) in a room with 104 F ambient temperature. As the air temperature nears 100 F the motor may stop working because the motor is over the safety cutout temperature, this may happen at a lower air temperature if the motor not clean, worn or damaged. Using older box fans is not recommended as they are more likely to catch fire. The more it runs the cleaner the air Abbreviations:
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Tom Javins explains the variety of air filters in this 3 minute video!
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