A room air cleaner is a portable, electric appliance that removes fine particulate matter from the air. This is important, both in the summer and in the winter, for those with allergies living in dusty environments or with pets.

Problems With Typical Air Cleaners

The problem is that typical air cleaners are either too small to have much effect – delivering less than 50 cubic feet per minute (cfm) of cleaned air – or are so large that their cost (plus the needed filters) is almost unaffordable.

They are also energy hogs. A typical room air cleaner running 24/7 – as it must to be truly effective – uses about 800 kilowatt-hours of electricity per year, or 50 percent more energy than is used by a new refrigerator.

Without naming brands, I’m going to point to a $475 whole-house air cleaner that weighs 38 pounds, and offers 250 cfm on its highest setting. A pack of replacement filters (pre-filter and HEPA filter) cost $150 (most of that for the HEPA unit), with the first needing replacement three times a year, and the second once every five years.

If that were true, it might almost be worth the investment. Unfortunately, it’s seldom true, and most users report changing out the expensive filter at least yearly.


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A room-sized air cleaner (for a 17 ft. x 22 ft. room) costs $169, offers 250 cfm maximum air flow and the main HEPA filter, which costs $90, should be replaced at least yearly, though many users who need air filters report changing it every six months.

These units have reportedly become more reliable in the last few years, but the fans in the two that I owned about five years ago each failed at about 14 months. The five-year limited warranty (material defects only) is also an improvement over the original, but the owner still has to pack it up and ship it back – no small chore – and the noise is a little more than you’d expect for something this pricey. You probably wouldn’t put it in a bedroom, anyway.

What makes these units appealing to allergy sufferers? The HEPA filtration, which according to established standards, must trap 99.97 percent of all airborne contaminants larger than 0.3 microns. Note; HEPA is not a brand name, but a filtration standard, and not the only one in existence. The American Society of Heating Refrigeration and Air Conditioning Engineers, or ASHRAE, has its own rating system, called Minimum Efficiency Reporting Values, or MERV, which ranges from 1 to 16 (16 being the best) and many air filter manufacturers now label their products with a MERV rating.

However, HEPA standards still exceed MERV specifications, which make them at least 50 percent more effective. The problem is cost, and you, the homeowner, can get around that prohibitive cost by making your own air cleaner.

7 Steps to Make Your Own Inexpensive Room Air Cleaner

  1. Start with a good, 20-inch box fan. This will cost between $20 and $35, and give you three air speeds, the highest at 2220 cfm, or about ten times that of an air cleaner.—
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  2. Next, go to your local hardware or home repair store and buy a 20-inch HEPA furnace filter (up to $20) and some aluminum or extruded vinyl U channel, or track – one inch wide and at least a half-inch deep – which you will attach to the back of the fan, along the sides and part of the bottom.—
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  3. If you have a drill, you can use aluminum. If you don’t, choose vinyl and a good vinyl glue. Cut two side pieces (shorter than 20 inches) and one or two bottom pieces, keeping in mind that the cord comes out this area and you can’t easily or safely change that.
  4. To cut the channel, you will need either a good pair of wire cutting pliers or a hacksaw. If using pliers, cut the open ends first, then bend the channel away from the cut to access the center channel. But it isn’t rocket science, and the cuts don’t have to be exact.
  5. You can either lay the filter itself on the back of the fan and mark the edges, allowing 1/8 inch for the channel, or put the channels on the filter and mark the fan with the channels attached. This is the more difficult but more exact way. If using aluminum, sand, buff or tape the cut edges to prevent injury. Sand the cut edges of extruded vinyl as well.
  6. Drill and screw the channels in place, using screws no longer than those holding the fan’s faceplate, or glue the channels in place, leaving room for the cord.
  7. When finished (and once the glue is dry), simply slide the filter into the channels and you have a HEPA filter costing about $40 that will even filter out cigarette and cooking smoke. Equally as important, your fan uses about 30 kilowatt hours per month, costing you less than half as much to run as a room-sized air cleaner.

If you’re less concerned about HEPA filtration for allergies, and simply want to cut down on dust, mold spores and pet dander, you can use less expensive (and more porous) filters, which will keep air flow above 1,500 cfm – as opposed to HEPA filtration, which cuts air flow about in half, leaving you with about 1,100 cfm, or four times that of an “official” air cleaner.

A $7 filter, with a MERV rating of 8, will perform admirably. Buying filters in quantity, as 3- or 6-packs, will also save money.

Homepage photo credit: ka tate