Pre-Filters in HEPA Air Cleaners

Pre-filters lengthen HEPA filter life


Blueair Replacement Filters

Pre-filters extend the life of your HEPA filter inside an air purifier, and pre-filters are not all made the same. I cannot say more about the importance and need for a good pre-filter. Some pre-filters are like a piece of foam, some are like a piece of abrasive padding and the one put out by IQair in their air cleaners is a totally different design entirely. I was opening up all the HEPA filters in our office recently in order to train a new employee. What I found was very illuminating.

Blueair Air Filters

The Blueair air cleaners have no pre-filter but has three HEPA-type filters. The filters were a year old (I deliberately let them run over the manufacturer’s recommended time span). I could see the larger dust particles on the filters, but I also saw some dust on the inside of the air cleaner unit that needed some wiping with a cloth. The intake vents at the machine’s base were also covered with visible dust and needed wiping from the outside. Another little point about Blueair that made me a trifle uncomfortable.

QuietPure Air Filters

I only recently became aware of the QuietPure Home, have their pre-filter incorporated into the filter itself, which makes keeping current with your regular filter really simple. QuietPure has one of the larger filters and is shaped like a cylinder, but that plays an important role in it’s design. The QuietPure Home draws air from the bottom to top. It is also one of the easier filters to replace, all you need to do is gently place the QuietPure on it’s side and unscrewing the filter gate at the bottom of the unit. The filter sits on top of the filter gate panel, so you should probably have a trash bag handy, so dust does not get everywhere. We’ve found them to be reliable and run quietly.

Austin Air Filters

Austin Air Pre-filter & Filters

Next came the Austin Air Healthmate air cleaners. The pre-filter is hidden behind the metal grill and should be vacuumed from the outside. Getting inside a Austin Air is a real production, so I skipped that except for giving the unit a cursory “sniff test”, the manufacturer’s recommended way to figure out whether the filter is shot is to see whether the air smells bad. I wasn’t clear whether it was on its last legs or not so I continue to stare at it balefully, resenting that it does not tell me when to change the filter. Actually, in the Austin manual (which they do not ship with their machines for some reason unbeknownst to me), it tells you to change the pre-filter or wash it in the bath tub every two years. I ought to take courage and do it, but like many people I think the whole operation is a pain in the “whatsit”!

IQAir Air Filters

Then came the IQAir air cleaners – my favorite although I should mention air

IQAir Replacement Filters

cleaners are a good second. We opened up the IQAir easily enough. It was not as simple as the Blueair to open up, but at least no screwdrivers. Then I inspected the state of the pre-filter, which IQAir claim takes out 90% of the particles coming into the air cleaner unit. After 5 months, the pre-filter resembled the inside of a vacuum cleaner bag – there was so much dust. Guess it is doing its job. No wonder the particle counter shows clean air around that air cleaner. I did check with the manufacturer as to whether I could vacuum the pre-filter. I was told firmly to keep my vacuum away from the filter, not a good idea since I could damage it. I also checked the life of the filters at the same time and got a read out – still 5 months left on the pre-filter.

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