Air Purifier: to Buy or to DIY?

Llbreav on 20/07/2022 - 19:50

I decided to buy an air purifier. My problem is more with dust, pollen, pet hair, and smoke than it is with viral particles.

I recently got my $ returned on the price error $66.66 Renpho air filter with extra filters: https://www.ozbargain.com.au/node/709799

I have been reading various recommendations, and see the Philips units are well-regarded on Ozbargain.
Can currently get the Philips 1000 for $279 at HN

Also the Xiaomi units
Mi 4 for $237 at https://www.ebay.com.au/itm/374117992649
and the smaller Mi 4 Lite for $190 at https://www.ebay.com.au/itm/354120697215

The most aesthetically appealing one I have found is the Briiv which costs around $550AU + postage from the UK
https://www.briiv.co.uk/
It uses the often cited (and often 'debunked') NASA Clean Air Study tech - but is "as powerful as 3,043 medium size houseplants".
I like the fact it is not using environmentally unfriendly HEPA filters

I have also read a number of box-fan DIY purifier projects - e.g. https://cleanaircrew.org/box-fan-filters/
I had a look at MERV-13 filters on Amazon. Not much available locally that I could find, and very expensive
But these 3m Merv-13 filters are is 4 for $68 which seems reasonable (coming from US): https://www.amazon.com.au/Filtrete-Ultimate-Allergen-Reducti…
But I would also want to do some kind of pre-filtration to make the filters last longer - and quickly it starts to get pretty expensive, will probably be noisier than many of the existing models, be larger, uglier, and a pain to move around.

Anybody want to offer advice, or to suggest neglected options?

Home & Garden Air Purifier

Comments

  • morse on 20/07/2022 - 19:57

    I don’t know much about the difference in specs but have noticed these at Kmart
    https://www.kmart.com.au/product/small-tower-air-purifier-42…
    https://www.kmart.com.au/product/large-family-air-purifier-4…
    Low stock but still some in store depending on where you live.
    You could also consider a robot vacuum and regular wet dusting.

  • AustriaBargain on 20/07/2022 - 21:01
    +1

    Unless you're a uni student you should probably get a proper unit, instead of strapping a big filter to a cheap box fan.

    • lbreav on 20/07/2022 - 22:07

      Well, unfortunately a lot of the "proper units" perform significantly worse than a hepa filter stuck on the intake side of a box fan.

      https://www.cbc.ca/news/business/portable-air-purifier-tests…

      You will see that the Dyson which is about $1k AU performed a lot worse than the DIY job.

      From what I found looking up the Ikea units, the Förnuftig is 130m3/hr.

      Kmart lists 320m3/hr for the family unit, but doesn't give a number on the small ($50) one.

  • meowsers on 20/07/2022 - 21:26
    +2

    we bough an inova HEPA system.

    To be honest you buy something once, you get the best thing and you dont worry.

    https://inovaairpurifiers.com.au/collections/commercial-air-…

  • WoodYouLikeSomeCash on 20/07/2022 - 21:31

    The Samsung ones aren’t bad.

  • lbreav on 20/07/2022 - 22:31

    This Philips 2000i is $449 + $100 cashback at the moment, which is $250 off RRP
    https://www.amazon.com.au/Purifier-Allergens-Compatible-AC29…

    Anyone know if it is significantly better than the 1000, which is currently $270 (but ineligible for the cashback)?
    The quoted figures seem like it works for a bigger area, and has a higher cadr, but hard to find a comparative review

    The replacement filters seem very expensive for these.

  • meeowth on 20/07/2022 - 23:03
    +2

    As you have no doubt noticed, DIYing is much for feasible for people in the USA due to the pervasive presence of cheap HEPA furnace filters sold for the extremely common central AC systems they have over there.

    Here, finding cheap HEPA filters that are competitive with the price of replacing the filter on a non-diy unit, (long-term, the most relevant consideration for an air purifier is how much it will cost you per year to replace the filter(s)), can be challenging depending on where in oz you live.

    By the way, you can massively increase the lifespan of some filters by covering them in electrostatic cotton so that dust sticks to the cotton instead of gumming up the HEPA filtering. Here's an example of ones sized to cover Xiaomi filters" https://www.amazon.com.au/Electrostatic-Cotton-Replacement-P…
    Of course the Xiaomi doesn't know about the cotton and will still tell you to replace the filter way before you need to, but they run fine even if they complain on the little screen.

    Now a smart purifier manufacturer will put a separate "carbon" filter in front of the HEPA filter that collects the dust instead. Its fine to just vacuum the dust off this instead of replacing it unless you really need the smell reduction power of fresh carbon.

    • lbreav on 21/07/2022 - 11:54

      Thanks! Do you know if there are any of these cotton covers for a Philips 2000i? I had a look, but the ones advertising Xiaomi + Philips list the Xiaomi products they fit, but not the Philips … The 2000i has an active carbon filter, but it looks like it is on the inside and relatively hard to clean.

      • meeowth on 21/07/2022 - 22:34

        Yeah when the active carbon filter isn't a separate removable filter it can't really be used as a cleanable dust guard.

        The Philips filter seems to be a little shorter than the Xiaomi so the electrostatic cotton probably fits fine, maybe with cutting a little excess off. Xiaomi only makes one size filter for all models so listing all of them is just inflating the listing.

        The cotton is just a flat sheet with some double-sided tape pre-applied to one end so you can wrap it around the tubular Xiaomi/Phillips filter and then secure with the tape.

        For air purifiers that have flat square filters this is obviously not needed, you can just get some generic electrostatic cotton sheets and place them in front of the square filter.

  • MrsJones on 21/07/2022 - 08:30
    +2

    Just plug in your room dimensions etc and use the recommendation from here https://cleanairstars.com/filters/

    The page is run by an Australian doctor who is trying to advocate for air quality.

    • lbreav on 21/07/2022 - 11:37

      Thanks - this is good, and he recommends the DIY option. But the range of models listed is far from complete

      • MrsJones on 22/07/2022 - 15:16

        Yeah it’s only the models that have provided sufficient data or they’ve had time to do testing on.

      • brendan0 on 22/07/2022 - 17:14
        +2

        The CADR numbers on that spreadsheet for the DIY are very very rough. I'm not convinced that at A$90 for the Dimplex box fan and A$140 for the 3M MERV 13 filters, makes economical sense in Australia. Plus you also have to bear the replacement filter costs without the benefit of a pre-filter mesh that is typical of commercial air purifier models.

  • donga100 on 21/07/2022 - 09:11
    +3

    Just buy 3,043 medium size houseplants

  • GreyChris on 21/07/2022 - 09:22

    I have 3Hs at home near the kitchen and at work and love them. The onscreen pollution readouts are really helpful. Replacements are about $30 on kogan and they last a while.

    • Euphemistic on 22/07/2022 - 07:28

      But does it make a noticeable difference to air quality or just make you fell better because the number on the screen is there?

      • GreyChris on 23/07/2022 - 17:19

        The machine does bring the numbers down however opening a window does also bring down the number… Unless there's bushfire smoke outside.

        I do think it's good to know objectively when pollution levels are very high and when to do something about it. With gas cooking it can be subtle and with asthmatics around you don't really want unnecessary respiratory events. I feel as though it has reduced asthmatic events however that may be placebo. There is however a linear relationship between increasing particulate matter in the air and health issues.

        • Euphemistic on 23/07/2022 - 17:33

          Yes, but can you notice it or just get a placebo effect because ‘number’s good today’

          Personally, I guess I’m lucky I only really notice it when you can smell bushfire smoke.

  • samyall on 21/07/2022 - 11:35

    This video compares your different options very well: https://www.youtube.com/watch?v=rDZ9yUdM2wA

    • lbreav on 21/07/2022 - 12:07

      Good video - sponsored by Dreo but objective.

  • lbreav on 21/07/2022 - 12:09

    https://smartairfilters.com/en/blog/comparison-diy-filter-ef…

    This is impressive; again in favour of DIY - their DIY method is ultimate simple, but seems to have the filter on the outflow rather than the inflow (not generally recommended)

    Difficulty with good DIY seems to be finding cheap HEPA filters in Aus that aren't 20x20x1" (apparently you want x3" or 4") - and finding a way to cover with an active charcoal filter so you don't churn through expensive HEPAs for filtering large particles.

  • brendan0 on 22/07/2022 - 17:05
    +1

    I've researched it, its not economical to DIY in Australia https://twitter.com/CleanAirStars/status/1472509090823737344

    Unlike the US, its hard to get a good cheap box fan here. The mistralaire https://twitter.com/DrPieterPeach/status/1488839358488940549 that used to be sold by Bunings was a good deal, but they've discontinued it

    Nowadays I'd just go with the IKEA STARKVIND. I particularly like the one hidden under a table https://www.ikea.com/au/en/p/starkvind-table-with-air-purifi…

    • donga100 on 22/07/2022 - 22:42

      its hard to get a good cheap box fan here.

      How cheap does it need to be? $20 seems to be the standard price for them but finding stock in the middle of winter will be a challenge. Mitre 10, Bunnings, Target, etc.

      • brendan0 on 23/07/2022 - 01:02
        +2

        Needs to be 20inx20in to match dimensions of MERV13 filters, and in addition needs to be able to work when you flip it on its back. Most Australian box fans don't come in that size and have a mercury switch so you can't use them to pump air upwards

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