[HN Gopher] Reverse engineering Xiaomi air purifier NFC stickers
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Reverse engineering Xiaomi air purifier NFC stickers
Author : thunderbong
Score : 166 points
Date : 2022-05-28 14:00 UTC (8 hours ago)
(HTM) web link (www.flamingo-tech.nl)
(TXT) w3m dump (www.flamingo-tech.nl)
| occz wrote:
| Good stuff. The author of the post has also previously made a
| defeat device that can fairly simply be installed in your
| purifier, which simply reports the filter to always be at 100%.
| Useful if you're in a place where the filter will last
| significantly longer than what Xiaomi thinks. I bought one and it
| works great, I can definitely recommend it.
| KennyBlanken wrote:
| Or just buy a unit from one of the companies that doesn't
| engage in DRM nonsense.
|
| Coway and Winex both do not do this and make top-rated units.
| causality0 wrote:
| Interesting. The concept seems obvious but this is the first I've
| heard of air purifiers using printer-cartridge style artificial
| scarcity.
| BasilPH wrote:
| I've built dynomight's DIY filter[^1], and I love it. No DRM
| issues either.
|
| [^1]: https://dynomight.net/better-DIY-air-purifier.html
| Someone1234 wrote:
| Very cool. Anyone seen a mod that adds activated carbon? A lot
| of DIY filters are very cost-effective, but the lack of
| activated carbon is a big downside compared to commercial
| solutions.
|
| There's really only two air cleaning technologies that are
| worthwhile right now:
|
| - HEPA filters (remove PM 2.5 particulate and above).
|
| - Activated carbon (neutralizes harmful gases).
|
| The only other thing that may be worthwhile is a pre-filter,
| but that is mostly a cost saving measure rather than actually
| improving air filtration.
|
| Unfortunately commercial filters are full of gimmicks that
| don't work or may even be harmful due to Ozone generation (e.g.
| Ionizers, UV lights, et al.).
| papercrane wrote:
| You could buy an activated charcoal filter built to attach to
| the same inline fan booster from most garden stores that
| carry indoor growing equipment. They're popular with people
| growing cannabis indoors to remove the smell from their grow
| area.
|
| Something like this:
|
| https://www.amazon.com/dp/B07GSKFBL8/
| joshvm wrote:
| Perhaps a stupid question. Why go to the trouble of bolting
| together four filters, instead of attaching the duct fan to a
| cylindrical HEPA filter? Then you just need two plates: one to
| adapt the duct inlet and one to seal the base of the filter.
|
| I think, as with many DIY projects, one must look to the pot
| growing community. They solved the problem of "how do I not
| stink out my apartment" a long time ago - duct fans and
| HEPA/carbon filters are the mainstay of grow rooms.
| bsder wrote:
| Link? I'm interested.
|
| However, I suspect availability plays into it. Almost anyone
| can pick up a couple of rectangular HEPA filters and a box
| fan from the local hardware or big box store.
|
| I've never seen a cylidrical HEPA filter. So, I probably need
| to order that from an industrial supplier.
|
| And, aren't duct fans kind of noisy? Do they make quiet ones?
|
| In addition, this fan/filter seems even easier:
| https://smartairfilters.com/en/blog/cannon/
| joshvm wrote:
| The duct fan + filter combo is how lots of cylindrical
| consumer units work (e.g. Levoit, Philips, etc). They just
| use crappy fans which don't really pull any air through, or
| they're very expensive for what they are. In terms of
| availability, I think the current popularity helped,
| otherwise you could also look at the auto market, lots of
| cylindrical filters there and they'd be fine for pulling
| out stuff like pollen, though you might want a carbon
| filter as well.
|
| I have no idea what's required for HEPA certification, but
| lots claim to be:
|
| https://www.amazon.com/LEVOIT-Core-Replacement-High-
| Efficien...
|
| It has an outer dust mesh, the HEPA filter and a carbon
| insert. They're all the same though, I think you could use
| any manufacturer's filter. Longevity isn't really an issue
| if a supplier goes bust, just re-make the adapter ring.
| Pretty much all you need and you don't need to worry about
| sealing the corners.
|
| According to OP's link, they use a duct fan booster which
| is a lot quieter than a box fan (at least the claim is it
| can go down to 16 dB).
|
| Though a question is does a can-shape system work better?
| Or would you get the same effect if you used a single flat
| filter with the same "unrolled" area? I have no idea, and
| there's so much uncertainty involved with DIY testing.
| jrochkind1 wrote:
| Hm, I feel like cylindrical HEPA filters are common for
| shop vacs and widely available? Searching "HEPA filter shop
| vac" on home depot gets what looks like plenty; or are
| these not what would work for that kind of design, maybe
| we're talking about different things? They are
| "cylindrical" by being pleated.
| kortex wrote:
| Cost and availability. Cylinder filters tend to be way more
| expensive ($30-50 per, I've seen true HEPA cylinder ones "for
| allergy sufferers" aka medical space, >$130) than rectangular
| (a few bucks). Rectangular also comes in a wider variety of
| form factors than cylinders, with more different filter
| styles (eg different thickness, with carbon, high flow, true
| HEPA/MERV >13).
| someotherperson wrote:
| I go back to that page often. I might finally buy the parts
| tonight and actually make it instead of just thinking about it
| :)
| random3 wrote:
| Can someone explain what's the result of filter utilization /
| capacity. Is it efficiency? Does it start spilling out particles?
|
| I feel like a 100% used filter will still do a pretty good job,
| so unclear how much of the utilization % has commercial
| reasoning?
| sschueller wrote:
| My assumption is that a "Full" filter has a reduced airflow
| which means the fan pulling air in has to work harder. If it is
| spected very tight then I could see it failing more quickly.
| Waterluvian wrote:
| My intuition is that the more "full" it is, the less air will
| flow through it, meaning it just doesn't do as much.
|
| Not to suggest that what the manufacture decides "100%" is is
| actually that.
| oh_sigh wrote:
| That's exactly right for HEPA filters, not sure about other
| types of filters though.
| thaeli wrote:
| This applies for any media filter. VFD drive on the motor
| can keep airflow constant and increase energy usage
| instead, but for most fans the increase in static pressure
| means less air volume. Heavily loaded filters can also have
| more air bypassing the filter, which may or may not be
| significant depending on the application. For this kind of
| air filter bypass just subtracts from the airflow through
| the filter media.
| KennyBlanken wrote:
| Efficiency in terms of airflow goes down, and static pressure
| difference goes up - but the filters trap more of the particles
| going through them. Changing filters on furnaces and AC units
| is really important, since lack of airflow hurts efficiency.
|
| Wirecutter (which is usually trash) confirmed this in testing;
| versions of units that had been running for months or longer
| (ie one they bought a year ago and used in someone's home, vs a
| new unit bought new with little run time) tended to perform
| better in terms of how many particles they completely removed.
|
| The unit starts using more electricity to do the same work, has
| to run at higher fan speeds, etc. So it's a tradeoff between
| that and the cost and waste generated by buying more filters.
| ehPReth wrote:
| curious - why is Wirecutter trash? I've been sorta feeling
| iffy about them for no real reasons but they seem highly
| recommended
| inferiorhuman wrote:
| With air purifiers at least Wirecutter completely ignores
| known problems in order to collect sweet, sweet referral
| fees. Comments about the high levels of VOCs in some
| brands' filters, fans exploding, etc. all get/got ignored.
|
| In my case I bought a couple Coway air purifiers only to
| find that Coway doesn't honor their warranty. I hit all the
| common complaints from the comments section - comments
| Wirecutter staff refuse to acknowledge.
| lostlogin wrote:
| I was reading their list of coffee grinder recommendations.
| Some they recommend I got rid of years ago as they aren't
| very good. It may be the case that they had a price
| ceiling, as the article mentions how costly grinders are,
| but it's certainly dropped my opinion of Wirecutter.
| rhexs wrote:
| They almost always conveniently only recommend products
| that allow for referral fees.
| aardvarkr wrote:
| The product manufacturers don't pay referral fees, it's
| the retailer. So your entire argument against them is
| you're mad they make money by linking to Amazon or
| target?
| wincy wrote:
| I'd definitely prefer something like Consumer Reports who
| has the budget to expose scams like Molekule who claim to
| invent some magical new type of air purification.
| inferiorhuman wrote:
| > So your entire argument against them is you're mad they
| make money by linking to Amazon or target?
|
| That's not my entire problem with them, but it's a
| problem. Because they're reliant on referral fees their
| motivation is purely to get you to buy random crap
| whether or not it's any good. So long as their reputation
| holds up that's good, but once they start promoting crap
| there's going to be a long tail of folks who think "oh
| it's on wirecutter, it must be good".
|
| Take a look at their reviews. It's not that they promote
| stuff that they might get a kickback on, Wirecutter
| _only_ promotes stuff they can generate a referral link
| to.
| [deleted]
| eli wrote:
| so pretty much anything sold by a major retailer?
| SemAntics0 wrote:
| Years ago, they really drilled into the performance of the
| various products they compared and frequently the winner
| was a specialist product from a brand you had never heard
| of, but it really was the best on the market. Wirecutter
| articles did good testing with defined rationale that might
| not be up to laboratory standards, but it was enough to
| clearly identify which products were offering the best
| performance. When they labeled a product "The Best X", you
| could be fairly confident that it was going to outperform
| almost everything else on the market. They tested
| everything from the highest range products to the garbage
| chinesium specials and if you read the entire article, you
| could see where some products might outperform in certain
| areas, but under perform in others, letting you make an
| informed decision that wasn't simply picking the "Winner".
| Effort had clearly been put into discovering a full range
| of products instead of simply comparing the amazon options.
| Any product that was disqualified from comparison had a
| clear and reasonable rationale.
|
| Starting around 2018 the quality of testing plummeted into
| clickbait territory. Many articles appeared to justify
| their choices entirely based on reading amazon reviews
| without actually putting hands on the product, a theory
| reinforced by waves of comments appearing that despite a
| wirecutter recommendation, the product was absolute junk.
| My personal "Wirecutter is a lost cause" moment was when I
| was looking for a new comforter and the writer had simply
| disqualified every single option that was polyester based
| because "I don't like how polyester feels." That's not good
| testing. That's opinion. If I wanted subjective opinions on
| products I wouldn't be at Wirecutter.
|
| For an contemporary example, pull up their "The Best Drill"
| article. The reviews highlight things you could discover
| from holding the drill and looking at it. The testing is a
| single test performed by a single person with no edge cases
| or alternative uses considered. If ergonomics are such a
| critical consideration that it gets entries shot down,
| shouldn't you have multiple people testing to see how
| different models perform in different people's hands?
| Furthermore, the only products tested are mid-range
| household drills available from big box stores. Nothing
| from the professional brands like Festool or Hilti or some
| brand I've never heard of. No explanation why I shouldn't
| just buy a Harbor Freight special for half the price. No
| explanation why any other consumer-grade brands weren't
| included. The articles don't provide "The best drill",
| they're providing "The best consumer-grade drill for light
| duty work", and this attitude has spread to every corner of
| the site. You can't go to wirecutter and find a specialist
| tool that outperforms the commonly available options any
| more, because they're not even including it in testing.
| diziet wrote:
| The Best Drill article doesn't even mention impact
| drivers, which are going to be tremendously easier on the
| wrist/hand for screwing in screws. An explanation for the
| lay audience would help. Nor are questions such as: "How
| much torque is there? What is the torque curve? How much
| torque do you need? Do you need a hammer drill? What is
| the noise like?" addressed.
|
| I do think more specialty gear is hard to cover, as for
| example the the impact driver here:
| https://www.youtube.com/watch?v=l_pCeGmQU8w or AvE's
| youtube coverage of tools goes beyond that. Project Farm
| tends to have better coverage of general equipment with
| pretty good objective tests:
| https://www.youtube.com/channel/UC2rzsm1Qi6N1X-wuOg_p0Ng
| but even he can't cover all the brands/models: He covered
| Festool but not Hilti's SF 2H-A Hammer, for example.
|
| Techgearlab has pretty unbiased coverage, and they also
| have an small incentive to cover products that have
| affiliate programs -- however, for example their parent
| rock climbing site Crash Pad Coverage:
| https://www.outdoorgearlab.com/topics/climbing/best-
| boulderi... includes Organic pads which have no affiliate
| program.
| 5e92cb50239222b wrote:
| I live in an very polluted area (average PM2.5 level in winter
| around 300 ug/m3) and have been running the same filter non-
| stop in a cheapest Xiaomi purifier for 1.5 years. It's almost
| black, but works fine, as confirmed by DIY PM sensors. I think
| it puts more strain on the motor, but I don't see any
| difference in efficiency.
| jrockway wrote:
| The big problem I see with DRM on air filters is that air filters
| don't do anything complicated. Remove the electronics module and
| connect the fan directly to power. Done. They should have done
| that in the factory and pocketed the profit from not buying
| electronics and NRE.
|
| (This is less possible on things like printers, which have to
| synthesize somewhat complicated motion, carefully release ink at
| the right time, etc.)
| rbrtdrmpc- wrote:
| This is nice! And the timing is perfect for my purifier to
| complain about the second filter that I've so far
| iSloth wrote:
| I've never experienced an air purifier, what's the general
| consensus?
|
| Do they make a difference? Perhaps a placebo? A must have?
|
| Genuinely interested if I'm missing out - For what it's worth I
| do live right on a main road in the UK, so I expect there is some
| level of pollution in the air.
| legulere wrote:
| The soot they filter out of the air is very visible when you
| change the filters (they turn from shining white to grey). Air
| pollution is one of the world's leading risk factors for death
| https://ourworldindata.org/air-pollution#air-pollution-is-on...
| . Though that varies a lot from country to country, it is a
| problem you can strongly reduce with throwing a tiny bit of
| money on it.
| gruez wrote:
| If the filter is only turning Greg it sounds like what you're
| seeing is dust rather than soot. I have a pm2.5 meter and
| over the winter/spring the reading is almost always 0 or low
| single digits, and my filters still turn grey
| DragonStrength wrote:
| The biggest effect is in homes without any sort of central air
| system, which would usually include various levels of filters
| up to HEPA and UV systems at this point. During the worst of
| fire season in the Bay Area though, a single Coway HEPA filter,
| basically a box fan with a HEPA filter strapped to it, kept my
| apartment in the "safe" range for AQI. Just stepping out my apt
| front door into the hallway I'd be hit with the heavy stench of
| smoke.
|
| Truly remarkable how well they work, but whether you need one
| or not depends on whether you have allergens/pollution as an
| issue in your home. You can purchase an air quality monitor (I
| have a Temtop M10) or check online measurements of AQI, pollen,
| etc. for your area. If you have an issue, they work, but not
| everyone has an issue.
| techwiz137 wrote:
| Okay so I bought a cheap-ish Air Purifier, now because the
| brand is...I think it's Chinese(Rohnsonn), I can't determine
| if it really does anything, if these filters do anything at
| all to improve my air quality and if the UV light is even
| strong enough to kill germs. Is there a way to verify it's
| effectiveness?
| DragonStrength wrote:
| I'd look at what the purifier claims to eliminate and find
| a quality monitor that will give you a reading. Most are
| portable, so you can compare to outdoor values directly.
| You're going to need some baseline to compare to though. If
| you have an AQI in the safe range already in your home,
| you'd have to contrive some actual experiments or find
| someone who already has.
|
| I'll say I'm pretty distrustful of anything but filters
| personally. My mom purchased a purifier at one point which
| claimed to use UV light to purify but had no fan to
| actually pull air through the light, so obviously, it
| wasn't doing anything.
| jaqalopes wrote:
| Ancedotally they work 100%. Not only do they remove noticeable
| odors, they suck up tons of allergenic dust and invisible
| particulates that can mess with your breathing (if you have a
| sensitive respiratory system).
|
| Non-anecdotally, I've heard it claimed that indoor air
| pollution is the #1 factor in reducing the lifespans of
| otherwise healthy people. No idea if this is the case or what
| the evidence is, but I don't find it hard to believe.
| Rastonbury wrote:
| In developing countries they have poor stoves at home which
| give of smoke/CO which is harmful aka indoor air pollution. A
| good easy way to prevents deaths/harm from these is to
| provide them with quality stoves. So depending on where you
| heard it, air pollution could mean these stoves which typical
| don't exist in the developed world
| Rebelgecko wrote:
| Even in developed countries, I think most homes still have
| gas stoves which are bad for indoor air quality.
| legulere wrote:
| Frying things even on induction still easily drives
| particulate matter pollution to levels of bad days in
| China/India.
| azuredragon wrote:
| They also double as a mosquito trap. I used to suffer
| persistent mosquito annoyance at night, but, since I got an air
| filter, the problem is gone. I often clean out dead mosquitos
| from the air filter
| hammock wrote:
| I was so skeptical. Living in SF in 2018(?) during the
| wildfires, my apartment was drafty and I'd come home from work
| to a hazy indoor environment. I'd wake up with a sore throat
| and that's what got me to take action (can't sleep with an n95
| on)
|
| I got the cheapest air purifier from Amazon and just put it on
| my bedside table. After one night my sore throat was gone.
|
| As simple as these machines are, they do work.
| CoastalCoder wrote:
| I can see how an air purifier makes sense in that 2018
| scenario.
|
| I guessing that the benefits are less certain in more typical
| cases.
| AlotOfReading wrote:
| Higher air pollution, especially during childhood, is also
| strongly linked to the development of asthma and other
| respiratory issues later in life. Pretty much everyone
| should at least be aware of their home air quality.
| hammock wrote:
| The benefits, yes. Those would be dependent on the local
| environment and if it's causing you specific suffering. But
| that experience sold me on the functionality at least.
| imajoredinecon wrote:
| > that 2018 scenario
|
| It's a little hard to believe if you haven't lived there
| recently, but basically the entire US west coast now has an
| annual fire season where you can expect at least several
| days of air quality in the "unhealthy" to "hazardous"
| range. AC (which does ~the same thing for air quality as a
| purifier) or a purifier is pretty much mandatory.
| samstave wrote:
| When the fires were raging, I was looking at all the
| areas air quality from purple air monitors and some areas
| near folsom California were at ~700
|
| And healthy is something like <100
| haunter wrote:
| My parents live in a very old house (~1700s) and it reduced the
| dust significantly. Not perfect but maybe it's on the model
| too. Like it's not an $1000 one which would probably work much
| better
| input_sh wrote:
| They're pretty much all the same, just a fan in front of a
| HEPA filter. If you can get a square fan and tape a HEPA
| filter in front of it you'd get pretty much the same result
| as many modern air purifiers.
|
| You're paying for convenience and some bells and whistles
| (like a mobile app and an air quality reader), but the
| underlying technology behind it is pretty bare-bones, heavily
| tested, and heavily used in industrial applications.
| arinlen wrote:
| > _Do they make a difference? Perhaps a placebo? A must have?_
|
| It really depends on where you're coming from.
|
| I have one of those air purifiers from Ikea (Fornuftig). It's
| cheap but not the cheapest. On any high dust/polen
| concentration level day, a minute or so with the device turned
| on at full blast is enough to make any problem go away in that
| particular room.
| dxhdr wrote:
| > Do they make a difference? Perhaps a placebo? A must have?
|
| Purchase an air quality monitor, something like the Dylos
| DC1100. Then run a HEPA filter in a closed room for 30 minutes.
| It will remove almost all particulates! They work extremely
| well. Whether it "makes a difference" for your health is less
| clear.
| criddell wrote:
| Are the lower priced options on Amazon junk compared to the
| DC1100? I'd like to get a monitor, but I know I'll probably
| only use it 10 times. The Dylos would end up being about $25
| / reading...
| dxhdr wrote:
| Good question, I bought a Dylos back in 2015 and can't
| remember how the other options stacked up when I researched
| it. I've been happy with the purchase and would recommend
| it if you're interested in watching air quality. It has a
| convenient "monitor mode" where it will re-sample the air
| every hour so it's not constantly running. It's neat to see
| how the air quality in a room changes based on having the
| windows open or shut, after cooking, just being in the
| room, etc.
|
| I'd expect there are smaller / sleeker / more advanced
| monitors out now though. Generally speaking I think you
| want a laser detector instead of the cheaper infrared
| detectors.
| criddell wrote:
| I found this link with test results:
|
| https://www.aqmd.gov/aq-spec/evaluations/summary-pm
| trompetenaccoun wrote:
| If you don't understand the purpose, it means you don't need it
| - as so often. The reason they exist is that in some parts of
| the world the air is so bad it literally has significant
| negative health effects just breathing it. That's why people
| use them, and for what it's worth as far as I understand the
| quality ones do work, in the sense that you can use an air
| quality meter and detect a noticeable improvement in air
| quality. They have filters that you need to change regularly.
|
| -Edit- Since so many people are raving about them and
| recommending you buying an air purifier I want to add this: If
| you live in a place where the air is truly that bad, my main
| recommendation would be to move. I have personal experience
| with this, it's not worth it living like that. You may filter
| the air in your home but then whenever you go outside you're at
| risk, if you do sports even more so. Some people wear surgical
| or cheap cloth masks but these don't actually work.
|
| Don't listen to people who tell you that you can "see"
| pollution of "feel" the difference. I've lived in some of the
| most polluted cities in the world and the truth is in most
| cases for regular healthy people they don't notice anything for
| years, even at pollution levels far beyond the imagination of
| folks in Western countries. Most of this is their imagination
| or placebo like you suspect. For example I've had people
| complain to me that the air is "so bad" in a place that's
| naturally foggy and where visibility is often low, but had good
| air quality. Others were happy about the lovely "clean" skys in
| a city that gets lots of sunshine but was actually horribly
| polluted. Also sure, smoke from wildfires is visible (and short
| lived) but a lot of the pollution from industrial sources
| isn't. It's a slow and stealthy killer.
| radicality wrote:
| I recently got a Medify Air MA 125 after a lot of research. Can
| recommend the brand.
|
| And yes it definitely makes a difference. Sometimes when I open
| my windows to get some "fresh" air and remove the co2 from my
| room, the ppm momentarily goes up. Also very useful for cooking
| since I don't have a great vent. Ocassionaly when frying
| something ppm goes over 200 but it quickly drops down with the
| air filter.
| KennyBlanken wrote:
| If you have central air heating/AC and a vacuum cleaner that
| has a hepa bag, you likely don't need one; just buy filters
| that aren't the blue spiderweb kind and vacuum regularly.
| dzhiurgis wrote:
| HRV frequently has filters too
| ms4720 wrote:
| Depends on a few things:
|
| 1. what that particular filter filters out: ppm, mold,
| chemicals 2. What is in the air being filtered 3. How sensitive
| you are to the things in your air 4. How often the rooms air
| gets filtered through the filter 5. How effective the filter is
|
| I worked in Beijing for a while and going somewhere with
| filtered air literally felt like a weight was removed some
| days.
| Joeri wrote:
| We live in the city and always are struggling with allergies.
| The whole family is always coughing or sneezing. We bought a
| xiaomi air purifier like in the article last week, started
| using it in the bedrooms for a few hours in the evening, and
| the allergies cleared up overnight. The particulate sensor is
| mostly useless, a known problem with the xiaomi models, but
| running it at a fixed setting seems to clean the air quite
| effectively.
| andor wrote:
| The particulate sensor on my Xiaomi air purifier correlates
| really well with the numbers from my city's air quality
| network.
|
| What doesn't work well for me is the auto mode, it barely
| does anything at less than 50ug/m^3, way too high even for
| the mediocre air in my area. So instead I use automation in
| their app to let it run at full speed for 30 or 60 minutes.
| 5e92cb50239222b wrote:
| They use Chinese air quality standards, which are very high
| relative to most other countries for (probably) obvious
| reasons.
|
| https://en.wikipedia.org/wiki/Ambient_air_quality_criteria
| MengerSponge wrote:
| If you live on a main road, there's likely a lot of pollution
| in the air. How much is actually in your home will depend on a
| lot of complicated things (prevailing winds, home construction,
| etc), so it's best and easiest to just measure.
|
| HN's own https://news.ycombinator.com/user?id=ahaucnx has a
| company with a DIY version:
| https://news.ycombinator.com/item?id=27124671
|
| I got a Dylos before I learned about AirGradient, and I really
| like it too. Depending on your budget and tech savviness, it's
| a great option too.
|
| One important note: these detectors don't do chemistry, and not
| _everything_ that causes a spike of PM is actually a problem.
| Showering, for example, will cause a spike for hours, but those
| salts are probably fine. Running the oven will also cause a
| spike, and those particles probably _aren 't_ fine.
| [deleted]
| throwaway290 wrote:
| There is no level of pm2.5 that is considered safe to breathe,
| and it is easy to find out levels in your area so make your own
| call based on that.
|
| It will be a placebo if your home cannot be isolated from
| outside air or if you don't make an effort to keep windows
| closed when air is bad.
|
| Also, many expensive purifiers are overpriced junk compared to
| even simple DIY solutions like those found on particlecounting
| Tumblr and similar. Ideally the first thing to do is get some
| reputable air quality monitors.
| Mister_Snuggles wrote:
| One of my cats, who's since passed away, was asthmatic. Air
| purifiers throughout the house and a motion activated box fan
| plus furnace filter near the litterboxes resulted in an
| immediate and noticeable improvement in his quality of life.
| I've noticed a similar improvement in my own health.
|
| I've since ended up with a variety of air cleaners:
|
| * IKEA FORNUFTIG[0] is a small and relatively quiet unit. It
| can be wall-mounted, so it can take up virtually no space. The
| unit is reasonably priced. Filters are cheap.
|
| * IKEA STARKVIND[1] is a much larger unit (also available in
| end table form[2] to save space), but also relatively quiet on
| the lower speeds. It's an interesting unit - integrates into
| Home Assistant (the unit speaks Zigbee), and has a PM2.5 air
| quality sensor. This unit is a lot more expensive than the
| FORNUFTIG, but the filters are reasonably priced.
|
| * The box fan plus single furnace filter is incredibly noisy,
| but really good at dealing with cat litter dust. There is a
| huge range of price/quality when it comes to filters[, I just
| use the cheaper ones since I'm focusing on large dust
| particles.
|
| * I have a couple of units that use Bionaire aer1 filters[3].
| The units I have are quiet and reasonably sized, though they
| get louder as the filter fills up. The filters are expensive,
| and one of the units takes two of them which doesn't help
| matters. There is a variety of filters available.
|
| There's a huge spectrum of tradeoffs between noise, size of the
| unit, filtration effectiveness, replacement filter cost, and
| extra features. I'm not convinced I've found the sweet spot
| yet.
|
| [0] https://www.ikea.com/ca/en/p/foernuftig-air-purifier-
| white-5...
|
| [1] https://www.ikea.com/ca/en/p/starkvind-air-purifier-
| black-40...
|
| [2] https://www.ikea.com/ca/en/p/starkvind-table-with-air-
| purifi...
|
| [3] https://www.bionairecanada.com/en_CA/service-and-
| support/aer...
| phphphphp wrote:
| I (in London) bought one recently (a COWAY Airmega) to try and
| improve the air quality in my apartment, specifically, the dust
| which has been reeking havoc on my breathing because of
| allergies.
|
| There is a noticeable improvement but it has not solved the
| problem by any stretch: so while I don't regret the purchase,
| and will keep using it, I am not how sure I'd recommend them
| for the someone without breathing difficulties / allergies etc.
| teaearlgraycold wrote:
| I got the same one and it's amazing for California when the
| air is smokey.
| herbst wrote:
| If you smoke indoors it's a must have I would say. It's a
| difference between day and night.
| fragmede wrote:
| PM2.5 particles are considered harmful, ingest at your own
| peril. Some air filters will also include an air monitoring
| device, so you can just for yourself how many of those
| particles are present (partially burnt food is an extremely
| common source of these).
| stavros wrote:
| Is there something that works well for cat hair? I can't stand it
| everywhere, but I don't know if these filters will catch them. I
| tried to build a box fan filter, but it moved basically no air :(
| Aerialoo wrote:
| Use a bigger fan
| romseb wrote:
| > This will significantly decrease the waste footprint from a
| whole filter.. to just a sticker
|
| I don't think I understand which problem this solves. I can turn
| on my Xiaomi Air Purifier with or without a filter. It's just a
| fan. Is this about a new version that does not work with an old
| filter?
| GekkePrutser wrote:
| Mine too, I have the 2S.
|
| However I have read that the new air purifiers (from the 3
| onwards) switch off after a couple of hours when they don't see
| a filter sticker, or a used-up one.
| pawelos wrote:
| I have Air Purifier 3H, and with an old filter it displays big
| red "0%" most of the time, instead of showing PM2.5 level.
| Which is annoying.
|
| And the filter works effectively a few times longer than what
| is displayed (at least according to the PM2.5 sensors on the
| same device).
| throwaway4good wrote:
| Nice hack. But my xiaomi air purifier works just fine with a non-
| xiaomi filter - only thing it will do extra is show a warning at
| power on.
| GekkePrutser wrote:
| True for the older models but the new ones switch off after a
| certain time
| throwaway4good wrote:
| Mine is a 3H.
| GekkePrutser wrote:
| Oh ok, I heard some of them switch off for sure (after a
| few hours). I read this on an online forum discussing
| integration with Home Assistant, some users got around it
| by just setting an automation in Home Assistant to switch
| it back on again :) Which is what I would have done if my
| 3S had had the same problem. But it doesn't.
|
| Strange that some models are affected but others not.
| throwaway4good wrote:
| Maybe it is because I am in the EU? This stuff is
| obviously in software and all my xiaomi gadgets get ota
| updates regularly.
| JohnJamesRambo wrote:
| The air purifier people must have met some printer ink people
| at a conference.
| VoidWhisperer wrote:
| I think my question with this would be:
|
| How accurate is the filter durability that the normal filter <->
| air purifier tracks? If it tracks reasonably well (which, without
| more info, I have my doubts for the same reason printer ink
| cartridge capacity tracking is bad), wouldn't using these
| stickers kind of defeat the purpose of using the filter in the
| air purifier, since these kinds of filters do have finite
| durability and after that it isn't purifying the air as well as
| it could be.
| GekkePrutser wrote:
| I have one and it tracks very poorly. It tracks only the usage
| time regardless of how fast the fan is running.
|
| When on auto, it is mostly spinning at idle, hardly sucking air
| through the filter, and as such it's hardly contaminating the
| air filter (in fact the airflow is so low I stopped using auto
| mode at all, there is just no point).
|
| It also doesn't take into account how contaiminated the ambient
| air is (even though it has an air quality sensor on the one I
| have).
|
| I run mine at about 40% so I use the filters about 2-3
| lifetimes :) Even that is a pessimistic approach IMO because
| the air here is very clean. I mainly have it because of
| hayfever (pollen allergy).
| chmars wrote:
| In automatic mode, different ppm level should result in
| higher fan speeds. That is at least the case with my filters.
| Cooking for example can be a trigger.
|
| You are of course right that automatic mode does not do much.
| At the same time, higher fan speeds are noticeable (and
| annoying).
| GekkePrutser wrote:
| For my environment it never ramps up in that mode at all.
| Ambient levels are never higher than 10ppm or so.
|
| I know the sensor works because once there was a small bin
| fire outside. There was no visible smoke indoors, I only
| noticed a slight smell. But the purifier immediately ramped
| up and showed over 200ppm.. So it does work.
|
| I'm surprised it's so low as I live at the 2nd floor on a
| fairly busy street with many diesel buses passing.
| chmars wrote:
| The filter durability is time-based in my experience:
|
| I set up several air purifiers at the same time in December
| 2021 but used them in different areas, i.e., with different
| filter loads. The air purifiers ran 24/7 and mostly in
| automatic mode, except for some hours after known possible
| coronavirus exposures.
|
| Official end of filter life was reached after about five months
| and for all filters on the same day. The air purifiers are
| still running tough, that's a plus!
|
| Xiaomi recommends to replace filters every 6 to 12 months. The
| recommendation, however, is based on the use in polluted Asian
| cities, I guess. We have rather clean air here. I therefore
| assume that it is safe to use the filter for an additional few
| months.
| Danieru wrote:
| HEPA filters get more effective overtime in exchange for more
| restricted airflow. Thus the failure mode is "air is not
| flowing" and not "air is not getting cleaned".
|
| At home I use 3 air filters in various rooms. These are
| standard/mid-range Japanese Sharp filters. Japanese because
| we live in Japan, not because Japanese HEPA filters are
| special. The filters themselves can be bought for about 30$
| online. When the filters get near end of life I've had
| success by switching to a higher fan speed. This is not
| magic, at some point even on the highest setting airflow
| starts to match the old medium speed. The high speed mode
| consumes about 4x the electricity of medium speed.
|
| The net result is there exists an intersection point where
| continuing to use a filter costs more money than replacing.
| For us in Japan with expensive electricity this point exists
| sometime after the airflow has diminished but the filter is
| viable on high speed. In cheap electricity countries the
| filter might become unusable before electricity becomes a
| significant cost.
| 5e92cb50239222b wrote:
| > because we live in Japan
|
| May I ask why you're using them at all? Every time I look
| at Japanese cities they seem to have PM2.5 levels in a
| second-digit microgram range. A bad day seems to be
| something like 15 ug.
| bjoli wrote:
| Poor ventilation and a stir fry on medium-high heat will
| bring you above harmful levels for several hours in my
| experience.
|
| Candles, cleaning, frying. All very good ways to increase
| air pollution in your home that nobody speaks about.
| deno wrote:
| In my unit it's just 365 days countdown.
|
| OTOH a lot of the Xiaomi purifiers have built-in air quality
| monitor so really you can just ignore the useless filter health
| value and figure out if the filter is working for yourself,
| based on how it performs.
| userbinator wrote:
| If they wanted to really track the filter life, they would use
| a static pressure sensor like a lot of HVAC installations have.
| It's clear what the companies doing this DRM shit are
| prioritising, and it's not accuracy.
| qgin wrote:
| This is maybe the wrong place to post this, but with fire season
| approaching, a pretty decent high-volume air purifier can be made
| using filters, tape, and a box fan:
|
| https://www.texairfilters.com/a-variation-on-the-box-fan-wit...
| oppositelock wrote:
| I used box fan filter setup to get through a couple of CA
| wildfire seasons, but they're loud and take lots of room. I
| used 4" filters in a triangle with the fan as the base. This
| setup is far more effective than a single filter because it
| makes the fan work better with some air space behind it.
|
| These days, I have a BlueAir 211 in each room. It's the same
| idea, just professionally made, it's not an eyesore, and it's
| quiet. Going by my AQI meter, they're also more effective.
| [deleted]
| [deleted]
| muxneo wrote:
| Absolutely brilliant. Saved 100 to 300 bucks right there.
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