DIY PM2.5 Air Purifier using the fan you already own

[Jimbo1964]

There are also nano-silver filters available here in LoS http://www.iaq-technologies.com/iaq-virus-keeper_filters-pm2-5/

[lsemprini]

53 minutes ago, Trujillo said:

I imagine that this would be more efficient if the fan it pulling the air through the filter, rather than trying to push it through, so putting the filter on the back of the fan seems better to me. 

 

That's what we thought too, but it turns out the efficiency is almost the same (assuming the length of the tube in front and back is same), and more importantly, putting the filter on the back creates a fatal overheating problem.  For all the details, see:

 

https://slice-of-thai.com/air/#p2

 

and to read from someone from Smart Air Filters who studied both back and front performance, see

 

https://www.quora.com/Where-should-an-air-filter-be-placed-relative-to-the-fan-for-best-efficiency/answer/Thomas-Talhelm

 

 

[lsemprini]

24 minutes ago, Jimbo1964 said:

There are also nano-silver filters available here in LoS http://www.iaq-technologies.com/iaq-virus-keeper_filters-pm2-5/

 

Thanks.

 

That article directly claims that the nano-silver filters block PM2.5, and it would be great if it works, but I couldn't find any corroboration of that anywhere from Wiki or any other source. 

 

I am a bit skeptical simply because the material is so thin, almost transparent.

For example the Wiki page doesn't mention it and focuses on the washing machine application (about which there is controversy that such filters might cause more pollution in dumps than they correct in clothing!): https://en.wikipedia.org/wiki/Silver_Nano

 

Has anyone used that material and tested its performance with a PM2.5 meter?

 

[vivid]

2 hours ago, sfokevin said:

How difficult would it be to attach a 3M filter to one of these?...

 

 

 

Easy peasy, as long as the fan motor doesn't overheat, just pop it over the air intakes and it'd stick.    ????????

[vivid]

One more recommendation.

 

Ok, so the CADRs for the DIYs aren't exactly high and you are unimpressed. 

 

For connoiseurs of clean air willing to spend, it should be around 13k baht for the Xiaomi MAX once Lazada TH stocks it in a few months.

Just in time for next year's BKK or N Thailand haze.

 

1000 m3/hr of bad ass air shifting power.  And yes, it has a somewhat small footprint of just 35cm x 35cm, so you can pop in 2 into the living room and the wife hopefully woul;dn't notice it.  ????

 

https://detail.tmall.com/item.htm?spm=a230r.1.14.29.2021642b4a0E8T&id=563390611385&ns=1&abbucket=12&skuId=3546547520669

 

[THAIJAMES]

12 hours ago, vivid said:

One more recommendation.

 

Ok, so the CADRs for the DIYs aren't exactly high and you are unimpressed. 

 

For connoiseurs of clean air willing to spend, it should be around 13k baht for the Xiaomi MAX once Lazada TH stocks it in a few months.

Just in time for next year's BKK or N Thailand haze.

 

1000 m3/hr of bad ass air shifting power.  And yes, it has a somewhat small footprint of just 35cm x 35cm, so you can pop in 2 into the living room and the wife hopefully woul;dn't notice it.  ????

 

https://detail.tmall.com/item.htm?spm=a230r.1.14.29.2021642b4a0E8T&id=563390611385&ns=1&abbucket=12&skuId=3546547520669

 

one thing that stopped me from getting these bigger models is because I could never get information on the replacement filters. Can you use the same filters as the smaller models and if so that would mean that the only difference is the the fans in them?

[vivid]

1 hour ago, THAIJAMES said:

one thing that stopped me from getting these bigger models is because I could never get information on the replacement filters. Can you use the same filters as the smaller models and if so that would mean that the only difference is the the fans in them?

Nope, Xiaomi has not released the filters for sale on Taobao yet.  But rest assured that they will be on sale as Xiaomi is a very big coy.

 

There are 3rd party ones.  These are likely to be of the quality of either the SmartAir HEPA filters or those cheap PP media DIY filter that i am using now.

 

A set of 2 costs 1650 baht in China.  Likely to be slightly lower in price once the originals come out.

 

I think there is a mistake on the size of the HEPA.  It looks thick, but it's not 153mm thick.  More like 60-70mm or so.  But yeah it's thicker than most of other AP's HEPA.  You'd need that to do 1000m3/hr as the L and H is only 551 x 372mm else the air velocity flowing past the HEPA media is going to be too high and the CADR hits a plateau no matter how how much further you push the fan motor.

 

This store is not the official Xiaomi store on Tmall

https://detail.tmall.com/item.htm?spm=a230r.1.14.196.74122b49DgvTKj&id=586258610467&ns=1&abbucket=12

 

 

 

 

[vivid]

Oh yeah i forgot that there is another thing that you guys can DIY.  

 

There are are some DIY models in China and also a model called Smartmi that is just basically operating like a cleanroom or hospital quarantine room positive pressure FFU (Fan FIlter Unit).  So basically the indoor air leaks out through all the leaks in the house. 

 

You can DIY a filter box that has 2 layers of filter grades (all available on TB but not sure about LAzada, or you can get some in via 3rd party TB forwarders in Thailand), actually 3 if you include the prefilter.  So it's like prefilter-G5 grade-H11 grade.  It's gotta be cheap though, i don't have practical experience but i suspect the filter's gotta be changed more frequently than APs placed in the house.

 

In this case, you don't have much issues with CO2 or other indoor air quality contaminants building up.

 

https://item.taobao.com/item.htm?spm=a230r.1.14.60.74d44a56yOIDiK&id=520291034609&ns=1&abbucket=12#detail

 

 

Semi-0IY

 

 

 

 

[vivid]

Actually for HEPA filters, you really need higher pressure fans rather than the normal PC bladed fans.

 

How about using a centrifugal blower, adapt the intakes to the center of the Xiaomi centre portion.  Then get a hose and run the output of the centrifugal fan and run it into the house.   

 

This would be positive pressure already.  With just 1 of this, you really can keep the air quality of the whole house to be pretty clean, in single digits ug/m3.  Additional benefit is very low CO2 concentration.  You do not need heaps of airflow m3/hr going past the filter as this is a positive pressure setup.

 

https://www.aliexpress.com/item/1-Pcs-Brushless-DC-Cooling-Blower-Fan-9733s-3-Wires-12V-97x97x33mm/1670909164.html?spm=2114.search0104.3.226.38fa2178VCC4l2&ws_ab_test=searchweb0_0,searchweb201602_9_10065_10068_319_10059_10884_317_10887_10696_321_322_10084_453_10083_454_10103_10618_10307_537_536,searchweb201603_16,ppcSwitch_0&algo_expid=5c064089-4f0c-43a1-b6b6-f3fae7c11ca9-33&algo_pvid=5c064089-4f0c-43a1-b6b6-f3fae7c11ca9&transAbTest=ae803_5

 

 

 

[vivid]

Also, the wind is predominantly SW direction now.  You'd need to find out in your apartment which window is usually getting wind into the house and you site the contraption there.   The wind needs to be helping you instead of you going against the wind.

Get a variable speed controllable centrifugal fan so that you can set it up to have the lowest airflow to maintain a decent air quality in the house.

You really just need very little positive pressure to keep it going. 

 

Get a lot of airflow going, and you'd be wasting the lifespan of the HEPA filter.  And anyway, don't expect the filter to last for > 1 season.  For this year's season from start to finish, probably you might even be aiming to be using up 2 filters.  But that's alright for a whole house system, instead of getting say 4 pieces of Xiaomi 2S.

[vivid]

If you have a patio or balcony, you could easily site the setup there.  Just use some sticky tape and tranparent plastic sheet, that's about it.  

 

The thing is, the xiaomi filter needs to be "outside", exposed to the external environment, because the prefilter is there.  So there might be an issue with rainproofing it, though i guess being in the dry season it's not exactly a very big issue.

 

 

For those hardcore folks, use this positive pressure setup with variable controllable fan speed  in conjunction with your 2-4 units of Xiaomi 2S or other APs.   You could almost get to around 0 ug/m3, if my guesstimation and experience is correct.  1-2 ug/m3 on the meter is not an issue, i always get that easily.

 

Pretty hardcore stuff. 

 

But if you are doing AC (I mean it's hot out there during day time), then it might waste a bit of energy coz the cool air would be exhausted out as well.  For that you'd need to fine tune it so that the intake air into the house is just kept at a minimum level so that just a bit of postiive pressure is maintained to keep the haze from infiltrating the house.

[lsemprini]

5 hours ago, vivid said:

Actually for HEPA filters, you really need higher pressure fans rather than the normal PC bladed fans.

 

How about using a centrifugal blower, adapt the intakes to the center of the Xiaomi centre portion.  Then get a hose and run the output of the centrifugal fan and run it into the house.    

 

All great ideas; keep 'em coming.

 

For my particular project I wanted to target people who could not afford any fan other than the bladed floor/desk fan they already own but this is interesting for those who have more resources.

 

 

[vivid]

3 minutes ago, lsemprini said:

All great ideas; keep 'em coming.

 

For my particular project I wanted to target people who could not afford any fan other than the bladed floor/desk fan they already own but this is interesting for those who have more resources.

 

 

I think the centrifugal fans ought to be pretty cheap.....just need to spend time to find them.  And the correct ones.  BTW the above picture is just an illustration.  I think 12V 0.7A is a bit too low on power.  ????   Get a higher power DC unit, get some voltage control in it.

 

In fact i can almost swear that you can find them at second hand / recycling shops. 

[THAIJAMES]

Vivid thank you so for your excellent ideas.

Since a lot of us already have indoor air filters but would like to introduce outside fresh air that's been filtered your ideas are excellent.

 

My house is too big to be filtered all at once and I have individual filters for each room.

 

it would look weird to have a contraption blowing outside air drilled into the walls.

 

What about just putting filterette filter sheet in air cracks?

 

Or a tiny solar powered little fan motor with HEPA filter that you can use a tiny tube between the cracks ????

 

[vivid]

4 hours ago, THAIJAMES said:

Vivid thank you so for your excellent ideas.

Since a lot of us already have indoor air filters but would like to introduce outside fresh air that's been filtered your ideas are excellent.

 

My house is too big to be filtered all at once and I have individual filters for each room.

 

it would look weird to have a contraption blowing outside air drilled into the walls.

 

What about just putting filterette filter sheet in air cracks?

 

Or a tiny solar powered little fan motor with HEPA filter that you can use a tiny tube between the cracks ????

 

 

Actually if you are pretty certain that due to the predominantly SW-S-SSE winds daily which makes the winds in your house come in from a certain window/sliding door at your house, you could actually just stick a big piece of HEPA media to the sliding windows/doors and that means the incoming air is filtered naturally.  Just have to get some brain juices flowing to make it work and not pose too big an issue in operating the door/window for normal purposes in case you wanna get to the balcony or what.

 

The airflow getting past the HEPA media is not going to be high, but it should mean that the incoming "leaking" air is at say 30 ug/m3 instead of 350 ug/m3 during the worst periods like early morning till noon.   Then you can just fire up 1 or 2 pieces of Xiaomi 2S around the house and you are golden.

 

Of coz you gotta run a PM2.5 meter, not sure if there are ones that have alarms built in which allows you to set threshold alerts.  My CO2 meter has an alert feature.   This way if the wind blows the other way round suddenly, then you get notified and close the windows/doors.

 

PP HEPA media.  This type is the lower grade one with around 92% and higher airflow resistance.  But it gotta be cheap for this purpose as it does not have the mesh prefilter that the Xiaomi round filter has built-in.

 

https://item.taobao.com/item.htm?spm=a230r.1.14.20.7fcd1960i1lMUf&id=546339456201&ns=1&abbucket=12#detail

 

40rmb/6 usd for 5pcs 50cm x 30cm sheet.  For those who are getting from TB often via 3rd party then it should be of no problem. 

 

 

[vivid]

The whole list here, enjoy reading.

 

https://s.taobao.com/search?q=HEPA+纸&type=p&tmhkh5=&spm=a21wu.241046-cn.a2227oh.d100&from=sea_1_searchbutton&catId=100

 

 

[vivid]

BTW, do not use these sheets on your airconditioner FCU.  You'd risk screwing up the FCU.  The air resistance pressure drop is way too high for the FCU to handle. 

[THAIJAMES]

2 hours ago, vivid said:

 

Actually if you are pretty certain that due to the predominantly SW-S-SSE winds daily which makes the winds in your house come in from a certain window/sliding door at your house, you could actually just stick a big piece of HEPA media to the sliding windows/doors and that means the incoming air is filtered naturally.  Just have to get some brain juices flowing to make it work and not pose too big an issue in operating the door/window for normal purposes in case you wanna get to the balcony or what.

 

The airflow getting past the HEPA media is not going to be high, but it should mean that the incoming "leaking" air is at say 30 ug/m3 instead of 350 ug/m3 during the worst periods like early morning till noon.   Then you can just fire up 1 or 2 pieces of Xiaomi 2S around the house and you are golden.

 

Of coz you gotta run a PM2.5 meter, not sure if there are ones that have alarms built in which allows you to set threshold alerts.  My CO2 meter has an alert feature.   This way if the wind blows the other way round suddenly, then you get notified and close the windows/doors. 

 

PP HEPA media.  This type is the lower grade one with around 92% and higher airflow resistance.  But it gotta be cheap for this purpose as it does not have the mesh prefilter that the Xiaomi round filter has built-in.

 

https://item.taobao.com/item.htm?spm=a230r.1.14.20.7fcd1960i1lMUf&id=546339456201&ns=1&abbucket=12#detail

 

40rmb/6 usd for 5pcs 50cm x 30cm sheet.  For those who are getting from TB often via 3rd party then it should be of no problem. 

 

 

sounds like a good idea but why would you have to worry about the wind direction if it blows the other way then just means that less air is coming in. Unless you have any other windows open.

 

Also using home automation I can easily read the readings off the sensor and do something with it.

 

What about the micro tube and microfilter micro blower idea? Just to raise the CO2 level.

[Marcous]

Here's some more filter porn for you.

 

This is 3M filtrete. I just place it over the air intakes at the top of the aircon.

 

I'm not using the cooling function, just the fan on it's lowest setting. It may put some strain on the motor control unit but I very much doubt it.

 

The middle piece was on there for 5 days of continuos use. The other 2, about 3-4 days.

 

I don't have a meter but when I open the bedroom door in the morning I can smell the smoke. So it's doing something.

 

I think one roll will last about 3 weeks. Don't remember the price but think it was about 500 baht.

[Marcous]

2 hours ago, THAIJAMES said:

Actually if you are pretty certain that due to the predominantly SW-S-SSE winds daily which makes the winds in your house come in from a certain window/sliding door at your house, you could actually just stick a big piece of HEPA media to the sliding windows/doors and that means the incoming air is filtered naturally.  Just have to get some brain juices flowing to make it work and not pose too big an issue in operating the door/window for normal purposes in case you wanna get to the balcony or what.

You've got me wondering now. Most Thai houses, like mine , have a mesh mosquito door. See below.

 

Now it would be pretty easy to block up the main bulk of it with whatever ( aluminiun, cling film, paper etc)  Then cover the remaining portion with a filter of some sorts. This would solve the 'stuffiness' from lack of fresh (smoke filled) air.

 

[vivid]

4 hours ago, THAIJAMES said:

sounds like a good idea but why would you have to worry about the wind direction if it blows the other way then just means that less air is coming in. Unless you have any other windows open.

 

Also using home automation I can easily read the readings off the sensor and do something with it.

 

What about the micro tube and microfilter micro blower idea? Just to raise the CO2 level.

Yes, if it blows the other way round then the air quality would drop instantly.  So there is a downside to this.  You gotta make sure you know very well the airflow in your house and see if it's workable.

[vivid]

1 hour ago, Marcous said:

You've got me wondering now. Most Thai houses, like mine , have a mesh mosquito door. See below.

 

Now it would be pretty easy to block up the main bulk of it with whatever ( aluminiun, cling film, paper etc)  Then cover the remaining portion with a filter of some sorts. This would solve the 'stuffiness' from lack of fresh (smoke filled) air.

 

Now if the wind is usually coming in from this mosquito net door, then it'd be real easy.  

But do use the HEPA media, big pieces of it.  3M filtrete won't really work.

 

Happy searching for it.

[sfokevin]

https://www.lazada.co.th/products/diy-xiaomi-air-purifier-homemade-air-cleaner-hepa-filter-remove-pm25-smoke-odor-dust-formaldehyde-tvoc-for-home-and-car-i307042119-s534928019.html?spm=a2o4m.searchlist.list.75.37cc571130MA2Q&search=1

 

[lsemprini]

On 4/8/2019 at 1:11 PM, sfokevin said:

https://www.lazada.co.th/products/diy-xiaomi-air-purifier-homemade-air-cleaner-hepa-filter-remove-pm25-smoke-odor-dust-formaldehyde-tvoc-for-home-and-car-i307042119-s534928019.html?spm=a2o4m.searchlist.list.75.37cc571130MA2Q&search=1

 

Thanks.  "Vivid" linked to a whole family of those types in post #11 of this thread.  The one you pictured here seems to be the one from that family that is most readily available in Thailand via Lazada:

 

https://www.lazada.co.th/products/diy-xiaomi-air-purifier-homemade-air-cleaner-hepa-filter-remove-pm25-smoke-odor-dust-formaldehyde-tvoc-for-home-i304938467-s528114011.html?spm=a2o4m.searchlist.list.3.62577a01Tcc7y0&search=1

 

I am quite skeptical of this design because the fan is so small.  It might take 12 hours to bring a room to the same level that a more powerful fan (either DIY or commercial) could do in 2 hours.

 

Has anyone actually tried one of these and measured with a meter?

 

 

 

[gamesgplayemail]

hello, is it as good as buying a real air purifier ?

 

in case real purifiers are better, can you confirm that xiaomi pro is the best pair purifier for 5000 thb ? or which one should i buy ? Thank you.

 

https://www.lazada.co.th/catalog/?q=xiaomi+purifier+pro

 

https://shopee.co.th/search?keyword=xiaomi purifier pro

[elektrified]

3 hours ago, gamesgplayemail said:

hello, is it as good as buying a real air purifier ?

 

in case real purifiers are better, can you confirm that xiaomi pro is the best pair purifier for 5000 thb ? or which one should i buy ? Thank you.

 

https://www.lazada.co.th/catalog/?q=xiaomi+purifier+pro

 

https://shopee.co.th/search?keyword=xiaomi purifier pro

No need to spend money like the examples you listed. You can easily make your own as stated earlier in the thread. We built 3 of them last year and got the Xiaomi filters when they had the 50% sale. Build them early because everywhere runs out of stock of parts during the burning season.

[beau thai]

13 hours ago, elektrified said:

No need to spend money like the examples you listed. You can easily make your own as stated earlier in the thread. We built 3 of them last year and got the Xiaomi filters when they had the 50% sale. Build them early because everywhere runs out of stock of parts during the burning season.

I bought a Xiaomi last smokey season and I am very happy with it. Other friends say the same and it seems to be th go-to kit unless something better is produced next year... Its quiet and effective

[lsemprini]

On 10/22/2019 at 7:08 PM, gamesgplayemail said:

hello, is it as good as buying a real air purifier ?

 

in case real purifiers are better, can you confirm that xiaomi pro is the best pair purifier for 5000 thb ? or which one should i buy ? Thank you.

 

https://www.lazada.co.th/catalog/?q=xiaomi+purifier+pro

 

https://shopee.co.th/search?keyword=xiaomi purifier pro

 

The 1-fan DIY design shown in the OP is not as powerful as most Xiaomi models, however in terms of the overall parts cost and ALSO the amount of pollution cleaned per baht, it is definitely cheaper.

 

The 2-fan DIY design shown in the OP, while noisy and not pretty, actually cleans more pollution PER HOUR than the commercial unit I was comparing with (which wasn't a Xiaomi but I think the commercial units are pretty similar to each other) in addition to being much, much cheaper.

 

So it depends on your desired trade-off of cost, noise, space, effectiveness, ... and also whether you already have a fan or two sitting around and like arts and crafts projects with cardboard and tape.

 

For more info see https://slice-of-thai.com/air/

 

TELL SHOP OWNERS / THAI ENTREPRENEURS THAT THERE IS A WAY TO MAKE SOME GOOD MONEY: this would be a good time to order a bunch of real HEPA filters for the coming incineration in February!  I want to make sure as many enterprising hardware stores and other business folks get the word NOW and stock up on those filters, so that when the actual pollution comes in February (and everyone is running around unprepared looking for a quick fix) there will be a good supply in Thailand available for quick order.  We want to avoid the situation of the last few years, where 100% of Thai inventory is out of stock by the end of February and the only ways of ordering (from China) take 1+ months.