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Old 25-04-2019, 07:33 PM   #2851
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Join Date: Jun 2001
Posts: 55,785
Thank you very much for your detailed reply, this information is very useful. It makes sense there is a risk of the transformer malfunctioning, I think I will now probably abandon the idea of buying a 120V AP.

I am an expat living in Hong Kong, unfortunately my Chinese language ability is not that great so it can be difficult to understand Chinese reviews.

You are correct that Xiaomi 2S is available in HK retail, it is widely available locally for HKD $1,099 (approx. USD $140) which is obviously very cheap. Today I went to an electronics store to look at the Xiaomi 2S, I am happy with the price but have some concerns about the quality. Specifically, I am concerned about the quality of the HEPA filters, are they on a par with leading international brands such as Coway / Philips?

One other final option I am considering is buying the Blueair Blue Pure 221 from Germany. Since Germany uses the same Voltage/Frequency as HK/SG, there is no need to use a transformer. I have found an online retailer in Germany which sells this AP for EUR 316. They can deliver directly to HK for just EUR 35, so the total cost + delivery would be EUR 351, which is approx. USD $390.

From my research it seems the Blueair Blue Pure 221 is basically the 230V version of the Blueair Blue Pure 211, which is the highest ranked air purifier amongst all 36 reviewed and tested by US website Consumer Reports. Has anyone here ever used this AP?

Any thoughts on whether I should go for the Xiaomi or the Blueair?

Just go for the Xiaomi. All these filters can do 0.3 microns no issue.
The CADR (Clean Air Delivery Rate) of the Xiaomi 2S and Pro are 310 m3/hr and 500 m3/hr respectively. That is the spec to look out for, and after that would be things like noise level and then power consumption.

The 2S and Pro are pretty ok after you dial down the speed in the app control, just that in max fan speed mode they are very loud, louder than other APs in max fan speed mode. However the thing is that these APs are pretty small in size, so if you are talking about device volume : noise ration, the performance is still decent. And also due to the its taller stance and small foot print, it makes sense in a small apartment in Singapore or HK.

There is a small -ve of the Xiaomi 2S and Pro, actually any Xiaomi air purifier. Their Auto fan mode doesn't really work, coz they set the higher fan speed to kick in at too high a PM2.5 ug/m3 concentration level.
It's a quirk of the AP, can't be helped. Seriously, quite a few other APs also are of this nature, so isn't a big deal.
Most of us just use manual speed, really not a biggie in real life usage.

Forget about the Blueair. The filters are extremely expensive.
The Blueair 221 has a CADR of 590 m3/hr, so it'd be like a Xiaomi Pro competitor. The good thing about the 221 is that it is relatively less noisy than the Pro (56 dBA for the 221 vs 69dBA for the Xiaomi Pro, which is bloody loud).

The Blueair 221 is 33 x 33cm x 52cm. Xiaomi Pro is 26 x 26 x 73cm.

There is another point called the Formaldehyde CADR, that is another point to consider for other pax having this specific need due to other reasons (basically VOC pollution and protection, touched before in the past 5 pages due to a very specific case that happened in Singapore).
But pls if anyone is having some formaldehyde outgassing issue, the correct way to treat it is not to have big ass APs with really high formaldehyde CADR (eg the X352 X83C Plus) but you'd need to get the temperature of the room to relatively high levels to speed up the outgassing.
1-hr ug/m3 + PSI
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