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Comment by okasaki | Hacker News Reader

Or, you know, put a piece of paper on it to block the LCD.

Also, I thought air purifier filters aren't 'cleanable'. Like, you can't just hoover them.

Even if not cleanable, the machine isn't going to actually know if they need to be replaced or not. It will depend on how dirty the air was and how much stuff got filtered out. Normal air purifiers would have a reset option to reset the timer.

Indeed, but the OP says he's cleaned it several times, so it "should be good". What I'm saying is that you're not supposed to clean them.

Perhaps, but that's the owner's decision to make.

I mean, I guess? But that's just a thought-terminating cliche. You're not supposed to clean the filters because that's not how it works.

>the machine isn't going to actually know if they need to be replaced or not

The machine can know if it measures differential pressure across the filter. If the DP across the filter is too high (indicating a clogged filter), the filter needs to be replaced.

I know for a fact that my Levoit unit isn't that sophisticated because when it asks you to replace the filter there's simply a button which resets the filter life back to 100% that you're supposed to press after changing it - if it were actually doing anything clever to determine the state of the filter then you wouldn't have to tell it that it's been replaced, it would be able to tell on its own. I suspect it's nothing more than a timer which triggers the warning after running for some hardcoded number of hours.

Can this machine know that?

A machine could, but is this machine sophisticated enough to do that? Why do we play around with hypotethical scenarious where this warning message on another device might not be shitty DRM?

Are you stating that this specific machine actually does this, or are you just theorycrafting that a hypothetical machine could do this?

I just went through the product’s FCC certification photos which gives you nice pictures of the product internals.

AFAICT, there were no readily obvious DP sensors to be found.

There's usually a pre-filter on the outside which stops larger particles from entering the actual HEPA filter, and you can clean that at least.

Yes, certainly, but the OP describes it as a replace filter warning, which is usually for the actual filter.

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