Air purifier: How can I tell if it's working?

Factual Questions
1

I bought a Bionaire air purifier last month to help get rid of the dusk that comes from keeping the windows open in the summer.

Problem is I don’t know if it is working. This particular unit has a vent on the front (sort of like the air vent in a car) and a intake on the side. While the output from the vent is very strong (three levels, in fact), the input on the side is very weak. If my hand is wet, I can sort of feel some air moving in, by not much.

Is this normal? If so, how does this thing collect dust and stuff into its filters? I would have assumed that it requires some kind of moderate suction.

2

Clean the filters, man.

Then light a smoke and blow it into the intake. That oughtta tell you if it’s filtering or not.

–Tim

3

Well, think about conservation of mass here a bit. Whatever comes out the outlet had to come from somewhere. It either is coming in the inlet vent or else leaking into the system somewhere - and possibly bypassing the filter in doing so.

It is much more difficult IME to feel air at an inlet, as opposed to air at an outlet. It’s a very subjective thing, and it varies a bit depending on what the ratio of the areas on the inlet and the outlet side are.

4

Anthracite is essentially correct. The reason you don’t feel the air going in as strongly as the air coming out is because you are feeling the same volume of air at 2 different pressures. The air going in is flowing through a large pipe (the room) and the air coming out just left a small pipe. Homer’s test should make it clear whether the purifier is working or not.

5

Yes, yes. All correct so far.

I’d just add that someone concerned with outdoor dust probably doesn’t have “a smoke” handy.

Use the smoke from an extinguished candle.

Also, just inspect the filter. If you’ve been running it even for just a few days, it should show some discoloration.