Just brought an air purifier and the manual stated I should keep it running all the time, I'm worried about its durability and the incur electricity bill? Should I just turn it off when no one is at home?
If you are concern about the increase in the electricity bill, fret not as most air purifiers use very little electricity even at max speed. For better air purifier energy management, you can look for an air purifier with Auto or Sleep mode that will automatically set the fan sleep to low when surrounding air quality is at an optimal level. Timer is a manual but effective way of managing the air purifier runtime. The major drawback of having an air purifier running perpetually is the mechanical filter like HEPA tends to wear out quickly so they will be a higher filter change frequency. But hey, that's what air purifier is for and would you rather inhale the allergens yourself or let the air purifier suck it up?
What we will recommend our customers to do is keep the air purifier running all the time when someone is at home and during your sleep. If you want to converse energy or fairly confidence in your indoor air quality would not turn bad while you're away, turn it off before you leave the house or set a timer for it to auto-shutdown when time is up. You can leave the air purifier on all day when is allergy season (summer) or there is a haze invasion.
So in short, you should leave the air purifier on all day even when you're not at home. Even if you don't, it's perfectly fine as well but make sure to turn it back on once you are back home.