Choosing and running humidifiers and dehumidifiers: output ratings, target humidity, tank sizing, white dust, and mould risk.
Output in gallons per day is the capability. Tank size only tells you how often you refill. And the room-coverage figure on the box cannot account for the one variable that decides everything: how leaky your house is.
A portable dehumidifier’s pint rating is measured at 65 °F and 60% humidity under federal rule. That one fact explains why a “50-pint” unit today was a “70-pint” unit a few years ago, and why basement sizing needs care.
EPA puts the target at 30 to 50 percent and the ceiling below 60. The reason the ceiling exists is dew point: at 50 percent and 70 degrees, any surface below 50 degrees starts collecting water.
Three mechanisms, three different sets of consequences. One cannot over-humidify a room, one puts your tap water’s minerals into the air, and one sterilizes the output and costs the most to run.