The musty smell is a gas given off by mold and bacteria growing on something damp, which is why air fresheners fail. Here is how to find the source, in order, and fix it for good.

A sizing chart by basement area and dampness in current 2019 DOE pints, the arithmetic behind it, worked examples from 500 to 2,000 sq ft, and the cases where one unit cannot do the job.

Diagnose the moisture source first, then size, drain and place the machine. A complete, honest guide to choosing and running a dehumidifier in a basement — including what one will never fix.