Equipment and Airflow
Equipment families
- Air movers: axial and centrifugal, rated in CFM and velocity; centrifugal units produce the static pressure needed for ducted or cavity work.
- Refrigerant dehumidifiers, including LGR: efficient in warm air, with capacity dropping as inlet air cools and dries.
- Desiccant dehumidifiers: strong in cool, low-humidity conditions and cavity injection; they add heat to process air.
- Air scrubbers and negative air machines with HEPA for Category 3 and mold work.
- Specialty tools: floor drying mats, wall cavity systems, injection kits.
Airflow principles
Air movers strip the saturated boundary layer from wet surfaces. Angle the discharge 15–45° to the surface to create a sweeping, swirling pattern, and keep the airstream unobstructed. A common starting point is one air mover per 10–16 linear feet of wet wall, adjusted for carpet pile, cavity drying and obstructions. Airflow without dehumidification only redistributes moisture within the structure.
Worked example
A 4,000 ft³ room with one 2,500 CFM air mover: 2,500 × 60 ÷ 4,000 ≈ 37 air changes per hour. That is ample mixing, but it says nothing about removal - the dehumidifier must still handle the evaporated load, and the psychrometric trend confirms whether it does.
Traps
Running a desiccant unit in hot humid air where refrigerant is more efficient; stacking contents against wet walls; aiming air straight at a surface and driving water deeper; ignoring clogged filters and dirty coils.