Sizing Chart
Sizing Your Installation
Step 1: Evaluate Your Crawlspace or Basement
  1. Classify your crawlspace or basement
    • Tightly sealed (fully encapsulated or finished space)
    • Loosely sealed (vents closed off, plastic vapor barrier on floor or finished floor)
    • Unsealed (vented, bare earth floor, subject to periodic flooding) NOT RECOMMENDED – Dehumidification will not be effective in an unsealed space.
  2. Calculate your crawlspace or basement volume
    • To ensure proper humidity control, we recommend sizing your project by cubic volume rather than square area. To do this, measure width, length, and height of the space and multiply (W x L x H) to determine cubic volume. Be sure to include any offset spaces and areas under adjacent rooms in your calculations.
  3. Use the chart below to determine how many dehus are recommended for your installation. 

Step 2: Determine How Many Dehus You Need
Based on how you’ve evaluated your crawlspace or basement (see Step 1), choose the appropriate column to see how many PHD 200s you’ll need to condition the space.  

Number of PHD 200s Required
Size of Space
Tightly sealed
Loosely sealed
0–7,500 ft.3
0–212 M3
7,500–15,000 ft.3
212–424 M3
15,000–22,500 ft.3 
424–637 M3
22,500–30,000 ft.3
637–850 M3
30,000–37,500 ft.3
850–1062 M3
37,500–45,000 ft.3
1062–1274 M3
45,000–52,500 ft.3
1274–1487 M3
  1. To calculate the number of PHD 200s yourself, use these formulas: 
    • Tightly sealed spaces: cu. ft. divided by 7500 = no. of PHD 200s recommended
    • Loosely sealed spaces: cu. ft. divided by 3750 = no. of PHD 200s recommended
  2. Spaces that have deep alcoves, offsets, interior walls or other obstructions may require additional dehumidifiers and/or increased airflow to ensure adequate humidity control throughout the space.
  3. IMPORTANT: Remove any standing water and secure the space from recurring flooding before setting up the dehumidification system.