Crawl Space Dehumidifiers

Size based on crawl space volume, not just square footage.

Calculate Volume:
Length (ft) × Width (ft) × Height (ft) = Cubic Feet

Capacity Guidelines:

• Up to 11,000 cu ft: 60 pint/day capacity
• Up to 15,000 cu ft: 85 pint/day capacity
• Over 15,000 cu ft: Multiple units or commercial-grade equipment

Examples:

• 800 sq ft × 3 ft height = 2,400 cu ft → 60 pint adequate
• 1,500 sq ft × 4 ft height = 6,000 cu ft → 60 pint adequate
• 2,000 sq ft × 5 ft height = 10,000 cu ft → 60 pint adequate
• 3,000 sq ft × 5 ft height = 15,000 cu ft → 85 pint required

Adjustment Factors:

• Very humid climates: size up one capacity level
• Standing water issues: address drainage first, then size up
• Multiple separate areas: may need multiple smaller units for better coverage

Pro Tip: Slightly oversizing is better than undersizing—unit cycles less frequently but maintains target humidity more effectively.

Crawl space dehumidifiers require different features than residential basement models.

Essential Features:

Built-in Condensate Pump:

• Eliminates gravity drain requirements
• Allows flexible positioning
• Pumps water uphill 15+ feet or horizontally 50+ feet

All-Aluminum Coils:

• Resists corrosion in high-humidity environments
• Copper and steel coils deteriorate in crawl space conditions
• Extends unit lifespan significantly

Digital Controls:

• Precise humidity target settings (typically 50-55%)
• Humidity level display for monitoring
• Easy adjustment without entering crawl space

Automatic Restart:

• Preserves settings after power outages
• Essential for unattended operation
• Prevents humidity spikes during outages

Low-Temperature Operation:

• Functions in 40-45°F+ range
• Critical for winter operation
• Auto-defrost prevents ice buildup

Optional but Valuable:

Remote Control Capability: Monitor and adjust from upstairs without crawl space entry

Ducting Compatibility: Direct airflow to problem areas or multiple zones

High-Quality Filtration: MERV-10+ filters improve air quality

Yes—vapor barriers and dehumidifiers work together, not independently.

What Vapor Barrier Does:

• Blocks ground moisture evaporation (10-15 gallons/day potentially)
• Creates sealed environment essential for humidity control
• Foundation of encapsulation system

What Vapor Barrier DOESN'T Do:

• Remove moisture already in the air
• Extract humidity that enters through foundation walls
• Handle condensation on cool surfaces
• Remove moisture from outdoor air infiltration through minor leaks

Why Both Are Essential:
Even with perfect vapor barrier installation, moisture still enters from:

• Foundation wall pores (concrete/block are porous)
• Minor air leaks around doors, vent covers, or penetrations
• Plumbing condensation
• Ground moisture migrating through concrete

Without Dehumidifier: Humidity rises to 70-80%+ causing mold growth, wood rot, and musty odors—defeating encapsulation purpose.

With Dehumidifier: Maintains 50-55% humidity where mold cannot grow, wood stays dry, and air quality remains healthy.

Complete Encapsulation System:

1. Vapor barrier blocks ground evaporation
2. Sealed vents prevent outdoor air infiltration
3. Dehumidifier removes remaining moisture sources
4. Result: Controlled environment preventing moisture damage

Built-in pumps provide flexible drainage options—no gravity drain required.

Drainage Options:

1. To Exterior:

• Run condensate line through foundation wall
• Discharge onto ground away from foundation (10+ feet)
• Most common and simplest option

2. To Sump Pump:

• Connect to existing sump pump basin
• Sump handles final discharge
• Good when sump already installed for groundwater

3. To Utility Sink or Floor Drain:

• Pump upstairs to basement utility sink
• Use existing floor drains if available
• Convenient but requires longer line runs

4. To Exterior Drain System:

• Connect to perimeter drain piping
• Integrate with existing drainage infrastructure

Pump Capabilities:

• Typical lift: 15 feet vertically
• Horizontal distance: 50+ feet
• Standard ½" condensate line

Installation Best Practices:

• Slope condensate line away from unit (prevent backflow)
• Insulate line if routing through cold areas (prevents freezing)
• Secure line to prevent disconnection
• Discharge away from foundation (prevent water return)

No Convenient Drain? Built-in pumps solve this—route to wherever drainage exists, even uphill or across long distances.