Selecting the correct size industrial dehumidifier is critical for maintaining optimal humidity control in commercial and industrial facilities. An undersized unit will struggle to reach target humidity levels, leaving your facility vulnerable to condensation, mould growth, and product damage, while an oversized system wastes energy through short cycling and excessive operating costs.
Understanding Dehumidifier Capacity Ratings
Dehumidifier capacity is measured in litres per day (L/day), but these ratings can vary dramatically depending on the test conditions used by manufacturers. A unit rated at 100 L/day at 30°C and 80% relative humidity might only remove 40-50 L/day at 20°C and 60% relative humidity, making direct comparisons between manufacturers misleading.
Understanding standardised rating systems is essential for accurate equipment selection. Two primary testing standards govern capacity ratings in Australia and internationally.
- AHAM Standard (DH-1): Tests at 26.7°C and 60% relative humidity, commonly used for smaller commercial units
- BS EN 810 Standard: European standard testing at 20°C and 60% relative humidity, widely adopted for industrial equipment
- Manufacturer specifications: Often tested at optimal conditions (30°C/80%RH) which rarely reflect real-world operating environments
- Saturation efficiency curves: Show performance across different temperature and humidity combinations for accurate sizing
Always request capacity data at your specific operating conditions rather than relying on peak performance figures. This ensures your selected commercial dehumidifier will deliver the required performance in your actual facility environment.
Step-by-Step Sizing Methodology
Accurate dehumidifier sizing requires a systematic approach that accounts for all moisture sources and environmental factors. Follow this comprehensive methodology to determine your facility’s precise dehumidification requirements.
- Calculate room volume (m³): Measure length × width × height of the space, accounting for equipment, storage, or structural obstructions that reduce effective air volume
- Identify moisture sources: Document all sources including infiltration, ventilation air, occupancy, production processes, and stored materials
- Set target relative humidity: Determine optimal humidity range based on application requirements (typically 40-60% for general storage, lower for sensitive products)
- Calculate total moisture load: Quantify moisture input from infiltration (building envelope), ventilation air, occupancy, and process-specific sources
- Apply safety factor: Multiply calculated load by 1.2-1.5x to account for peak conditions, equipment degradation, and future expansion
- Select equipment class: Choose between refrigerant, desiccant dehumidifiers, or hybrid systems based on operating temperature and target humidity levels
Professional psychometric calculations should be performed for critical applications or complex facilities. This methodology provides the foundation for accurate equipment selection and optimal system performance.
Moisture Sources in Commercial and Industrial Facilities
Understanding and quantifying moisture sources is fundamental to proper dehumidifier sizing. Each facility presents unique challenges that must be carefully evaluated and calculated.
| Moisture Source | Typical Load Range | Key Factors | Calculation Method |
|---|---|---|---|
| Infiltration | 2-8 L/day per 100m³ | Building age, construction quality, door/window seals | Air change rate × psychometric difference |
| Ventilation Air | 5-25 L/day per 100m³ | Fresh air requirements, outdoor humidity levels | CFM × humidity ratio difference |
| Occupancy | 1.5 L/person/day | Activity level, clothing, duration of occupancy | Number of people × metabolic moisture rate |
| Open Water Processes | 10-50 L/day per m² surface | Water temperature, air velocity, surface area | Evaporation rate calculations |
| Product Moisture | Variable | Material type, quantity, moisture content | Product specifications × drying curves |
| Industrial Processes | Highly variable | Process type, temperature, duration, materials | Process-specific engineering calculations |
Accurate quantification of these sources often requires monitoring existing conditions with data loggers over several weeks. Seasonal variations and peak operating scenarios must also be considered during the assessment process.
Sizing by Application
Different commercial and industrial applications have vastly different dehumidification requirements based on their specific operational needs and sensitivity to humidity. These guidelines provide starting points for capacity calculations across common facility types.
| Application Type | Capacity (L/day per 100m³) | Target RH Range | Special Considerations |
|---|---|---|---|
| Warehouse Storage | 8-15 L/day | 45-55% | Product sensitivity, packaging materials, turnover rate |
| Pharmaceutical Manufacturing | 20-40 L/day | 35-45% | Regulatory requirements, cleanroom classifications, hygroscopic materials |
| Food Processing | 15-30 L/day | 50-60% | Product type, packaging processes, wash-down procedures |
| Cold Storage (below 15°C) | 25-50 L/day | 80-90% | Defrost cycles, door openings, temperature fluctuations |
| Construction Drying | 40-80 L/day | Variable | Material types, ambient conditions, drying timeline |
| Data Centre | 10-20 L/day | 40-55% | Equipment heat loads, air conditioning integration, condensation prevention |
These capacity ranges assume typical Australian climate conditions and standard facility construction. Specific calculations based on actual facility conditions will provide more accurate sizing requirements for critical applications.
When to Use Multiple Units vs One Large Unit
The decision between multiple smaller units and a single large capacity system involves several operational and economic considerations. Both approaches offer distinct advantages depending on your facility’s specific requirements and operational priorities.
Multiple Smaller Units
- Advantages: Built-in redundancy, zone-specific control, easier installation and maintenance access, phased capacity deployment
- Disadvantages: Higher total equipment cost, more maintenance points, increased electrical connections, more floor space required
- Best for: Critical applications requiring 100% uptime, facilities with varying humidity zones, staged development projects
Single Large Unit
- Advantages: Lower initial cost, simplified controls, single maintenance point, often higher energy efficiency, minimal floor space
- Disadvantages: Single point of failure, limited zone control, potential oversizing during partial loads, complex installation requirements
- Best for: Cost-sensitive applications, uniform humidity requirements, facilities with reliable backup plans, space-constrained installations
Ducted dehumidifiers can bridge this gap by providing centralised capacity with distributed air delivery through existing HVAC systems. Consider your facility’s criticality, maintenance capabilities, and operational flexibility requirements when making this decision.
Australian Climate Considerations
Australia’s diverse climate zones significantly impact dehumidification requirements, with coastal and tropical regions presenting the greatest challenges. Understanding regional humidity patterns is essential for accurate system sizing and reliable year-round performance.
Northern Australia’s tropical climate creates consistently high humidity levels that can overwhelm undersized systems. Queensland and Northern Territory facilities often require 30-50% higher capacity than similar facilities in temperate southern regions.
- Tropical North (QLD, NT, Northern WA): Year-round high humidity, wet season peaks requiring maximum capacity from November to April
- Coastal Regions: Maritime influence creates persistent humidity challenges, salt air corrosion requires robust equipment selection
- Temperate South (VIC, SA, TAS): Seasonal humidity variations, winter condensation issues in heated facilities, summer peaks in coastal areas
- Arid Interior: Low baseline humidity but significant diurnal temperature swings creating condensation risks during cooling periods
Coastal facilities within 10 kilometres of the ocean require special consideration for salt spray resistance and enhanced capacity during onshore wind conditions. Design systems for peak humidity conditions rather than annual averages to ensure reliable performance during challenging periods.
Monsoon seasons in northern regions can sustain outdoor humidity above 85% for weeks, requiring continuous maximum capacity operation. Size equipment to handle these extended peak periods without compromising system reliability or component lifespan.
Industrial Dehumidifiers from Moisture Cure Commercial
Moisture Cure Commercial can assist with equipment selection and sizing for your facility, contact our team for a site assessment.
Talk to Moisture Cure Commercial
Proper dehumidifier sizing requires detailed analysis of your specific facility conditions, operational requirements, and local climate factors. With over 20 years of experience in commercial and industrial humidity control, Moisture Cure Commercial’s technical team can provide comprehensive sizing analysis and equipment recommendations tailored to your application.
Our sizing service includes psychometric calculations, equipment selection guidance, and installation recommendations to ensure optimal system performance and energy efficiency. Contact our technical specialists today to discuss your facility’s dehumidification requirements and receive professional sizing recommendations backed by decades of Australian commercial experience.
