Quick answer: A good industrial dehumidifier specification describes the job, not just a machine size. Include the room's target condition (RH and temperature, or dew point), the moisture load and where it comes from, the required capacity at your design condition (and the rating condition for catalogue figures), airflow and external static pressure for ducted units, power supply, drainage, controls and signals, materials for the environment, certificates for your market, and how the unit will be accepted. Suppliers can then quote comparable equipment, and you can compare their offers fairly.
Quick answer
- Always pair a capacity figure with its rating condition (for example 30 °C / 80 % RH).
- Ask for capacity and power at your own design condition.
- Specify installation, power, drainage, controls and acceptance up front.
Specification checklist
| Section | Specify | Example |
|---|---|---|
| Application | Space type, use, size | 2,000 m² warehouse, 8 m high, packaged goods |
| Target | RH at temperature, or dew point; tolerance | 50 ± 5 % RH at 15–28 °C |
| Design conditions | Worst-case indoor inlet and outdoor conditions | Indoor 28 °C / 70 % RH; outdoor 32 °C / 80 % RH |
| Moisture load | Total and sources | 40 kg/h: leakage, docks, people |
| Capacity | At the design condition, and the catalogue rating with its condition | ≥ 40 kg/h at 28 °C / 70 % RH; rated L/day at 30 °C / 80 % RH |
| Technology | Refrigerant or desiccant, or let the supplier propose | Refrigerant, low-temperature operation to 5 °C |
| Airflow and pressure | Airflow (m³/h) and external static pressure (Pa) for ducted units | 5,600 m³/h at 150 Pa |
| Installation | Floor, ceiling, ducted, outdoor; dimensions and weight limits | Ceiling-mounted, max 250 kg |
| Power | Voltage, phase, frequency; maximum current | 380–415 V, 3-phase, 50 Hz |
| Refrigerant | Type, if required | R290 or R410A |
| Drainage | Gravity or pump; connection size | Gravity drain, 25 mm |
| Controls | Built-in humidistat, remote sensor, BMS interface | Remote sensor; dry contacts for run/fault; RS485 Modbus |
| Materials | Coil coating, casing, corrosion class | Coated coils for coastal site |
| Noise | Maximum sound level at a stated distance | ≤ 65 dB(A) at 1 m |
| Certificates | For your market, for the exact model | CE (EU), UL (US), CB report to IEC 60335-2-40 |
| Documentation | Manuals, wiring diagrams, spare-parts list, test records | In English |
| Acceptance | Factory test and site commissioning criteria | Capacity test record; site RH trend for 7 days |
| Service | Warranty, spare parts, support | 2 years; recommended spares list |
Rating conditions: compare like with like
| Rating basis | Condition | Used for |
|---|---|---|
| Common catalogue rating (refrigerant) | 30 °C / 80 % RH | Most industrial and Chinese-made units |
| Older US rating (portable) | 26.7 °C (80 °F) / 60 % RH | Pre-2019 US consumer units |
| Current US rating (portable) | 18.3 °C (65 °F) / 60 % RH | US DOE test procedure since 2019 (10 CFR 430 Appendix X1) |
| Desiccant | Often 20 °C / 60 % RH | Desiccant rotor units |
Related: 10 CFR 430 Appendix X1.
The same unit's L/day can differ two- or three-fold between these conditions. Ask each supplier for capacity at your design condition.
Safety standards
Dehumidifiers with electric motors and refrigerant circuits are covered by the IEC 60335-2-40 safety standard for heat pumps, air conditioners and dehumidifiers (IEC 60335-2-40), used for CE and CB certification; UL 474 applies in North America. Units with flammable refrigerants such as R290 have additional charge and installation requirements under these standards.
Using the specification
- Send the same specification to every supplier.
- Ask them to fill in their figures next to yours and mark any deviation.
- Ask which figures are measured and which are calculated.
- Keep the specification as the reference for factory testing and commissioning.
See how to size a dehumidifier, how to choose a manufacturer and buying from China. Our industrial dehumidifiers list capacity, airflow, power and supply for each model.
FAQ
Frequently asked questions
What specifications matter most for an industrial dehumidifier?
Capacity at your design condition, airflow (and static pressure if ducted), power supply, operating temperature range, drainage and controls.
Why do capacity figures differ between suppliers?
Different rating conditions. Compare only at the same temperature and RH.
What certificates should an industrial dehumidifier have?
Those required in your market for that model: CE declarations in the EU, UL listing in North America, or a CB report to IEC 60335-2-40 for many other markets.
Sources
- US eCFR, 10 CFR Part 430, Subpart B, Appendix X1 (dehumidifier test procedure).
- IEC 60335-2-40; UL 474.
- ASHRAE, Fundamentals of psychrometrics.
