Quick answer: At 20 °C / 60 % RH, rated removal divided by rated power across our RY desiccant range gives about 0.6–1.0 litres per kWh, roughly 1.0–1.6 kWh per litre. Most electrical power goes to the reactivation heater to drive absorbed water out of the rotor; fans and the rotor drive use the rest.
The fans are the process fan and reactivation fan. An electrically reactivated desiccant dehumidifier uses more energy per litre than a refrigerant dehumidifier in warm air, but in cold rooms or for low dew points the desiccant unit is often the only practical option. Using waste heat, steam or hot water for reactivation and controlling heat to the load cut running cost sharply.
Quick answer
- Energy users: reactivation heater (largest), process fan, reactivation fan, rotor drive.
- Our RY range: about 0.6–1.0 L/kWh at 20 °C / 60 % RH.
- Cheapest kWh: waste heat or steam for reactivation, and modulated heat at part load.
Where the energy goes
| Component | Share of power | Notes |
|---|---|---|
| Reactivation heater | Usually the majority | Heats reactivation air to drive water off the desiccant |
| Process fan | Moderate | Depends on airflow and duct pressure |
| Reactivation fan | Small | Smaller airflow |
| Rotor drive | Very small | Slow-turning motor |
The theoretical minimum is set by the heat needed to evaporate the water (about 0.68 kWh per litre) plus the heat of adsorption and the heat to warm the air and rotor, so real systems need more than 0.68 kWh per litre.
Our RY range: rated removal and power
All at 20 °C / 60 % RH:
| Model | Removal | Rated power | L/kWh | kWh per litre |
|---|---|---|---|---|
| RY-100M | 12 L/day | 0.69 kW | about 0.72 | about 1.4 |
| RY-200M | 15 L/day | 0.73 kW | about 0.86 | about 1.2 |
| RY-300M | 48 L/day | 2 kW | about 1.0 | about 1.0 |
| RY-600M | 72 L/day | 4.5 kW | about 0.67 | about 1.5 |
| RY-1000M | 180 L/day | 11 kW | about 0.68 | about 1.5 |
| RY-3000M | 456 L/day | 30 kW | about 0.63 | about 1.6 |
Rated power includes the electric reactivation heater. Full data on our desiccant dehumidifier page.
Running cost example
Daily cost = rated power (kW) × running hours × electricity price
A RY-1000M (11 kW) running 20 hours a day at €0.15 per kWh: 11 × 20 × 0.15 ≈ €33 per day, removing up to about 150 L at rated conditions.
At part load, many units cycle or modulate the heater, so actual consumption is often lower. See industrial dehumidifier running cost.
Desiccant vs refrigerant energy
| Condition | Typically more efficient |
|---|---|
| Warm room (above about 18 °C), target 40–60 % RH | Refrigerant (our RYCF range: about 2.4–2.7 L/kWh at 30 °C / 80 % RH) |
| Cool room (5–15 °C) | Often close; refrigerant capacity falls and defrost adds energy |
| Below about 5 °C, or dew point below about 5 °C | Desiccant: refrigerant cannot do the job well |
Rating conditions differ (30 °C / 80 % vs 20 °C / 60 % RH), so compare at your own condition. See refrigerant vs desiccant.
Ways to cut desiccant energy use
- Seal the room: less leakage means less water to remove.
- Control on dew point or RH so the unit runs only when needed.
- Modulate reactivation heat to the load instead of full heat all the time.
- Use cheaper heat: waste heat, steam, hot water or gas burners on larger units; the US DOE has reviewed thermally activated desiccant systems (US DOE / UNT digital library).
- Pre-cool humid inlet air with a refrigerant coil for low dew-point duties.
- Recover heat from the reactivation exhaust where practical.
- Keep filters clean so fans don't waste energy and the rotor stays effective.
Questions to ask in an RFQ
- Total power at the design condition, with all fans and heater included
- Reactivation heat source options and temperature
- Heater control: on/off, staged or modulating
- Capacity and leaving dew point at your inlet condition
- Fan power at the installed duct pressure
FAQ
Frequently asked questions
How much electricity does a desiccant dehumidifier use?
Roughly 1.0–1.6 kWh per litre removed across our range at 20 °C / 60 % RH, mostly for the reactivation heater.
Are desiccant dehumidifiers energy efficient?
Less than refrigerant units in warm air, but often the only practical option in cold spaces or for low dew points.
How can I reduce desiccant dehumidifier running costs?
Seal the space, control to the load, modulate reactivation heat, and use waste heat or steam where available.
Sources
- ASHRAE Handbook—HVAC Systems and Equipment, Desiccant dehumidification.
- US DOE-funded report on thermally activated desiccant technology (UNT Digital Library).
- Product data: Yakeclimate RY series specifications.
