Professional dehumidifiers: size in L/day
Seven machines rated from 26 to 335 L/day, plus their consumables. An industrial dehumidifier is chosen on the real water load of the crop and on its efficiency in litres per kilowatt-hour, never on a stated covered area.
Water load, the only valid basis for calculation
What irrigation supplies comes back almost entirely into the air, through transpiration. Reckon on 1 to 5 litres per square metre per day depending on species, growth stage and radiation: a 100 m² room in full vegetative growth may call for more than 300 litres of extraction a day, a propagation room ten times less. The covered areas printed on some data sheets cannot be verified and are sometimes wrong by an order of magnitude.
A capacity only means something with its test condition
There is no mandatory test condition in the European Union for a dehumidifier: these appliances are excluded from energy labelling and from ecodesign. Three reference standards therefore coexist, and a unit changes capacity depending on which one the manufacturer adopts.
| Test condition | Used by | Relative capacity |
|---|
| 30 °C / 80% RH, so-called saturation | entry-level ranges | 100% |
| AHAM DH-1-2008: 26.7 °C / 60% RH | Quest figures and US data | about 62% |
| DOE 2019 and AHAM DH-1-2022: 18.3 °C / 60% RH | US reference standard | about 37% |
A unit quoted at 60 L/day under saturation conditions extracts in the order of 37 L/day at 26.7 °C / 60% RH, and 22 L/day at 18.3 °C / 60% RH. Comparing a “60 L” and a “26 L” without reading their conditions sometimes amounts to comparing the same machine twice. A second trap: at Quest, the model number is in US pints per day (1 pint = 0.4732 L), not in litres.
Efficiency in L/kWh, the only comparable criterion
Efficiency relates the litres extracted to the energy consumed, at a declared condition. It is what weighs on operating cost: a machine running fifteen to twenty hours a day all year costs more in electricity than its purchase price. Capacity and efficiency do not go together: at Quest, the 155 is quoted at 3.93 L/kWh against 3.40 L/kWh for the 706, which is much larger — a difference of generation, not a rule that small means efficient.
Integration
- Mounting: floor-standing, hanging — which frees productive floor area — or ducted, outside the growing zone. A room-layout decision.
- Heat rejected: a refrigerant machine heats the air it treats. Inside the room it adds its power to the heat balance; ducted, it discharges it elsewhere.
- Control: an integrated hygrostat on some models, a mandatory external controller on others, at 24 V. An integrated hygrostat measures at the appliance, not at the canopy.
- Condensate: direct gravity drainage. A removable 5 litre tank fills in under three hours on a 50 L/day machine.
- Operating range: 13 to 35 °C on the common models, up to 43 °C on the largest units; outside that range the machine ices up or trips to safety.
Refrigerant: the European timetable
These machines contain a refrigerant governed by Regulation (EU) 2024/573. R410A, still present in part of the installed base, has a global warming potential of 2,088: placing a new dehumidifier charged with it on the Union market will be prohibited by 1 January 2027 at the latest. Recent generations move to R454B, whose potential of around 466 still rules out calling it an environmentally benign refrigerant. Periodic leak checking applies above 2.4 kg of R410A, and any work on the circuit is a matter for a certified company.
This equipment ships on a pallet, lead time stated on the quotation. Filters, hanging kits and sensors are grouped in dehumidifier accessories and spare parts. The opposite need is covered by our humidifiers section, and humidity control is discussed in humidify or dehumidify, the complete guide. This section belongs to industrial climate control.
