Quick answer: A dehumidifier collects its full rated amount only at the condition it was tested at, usually 30 °C/80 % RH for industrial units. In a typical damp room at 20 °C and 60 % RH, the air holds about 40 % of the water it holds at 30 °C/80 % RH, so daily collection is far below the label. Collection also falls once the room reaches its humidity setpoint and the unit starts cycling.
Quick answer
- The rating (L/day or pints/day) is a test result at one temperature and humidity.
- Cooler or drier air means less water per day from the same machine. This is normal.
- Output that drops suddenly at the same room conditions points to a dirty filter, iced coil or low refrigerant.
How much water is normal?
It depends on three things: the unit's rated capacity, the temperature and humidity of the air entering it, and how many hours it actually runs.
The table shows how much water vapor the air carries at common room conditions, compared with the 30 °C/80 % RH rating condition. The values are humidity ratios calculated at standard sea-level pressure. They describe the moisture available to the machine, which is why collection falls so quickly in cool rooms.
| Room air entering the dehumidifier | Water vapor in the air (g per kg of dry air) | Compared with 30 °C/80 % RH |
|---|---|---|
| 30 °C / 80 % RH (industrial rating condition) | about 21.6 | 100 % |
| 25 °C / 70 % RH | about 14.0 | about 65 % |
| 20 °C / 60 % RH | about 8.7 | about 40 % |
| 15 °C / 70 % RH | about 7.4 | about 34 % |
| 10 °C / 80 % RH | about 6.1 | about 28 % |
A machine does not remove all of that moisture, and its coil performance also changes with temperature, so treat the table as a guide to direction and scale. For an exact figure, ask the manufacturer for the capacity at your room condition.
What does the rating on the label mean?
The rating is the water removed in 24 hours of continuous running at a fixed test condition. Different markets use different conditions, which is why the same machine can show different numbers:
| Rating condition | Where it is used |
|---|---|
| 30 °C / 80 % RH | Common for industrial and commercial units, including all Yakeclimate refrigerant models |
| 26.7 °C (80 °F) / 60 % RH | Older US test procedure for portable units |
| 18.3 °C (65 °F) / 60 % RH | Current US DOE test procedure for portable units |
The US switched portable dehumidifiers to the cooler 65 °F test, so the pint ratings printed on US units became smaller for the same machines (ENERGY STAR). A unit rated at 30 °C/80 % RH will show a much higher number than the same unit tested at 65 °F/60 % RH. Compare models only at the same condition.
Converting units: 1 litre = 2.113 US pints. A rating of 90 L/day equals about 190 pints/day at the same condition.
Why does a dehumidifier collect less water than its rating?
Five reasons, all normal:
- The room is cooler or drier than the test condition. Less moisture in the air means less condensate (see the table above).
- The unit cycles. Once the room reaches the humidity setpoint, the compressor stops until humidity rises again. A unit that runs 10 hours a day collects roughly 10/24 of its full-run output.
- Pull-down is over. A damp room full of wet materials gives up a lot of water in the first days. Collection drops as the room and its contents dry out.
- Defrost. Below about 18 °C, ice can form on the coil, and the unit stops dehumidifying while it defrosts. Low-temperature models defrost less often.
- Poor air circulation. The machine only dries the air that reaches it. A unit in a corner of a large hall can show its setpoint while the far end stays damp.
When does low output mean a fault?
Compare today's collection with earlier days at a similar room temperature and humidity. A sudden drop at the same conditions usually has one of these causes:
| Symptom | Likely cause | What to do |
|---|---|---|
| Air from the outlet is not warmer than room air | Compressor not running, or low refrigerant | Call service |
| Ice on the coil | Room too cold for the model, or low airflow | Check the filter; consider a low-temperature or desiccant unit |
| Weak airflow | Dirty filter or blocked coil | Clean the filter and coil |
| Unit runs but tank stays dry | Drain hose disconnected, or water leaking inside | Check the drain path |
| Unit stops often | Tank full or float switch stuck | Empty the tank or fit continuous drainage |
If the room humidity is already at the setpoint and the unit is cycling, low collection simply means the space is dry.
Rated daily removal of Yakeclimate dehumidifiers
All our refrigerant models are rated at 30 °C/80 % RH, measured in our enthalpy-difference laboratory.
| Range | Model examples | Rated removal | US pints/day (same condition) |
|---|---|---|---|
| Portable (RYCM) | RYCM-60C, 90C, 138C | 60, 90, 138 L/day | 127, 190, 292 |
| Floor-standing (RYCF) | RYCF-10S to RYCF-40S | 240–960 L/day | 507–2,028 |
| Ceiling-mounted (RYDZ) | RYDZ-26DM to RYDZ-40S | 26–960 L/day | 55–2,028 |
Related: portable (RYCM), floor-standing (RYCF), ceiling-mounted (RYDZ).
For a project, send us the room size, the temperature and humidity you expect, and the moisture sources. We will give you the expected removal at your conditions, not just the rating.
Tank or continuous drainage?
At industrial capacities, use a drain. A unit collecting 90 litres a day would fill a 10-litre tank about nine times. Choose a model with a continuous drain connection, run the hose downhill to a floor drain, and add a condensate pump where there is none.
FAQ
Frequently asked questions
How much water should a dehumidifier collect in 24 hours?
At its rating condition, the rated amount. In a typical room at 20 °C/60 % RH, much less, often less than half, because the air holds far less moisture and the unit cycles once the room is dry enough.
Is it normal for a dehumidifier to fill up fast at first and then slow down?
Yes. The first days remove water stored in the air, walls, floors and stock. Once that is gone, collection settles to the rate at which new moisture enters the space.
Why does my dehumidifier collect less water in winter?
Cold air holds less water, and coils can ice below about 18 °C. Use a model rated for low temperatures, or a desiccant dehumidifier for cold spaces.
Does a bigger tank mean a bigger dehumidifier?
No. Tank size only sets how often you empty it. Daily capacity is the rated L/day or pints/day.
How do I estimate how much water my space produces?
Add up the moisture sources: people, plants, open water, wet products, and outdoor air entering through doors and ventilation. Our dehumidifier sizing guide walks through the calculation.
References
- ENERGY STAR, Dehumidifiers: product guidance and capacity ratings.
- US Department of Energy, Uniform test method for dehumidifiers (10 CFR 430, Subpart B, Appendix X1).
- ASHRAE Handbook—Fundamentals, Psychrometrics (humidity ratio calculations).
