# Dehumidifier produces 100 g of water every day. No effect on relative humidity

First, my calculations. Let's assume a sealed 5x3x2 meters room and ambient temperature of 20 C. Volume is 30 cubic meters. According to this table, at 100% relative humidity there would be 17 g of water vapor per cubic meter or 510 g in the whole room. Henceforth a 10% drop in relative humidity should require about 50 g of water to be removed from the air.

The problem is that I'm getting about 100 g of water from my dehumidifier every day and (according to the psychrometer I have) the room is still at 70-80% relative humidity like it was before I installed the dehumidifier. Psychrometer works well outdoors and there's no reason to suspect it. The room has no sources of water vapor, save for myself and a cup of cold water. The door is closed most of the time.

Am I wrong at math? Missing some other important aspect? Any ideas how to help the situation in general?

• What are the walls made out of? What is the floor and ceiling material? Are any made of materials that can absorb water (concrete, wood, etc)? A lot of materials will absorb and emit water vapor to reach an equilibrium depending on RH. A room that has been saturated will take a long time to de-saturate. Commented Dec 30, 2020 at 18:50
• It's a fairly regular apartment in a concrete building, with wallpaper on the walls and a woodblock floor. Intuitively, it should not be able to absorb or release too much moisture - I would be getting mold all over the walls, not just on windowsills. Commented Dec 30, 2020 at 18:59
• Short form: there is a source of water... Commented Dec 30, 2020 at 18:59
• Not an expert but psychrometers indoors need to be located where the recorded temp is not significantly affected by varying conditions (heat/cooling vents, etc) and should reflect the ambient temp in the room. Not sure if this helps but.... Commented Dec 30, 2020 at 19:02
• Yup, it's because "The dehumidifier is actually a cheap desiccant-based thing". Life is tough. It's tougher when you're cheap. You just burned that money away, like setting paper notes on fire. How can you afford to burn money? And yeah, 10 litres is realistic. My dehumidifier holds about 8l and I can empty it 3 times a day when it's really going. Commented Dec 30, 2020 at 20:26