That crappy dehumidifier collects 600ml of water. That’s nothing. It won’t be anywhere near good enough for his damp bedsit.
I have a 10 litre one which cost me £200, it’s brilliant, I can put a full 8kg load of clothes out in one of my 4 double bedrooms (smell that wealth) and shut the door, 4 hours later the washing is dry and there’s about 5 litres of water in the tank. That tiny little thing won’t do anything.
ALSO! plasterers and decorators use bloody great industrial dehumidifiers usually spattered with plaster, paint etc. not crappy little Groupon specials. They’d get laughed off the site if they minced in carrying that little thing.