I have this in my 280 SQ ft RV. Now to be fair, I am close to Houston, Tx, which is at the moment, 100% humidity outside. However, with the dehumidifier AND my 13,500 BTU RV a/c running, I can temporarily get the inside down to 55% humidity. When the RV a/c shuts off, the humidity immediately starts to climb with just the dehumidifier running. Like it will quickly get up to 69% humidity with the a/c only shutting off for like 20 minutes between cycles. Now I know that RVs are sealed up as tight as a home, so it's to be expected to a degree, but this dehumidifier is supposed to be rated for an area almost 10 times the size of my RV. The only way I can see that being realistic is if this dehumidifier was in a very new, 100% sealed, energy star home with zero leaks. I personally would not use this dehumidifier for an area larger than 500 SQ ft max. If it is very humid in this location, like 100% humidity outside, I think I would limit it's size to a 250 SQ ft room. Also in this environment in my RV, the tank fills up in about 8 hours and then it shuts off. So I have to empty it about 3 times a day.