Is it designed a bit like a condenser tumble dryer - produce a tank of hot water which has to be periodically emptied?
Let's say it has a 20L tank, that's about the maximum I think a healthy adult could lift out of the machine to empty it. 20L of water at, let's say, maximum safe contact temperature of 60C to avoid scalding, and starting off at the tap temperature of 20C (summer's day). So 40C rise of 20L of water - by my maths that's just around 0.93kWh.
Even a 5000BTU unit will move more heat than that in an hour... and that will just about be enough for a small box room.
So yeah, I must be missing something here.
Surely they can't just be dumping humid heat directly into the room... yes, that will cool down the surface of whatever the cold outlet is pointed at, but the room will still get warmer!