Hi,
THe indoor coil has a drain line, and the evaporator gets down to about 40F, cooling the air, and also collecing moisture, much the same way a cold drink will be covered with moisture on a warm humid day. Even if the air is fairly dry, it can still produce a quart of water in a couple of hours.
I guess that this manufacture says it can tilt with the front up, but not front down. If you are really curious, then take off the outside cover, and inside cover, you might find the evaporator eventually, and find out that the evaporator drain tube is on the rearward right or left (or both sides) of the evaporator, with a small 3/8" tube going to the outside of the unit.
Fred.
