How do I measure this dehumidifier as 50 Pints or70 Pints?
The 70 pint isnt a measure of how much the unit will hold. It is a measure of how much water the unit will produce in 24 hours. If you are using a hose drain there is no tank to worry about and the 70 pint unit just works faster.
What exactly do the 4 modes do? Whats the difference between them?
FAN: Circulates indoor air. In High & Low mode, the humidity can be selected between RH40%-80% and (continuous dehumidification).
Why does the dehumidifier sometimes blow out hot air?
Because the evaporator is working, the moisture in the air condenses into water and flows into the water tank. After passing through the radiator, it becomes dry air.