My hopper gets condensation sometimes as well. I soak it up with a paper towel. Other than somehow drying out the coal, there is not much you can do. The DVC is a direct vent stove & is a closed system. There is a pressure sensor which checks to make sure the stove burn chamber is running at a negative pressure. (The stove controller runs the exhaust blower a bit stronger than the combustion blower - there is no draft, the stove creates the burn environment & the venting) Leaving the hopper lid open or putting holes into it would cause the stove safety to trip. The hopper lid is essentially at the top of a sealed container, putting cold, damp coal into it then heating it up will cause condensation. This is my second season like this - no rust in the hopper, most of it is SS.
It would be interesting to see what Harman thinks about the condensation, because they warn you not to put wet coal into the stove....
Yes, that's what we've been doing -- just opening the lid every once in a while to check, and drying it off if it's there. OK, I'm relieved to know we're not the only DVC-500 owners who see this.
I guess it's like putting a Rubbermaid container in the microwave without popping the top, and reheating something. But popping the top on the hopper is a no-no, so if the coal's damp then condensation can happen.
OK - thanks for your help!!!