Plugging the inlet makes it a closed loop system - the pump just continuously circulates air through the engine and media.
Otherwise you?ll pull ambient air in, making it much less efficient in terms of circulating, and adding humidity from the hangar.
This model pump has the intake on the bottom.
I used it for 23 months before the beads turned pink ... and it?s pretty humid here in Indy.
KUMP - Indianapolis, IN / KAEJ - Buena Vista, CO
RV-10 N410TS bought / flying
RV-8 wings / fuse in progress ... still
1948 Cessna 170 N3949V