|
Bernie,
That truly is a return air vent for the furnace. There was a thread on this last week but now I can't find it either.
It's important to keep the furnace operating in a recirculation mode to be efficient, with similar volumes of air being returned to the furnace as is being discharged from the furnace. Blocking that vent will change that configuration into a one way air mover trying to move air from that little furnace space into a sealed living space with no means for relief air to get back to the furnace space. It will slow the airflow and most likely cause the furnace to overheat and shutdown.
|