Return vent below shower - hot air

wborst wrote:
On our Newmar Mountain Aire, that vent allows warm air into the wet bay to prevent freezing. In the wet bay is a switch marked HEAT. When this switch is on, and the outside temperature falls below 40* and the furnace is enabled, a fan comes on that pulls warm air through this vent into the wet bay.

Our Mountain Aire is the same except when you turn on the switch the fan in the basement suck air from a front floor heater vent and the vent under the shower warm air comes out to do as you said , keep things from freezing in the basement. If you turn that switch on in the summer then you can suck cold air out of the coach and cool down the basement and the warm/cool air will come out of that vent under the shower.