I want to install a whirlybird that will extract humidity from a bathroom in summer, but be able to be changed to extract from above the ceiling in winter. Thus keeping house ventilated in summer & reducing humidity in bathroom, and not cooling the house in winter. I envisage a whirlybird ducted to the bathroom, with the ducting having Y or T piece with a flap. Thus the flap could direct the whirly's suction to either the bathroom or ceiling space. Can you get ducting with flaps in it? And if so how would you control the flap from the bathroom? Would appreciate any thoughts on this issue.