Radiator control device, 8 letters
Radiator part, 8 letters
Blowhole, 7 letters
Circulatory conduit, 7 letters
Circulatory opening in a building, 7 letters
Heat conduit, 7 letters
Outlet, 7 letters
Ducts, 8 letters
Flues, 8 letters
Holes in space?, 8 letters
Insect's trachea, e.g., 9 letters