Thermostatic vent control

Automatic thermostatically controlled damper means for a vent pipe comprising in combination, a flap plate substantially the same diameter as that of said pipe rotatable in said pipe about a pivot axis perpendicular to the axis of said pipe, a thermostat control device with a member movable above a predetermined temperature in an axial direction, mounting means positioning said control device inside said vent pipe to cause movement in the axial direction of said thermostat member to rotate said flap plate about said axis from a position substantially closing said pipe in a plane substantially perpendicular to the pipe axis to a position approaching a plane passed through the axis of the pipe, and structure in said mounting means holding the axial direction of movement of said control device disposed at a fixed acute angle with a plane passed through said pivot axis and including a lever member disposed to contact the thermostat movable member and said flap plate, wherein said actue angle is at an angle to a diametric line in said pipe formed by the pivot axis of said flap plate.