Abstract: A damper assembly for conserving fuel consumption in a heating furnace comprises baffle means pivotally mounted in support means arranged to fit in an outlet flue communicating between the furnace and a chimney stack so that the baffle means is movable between a fully open position whereby the flow of combustion gases from the furnace to the stack is substantially unimpeded and a fully closed position providing a restricted flow path for the gases whereby the gas flow to the stack is reduced. Associated wth the baffle means is thermostatic control means responsive to the temperature of the combustion gases for moving the baffle means to the fully open position at a relatively low temperature indicating that the furnace is inoperative and for moving the baffle means to the fully closed position at a relatively high temperature indicating that the furnace is operative.