Safety stovepipe damper assembly

Claim 1

A thermally responsive safety stovepipe damper assembly adapted for mounting in a natural draft combustion unit flue, said damper assembly comprising a generally cylindrical duct for mounting in communication with said flue, said flue having a pair of diametrically opposed aperatures therein, a side plate including means affixing said side plate to said flue, said side plate having an aperature disposed in co-axial alignment with said flue aperatures, a slotted clip including means affixing said clip to said plate, a latch including means for pivotally mounting to said side plate, said side plate including stop means for said latch, said flue having a damper plate with a generally circular periphery of diameter somewhat less than the inside diameter of said flue, a damper shaft extending through said flue aperatures and said side plate aperature in rotational relation therein, said damper shaft including means engagable with said damper plate for non-rotatable relation therein, a yoke having a base with extending legs, said legs having aperatures therein in co-axial alignment, said damper shaft extending through said yoke leg aperatures, a bushing having a bore, said bushing affixed outboard of one said yoke leg in co-axail alignment with said aperature therein, said bushing receiving said damper shaft, means securing said bushing to said damper shaft in fixed relation thereto, said bushing diametrically opposite said side plate, said damper shaft having a handle at one end, a helical compression spring receiving said damper shaft and co-acting between said handle and said yoke leg, said spring means insuring said means engagable between said damper plate and said damper shaft, a pair of aperatures disposed at said yoke base in co-axial alignment parallel to the axis of said damper shaft, a shaft extending through said aperatures in rotational relation thereto, a knurled wheel affixed to one projecting end of said shaft, means engagable with said latch, a helically shaped bimetal strip in co-axial alignment with said shaft, said bimetal strip affixed at one end to said yoke base and at other end to said shaft, said bimetal strip being responsive to changes in temperature of said flue to rotate said wheel for disengagement of said latch, a bead chain pivotally secured at one end to said yoke leg, said chain engaged in said clip slot for predetermined travel limit of said yoke for closing of said damper plate, said yoke base having housing means to enclose said bimetal strip against said flue when said damper plate is in an open position, said flue having a heat shield including means affixing to said flue, said heat shield reducing thermal radiation from said flue to said bimetal strip when said damper plate is in a closed position.