Abstract: The housing of a foundation ventilator has the usual front screen to protect the louvres within the housing, but the screen is part of a support frame used to mount the ventilator in an opening in a foundation wall. The support frame is frictionally retained in the opening by threaded bolts which can be easily loosened to gain access to the interior of the housing for cleaning or repair. It is not necessary to remove the ventilator from the wall. Similarly, if the support frame is damaged, it can be replaced without the expense of replacing the entire ventilator. The support frame has a connecting flange which seats within an extension of the housing to prevent relative lateral movement. Interlocking tabs and detents releasably attach the housing to the support frame with the screen in the support frame covering the front of the housing.

Abstract: A temperature actuated foundation ventilator comprises a rectangular housing with top, bottom and side walls, air permeable screens on the front and rear walls, a plurality of louvers extending between the side walls and a bi-metallic element for actuating the louvers into closed position in cold weather and into open position in hot weather. The bi-metallic element is exposed to the ambient temperature exteriorly of the housing and at the same time enclosed within a protective cover which includes means for positively supporting the bi-metallic element in operative position. Movement of the bi-metallic element responsive to changes in temperature causes corresponding movement of a control link connected to the bi-metallic element exteriorly of the housing and extending into the housing and into pivotal engagement with each of a plurality of louvers journaled in opposed side walls of the housing.