Abstract: The molded plastic rectangular shutter support housing and the mounting cover frame of the two-piece foundation ventilator are provided with connector devices for removably maintaining the shutter support housing and the mounting cover frame in assembled condition and for permitting disassembly of the mounting cover frame and the shutter support housing, if desired. The connecting devices include integrally molded clip members on the mounting cover frame with inwardly extending locking portions positioned in overlying engagement with integrally molded flanges of the shutter support housing to permit the shutter support housing to be removed from the mounting cover frame by sliding the shutter support housing longitudinally in one direction along the mounting cover frame and for assembling the two parts together by longitudinally sliding the shutter support housing in the opposite direction along the mounting cover frame.

Abstract: The mounting frame of the ventilator is formed of molded plastic so that it contracts when the temperature is low and expands when the temperature is high. In order to accommodate such expansion and contraction, a screw is supported for longitudinal adjustment in one wall of the mounting frame so that the outer end firmly engages one side of the wall opening. A compression spring has its inner end fixed on the opposite wall of the mounting frame and its outer end engages the opposite side of the wall opening. In one disclosed embodiment, the compression spring is tapered with the smaller inner end being fixed to the mounting frame by a screw. In the other embodiment, the compression spring is of the same diameter throughout its length and the inner end is threaded with a threaded bore in the mounting frame.