Foundation ventilator

摘要

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.