safe all 420, i have just put a 5 inch inlet ruck into me room from outside ,but is it best to draw air in from a certain end of the building were its sunny all day south east facing? ,and ive put the outlet to kick out west ,as ive read suming about useing a compass to get the max sunlight were you draw air in ,so its warmer and not as damp? and its very cold now so il prob bring in from outside in summer and from inside in winter?