After installing a traditional vent in the bathroom ceiling for venting I decided I did not like the look. All this custom wood work did not need to be distracted by a rectangle in the ceiling.
Now the bathroom is vented by pulling air through holes in the shower curtain rod. This allowed be to avoid making more holes in the walls/ceiling.
Fresh air can be pulled into the house by opening a gate valve located in the upper storage area. (Like the one under the sink but smaller.). When open air can be drawn from under the house through 2″ tubing and through a filter. There is an outlet vent as well in case windows have not been opened. (In the cabinet near the outside door with the battery.)
The main intake vent (the owl) is located near the floor and door where the air should be the coldest in heating weather. The copper pipes on the ceiling and in the loft are also intakes but move a smaller volume of air.
The outlets are near the ceiling behind the roosters.
The Roosters (and owl) were cast-iron trivets designed for hot pans to sit upon. It took a while by I was able to grind the feet off then drill screw holes (see the eye?) so they could be fastened flush to the walls.