The diagram at 6:18/9:19 appears to be incorrect. Measurement A should be the length of the riser pipe. The picture shows the extra 6.5 inches at the end of the measuring device plus measurement A. The seam should be lined up with the "notch" in the measuring device, not the entire length of the measuring device.
The diagram at 6:18/9:19 appears to be incorrect. Measurement A should be the length of the riser pipe. The picture shows the extra 6.5 inches at the end of the measuring device plus measurement A. The seam should be lined up with the "notch" in the measuring device, not the entire length of the measuring device.