Should the spring side of the Engel shaft seals be facing the water or the inside of the WTC? I think the Engel instructions recommend mounting the seals so that the spring faces the water, as water pressure will press on the lip, making the seal tighter. However, I've also seen people mounting the seal the other way around, so that when the WTC is pressurized (either by a piston tank or rubber bladder filling up), the air pressure inside the WTC will make the lip tighter around the shaft. I guess a similar thing could be argued for oil seals which do not have a spring. In which case, which direction should the conical lip be facing?
So what is the definitive answer on this?