I get the concept of the three drains…
Primary with the T and 90 being submerged, secondary with a trickle and emergency above waterline…
First two go into sump below water line, emergency above to make noise…
But how/what does the 90/down pipe on the primary achieve when the other side of the T is open to water as well… I could see if it was two 90s but I don’t see how water would come from the Down pipe with the T open…
Primary with the T and 90 being submerged, secondary with a trickle and emergency above waterline…
First two go into sump below water line, emergency above to make noise…
But how/what does the 90/down pipe on the primary achieve when the other side of the T is open to water as well… I could see if it was two 90s but I don’t see how water would come from the Down pipe with the T open…