UA 3902 then UA 1229 at Houston
Toronto → Houston → San Francisco
Timetable, Houston time
08:27UA 3902 from Toronto at the gate
07:40UA 1229 to San Francisco leaves the gate
23 h 13 apart on the timetable, overnight
UA 1229 leaves 23 h 13 after UA 3902 arrives on the timetable: more than half a day, so not a connection we count.