My new sump pump is pre-plumbed with 1.5" PVC, but my existing discharge line is 2". Is there any problem with connecting the 1.5" pump outlet to the 2" discharge line using a flexible Fernco coupling on the vertical section of the line? The check valve will be below the Fernco connection point, right at the base of the pump.
Update: I installed the new sump pump with the flexible 1.5" to 2" fernco coupling, and it's working like a charm. Thanks for the answers.