Where did you have this Tee added? If in either the feed or return for the main engine fuel system then this is not the recommended procedure for a Sprinter.Also had them add an auxiliary tee for a future heater addition...
Spot on, they seem to know what they are doing if that's what they did!@Cheyenne
Keith, thank you for asking for clarification. I had them add the Tee on the existing KL1 line, just below (on the fuel tank side) of the factory espar pump. (similar to this one: https://sprinter-source.com/forums/index.php?threads/57915/post-625984)
I thought that was an acceptable procedure, happy to snap a photo for clarification if it seems questionable.