Hi! I own a 2017 Thor Chateau 28z. There is a t-handle on the passenger side just aft of the entry door. I purchased the coach from a private individual and was told that handle has to be pulled to dump the lav. I have searched the manuals but cannot find it or a description. I would like to know what exactly that handle does. Any input greatly appreciated. Thank you.
Welcome to the forum!
Your Black tank is on the passenger side of the coach. That T-handle shuts off the flow of "black" before it crosses under the coach, and gets to the actual dumping valves.
Leave it closed until you're ready to start "abandoning ship".