Welcome to the Suites ownership--
If yours is like my '05, there will be several valves--lots of plumbing--behind the driver-side sliding door. There is always a cold line in and a hot line out of the water heater, and valves in the lines to cut it out of the water system--also, a line between these 2 lines with a valve on it. If the in/out lines are open and the inbetween line is closed, you will get water into the heater. If the in/out line valves are closed and the inbetween line is open, the water heater is bypassed.
If you have the newer manifold-type plumbing, there should also be tagged lines that are labeled for you to figure out--same principle, cut water off to heater/open bypass for winterizing; open lines to heater and close bypass line to operate heater. There is logic to water flow--easy to figure out if you can see the lines.
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired