Most likely your water heater is an Atwood or a Suburban, so look at the ID tag for a model number of the heater itself -- then find a manual on-line. Some of these heaters have switches and valves right on the unit that you need to confirm are in the right position. Posting a picture here will help us help you...
2007 Tour Master T40C
Acura MDX toad
"It takes a great deal of time to recover from any improvement..."