My current coach, prior coach and before that travel trailer all have/had propane water heaters. In each RV, the "plumbing" at the water heater had heater isolation and by-pass valves. If your coach has a propane water heater with tank, it should have a by-pass located very near the tank.
This is an image of the typically plumbing, including by-pass valve, for a propane water heater. Hope this info helps!
Mike & Cindy in Katy, TX
2016 Newmar Ventana LE 4037
2016 Jeep Wrangler Unlimited Sahara