Hi and Merry Christmas. This is very vague without much info as to what rig you have, what hot water heater you have, without pictures or much of a description, but here goes...
Generally, for a 6 or 10 gallon propane or propane/electric hot water heater: a cold fresh line will come in from the water pump/city water hookup, run to the inlet of the bypass valve, often a t-shaped 3-connection valve. In the "normal" flow position, water would then go from the #1 outlet pipe from the bypass valve to the low inlet of the hot water heater. Water would then fill and be heated inside of the tank. The upper outlet of the hot water heater would connect to a hot water line. This hot water line should have a backflow prevention inline valve connected to it after the tank, then the hot water line will continue to go provide hot water to the coach.
Outlet #2 from the bypass valve would have a pipe that feeds back into the hot water line going to the rest of the coach after the hot water heater and backflow valve. The backflow valve will prevent water from backing into the hot water tank. This is so you can bypass the hot water tank for winterizing, repairs, etc. This is probably the "interlooping" you refer to.
Hopefully, this makes sense to you. Good luck!
2005 22' BT Cruiser 5211, Chevrolet 3500 chassis w/6.0L Vortec V-8; 6'x12' Cargo Trailer; Honda CB500X motorcycle for street and ADV riding; Yamaha TW200 motorcycle for dual-sport and trail riding...All of it for fun and adventure!