2008 Fourwinds Citation 29G

Good! Now, NEVER forget and light it on LPG or turn it on 120VAC with no water in the tank!!! Enjoy.

Found it. It is under the cabinet above the sink!

It'll depend on the water heater itself and how the builder installed it. Say it has electronic ignition. There'll be a switch inside, on a panel, maybe the range hood. They usually have a status light that goes out once the burner lights satisfactorily. Then if it also has an electric element, there may be a second switch inside, a switch outside on the unit itself, or both.
We have a Suburban SW6DE. SW = Suburban Water Heater, 6 = six gallon, D = Direct Spark (electronic) Ignition, E = 120 VAC element. There's a 120-VAC switch built into the heater, and there's another one near the switch for the electronic.

There must be a water heater switch, or even 2 of them, one for propane and one for electric if so equipped. May be in a panel with switches for other things. I don't have the 29G so I am not much help. Mine has the switch on the kitchen console.

Enjoy your 29G.