If you don't have any hot water in your vehicle, here are a few things to check:
- The water heater will not work if there is no gas, no water or if combustion gases are able to enter the motorhome. The red light indicates a fault.
- Check on the panel that the fresh water supply is not empty.
- Check that the gas bottle is not empty or closed: by switching on the gas cooker, by weighing the gas bottle.
- Turn the water heater off and on again.
- If you have no hot water in a Mac Louis camper van or a Chausson/Challenger van: check whether a window (bedroom/kitchen) is directly above the flue gas outlet, in which case it is fitted with a safety switch. The water heater will not work if the window is open. You can put a wedge between the contactor and the window so that the contactor fits into the box.
Finally, if, despite all these operations, you still have no hot water, it may be that the Truma chimney cover has not been removed. You need to remove it (by pressing on the top of the cover and tilting the bottom of the cover upwards), as it prevents the burnt gases from escaping, so for safety's sake, the water heater will not start up if the cover is present.
For more details, see this blog post.