As said above.........the switch with the red light is for use on Gas, light will come on until the burner fires up then go off, you do need the gas turned on.......if the gas is off it will stay red for a period of time then shut down for a bit then try again.
The switch on the outside of the HWS is the 240v switch but turn it on and leave on, turn your 240 on/off at the power point as the external switch can fail.
Always run water thru the HW line before turning the HWS on power or gas.
When using your water pump it will run until the line is pressurized or while a tap is turned on.
20- 25 mins to heat up.
If you haven't got a manual go here;
http://caravansplus.com.au/catalog/pdf.php?pdf_id=555 you may need to have a read of your fridge manual also as it may give you trouble also.
Don't be a stranger here, heaps of information and laughter on our site, there's never a stupid question either unlike some other places.........we even allow Wait Awhiles on here.