2017 neuvo waterheater

i have only recently been using my heating on gas i have noticed water also heats when water heating is switched off is this normal
                                                                                              scotty

In a word yes, heats by transfer.

It got me the first time too! 
Now, if I’m putting the heating on I generally don’t bother with the water setting.

When the inside of the van reaches the temperature set on the thermostat, the heating will cut out and the hot water tank will start to cool down.  So if during the day the sun comes out and warms up the van, the water may not be hot.