external or water pump

on our neuvo when filling up with fresh water with the whale direct from a tap ...... we have a choice of selecting either water fill pump (only comes on for a minute as per the manual) or the external pump.  The manual is not clear and  it says don`t switch pump on if no water in system ...... so presumably we use water fill pump and when that goes off we select external.  Any ideas.

You don't say the vintage of your Nuevo or the type of control panel. If you have an EC328 or EC325 then you don't have to select any water pump setting to fill from the tap - simply switch on the panel as you would to get the internal lights to work.
For water pump you gave a choice of 3 settings, Internal, External or Both.  I leave mine set to Both and then, when I want to fill using the external pump it starts running as soon as I plug the Whale box onto the side of the van. Then, when the can is empty I leave the pump in the can and unplug the pump taking both to the tap for the refill. As soon as I replug the fitting to the sid eof the van it starts pumping again.  Offhand, I cannot remember if I have to have the pump switch on the EC328 switched on or not.  Whether filing from a tap or using the extra pump and a can or bucket the EC328 MUST be switched on - otherwise the solenoid valve will not open and no water will get into the tank.  I guess that the EC500 display control panel fitted to more modern vans works in the same way - but the manual will tell you.
There are lots of posts on the subject of the Whale filler which is like Marmite - folks either like it or hate it. Just search for "Whale filler" to read the comments.

Hey - that's my 1000th post - do I get a prize?

inspiredron wrote:Hey - that's my 1000th post - do I get a prize?

Nah, missed it, 1002 now......