Using the whale system to fill the water tank

If you remove the brown plastic ventilation grill underneath the o/s seat in front of the EC700 you will just be able to access the back of the Whale filler socket and a separate solenoid operated water valve just beneath it.  If you remove the latter you will find a small piece of gauze on the inlet side.  This is needed to keep grit out of the valve.  It is likely that this gauze needs to be cleaned.

Paul beat me to it by seconds

Just to add to what Paul has said, the Whale system has two pressure switches.  One is ahead of the non return valve (NRV) that is ahead of the submersible pump that's inside the fresh water tank.  The pressure switch and NRV are one unit.  The second pressure switch is inside the Whale inlet socket.  When water pressure is applied to the outside of the inlet socket, the switch closes a circuit with the solenoid which opens the valve allowing water to flow into the fresh water tank.  When the tank is full a float switch at the top of the fresh water tank cuts the power to the Whale inlet socket and its pressure switch and therefore to the solenoid which causes the valve to shut.

It is a little tricky to get at.  There is better access by removing the top of the EC700 but that’s more scary.  I replaced the solenoid valve with a short section of pipe to remove a point of failure.  It means the tank can be filled with a hose through the whale inlet socket without 12v and it does so until the tank overflows.  The water roll method of filling is unchanged and will still cut off when the tank is full.  I didn’t push one of the quick fit connectors home fully so had a little leak.  Worth checking that yours doesn’t leak.

You need one of these:

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It plugs into the Whale inlet socket and gets its power from the two brass contacts in the socket.

If the water fill system is working properly, the pump will turn off as soon as the fresh water tank is full but not as Quilter points out when the aqua roll is empty.  It's not a good idea to leave the pump connected when the fresh water tank is full because it will start running again as soon as you draw water.  This may then result in the aqua roll emptying leaving the pump still running which will damage it.

BigBertha wrote:So there are two scenarios here. Aqua roll empties before onboard tank is full - in which case I monitor the Aquaroll and stop the external pump before it tries to suck too much air. If the onboard tank reaches full before the Aquaroll empties…does the power to the external pump get cut automatically?
I’ll look forward to buying and having a play.

Yes - the power to the Whale inlet socket is cut as soon as the fresh water tank is full.  This has two effects:  

One - the power to the solenoid water valve beneath the Whale inlet socket is cut causing the valve to shut thereby stopping any further flow of water into the fresh water tank.  This is needed when the Whale inlet socket is connected to a mains water supply.

Two - the power to the brass contacts on the outside of the Whale inlet socket is cut which stops the external pump motor from running.  This is just as well or else the motor would be trying to pump water through a closed solenoid valve which would cause the motor to burn out just as it burns out if it is left pumping air.