Anyone know if it's possible to change the electric water heater for one that will work on both gas and electric? (Or rather have it changed).

They exist, because we have one on our 2017 Triton. It sits next to the onboard water tank under the port-side bed. Don’t know what your configuration is. Very useful when off-grid.

We have a Troll 540. The electric water heater is sited under the long cushion below the window at the rear of the van. We managed very well off grid last summer but missed the hot water so a having the electric heater changed a dual system would be good.

Thank you. I'll ask him.

Our 540 has a Truma 10 litre gas/electric boiler mounted under the front seat next to the toilet. It is too big to fit in the space below the rear window so I guess some replumbing would have to be done. The Truma is expensive at the best part of £500 but I believe there are cheaper alternatives such as Propex. I would imagine that the cost of rerouting the pipes plus installing a gas line & drop-out vent, drain valves, etc will add considerably to the cost of a dual fuel boiler.

Also consider where the control switches go. Ours is the combined Truma unit under the bench seat. For some reason (probably because it was easiest), the switches are on the panel beneath the seat, just where you can knock them with your legs/feet and turn it on or off unintentionally.