Urgent! I need a shower!

Ours is the earlier version of the Alde, just black and white . On that when the gas symbol is highlighted it tells you if it is off or on.

However, this means nothing if it is turned off at the isolation tap. We have several in our van for the various gas appliances. Have you checked to see if the Alde one is on.

Thanks for your reply SteveL.

By sheer fluke, we have success. There is a symbol that was a blue shower symbol with a cross through it. By pressing it and changing that to a green shower symbol with a cross through it, we have hot water. 

I don't pretend to understand this. Just glad to have hot water! 

The symbol described switches of the hot water as you found out switches off the hot water. If you are on gas then it saves some.   If it helps we have got Alde set up as follows.  Priority power source set to prioritise electricity over gas and it set up so the overnight setting is used with the water heating set to off.  So even like know when we don't have ehu it will look for electric but as there isn't any uses the gas.  Also there in the settings there is a symbol like a wedge this will boost the hot water, which is handy if a couple of you want a shower.