Hot Water Tank Setup Advice

[Martin.R]

I need some advice on how our hot water is setup please, I am a total novice when it comes to this area of our house.
I have attached some pictures of our hot water tank and the switch boxes attached to it.
Could somebody please advise on how this setup works so I know what to look for if I get any problems.

The reason for this post is this morning we had no hot water but the heating was on, the hot water tank and pipes felt cold.
I turned on the switch on the wall next to the tank and it heated up and we had hot water again.
I am not sure if the wall switch is normally off or on, my daughter had been in the airing cupboard the night before and she has a tendency to switch every switch she finds thinking it is a light

Do we have an immersion heater? It looks like on the tank we either do or we have the fitting for an element.
It concerns me slightly because if we do have an immersion heater then the boiler must have a fault as we have to have the immersion on for any hot water (I think).
Certainly when it was switched off we had no hot water.

Regarding the silver box the switch is AUTO or MANUAL (Currently AUTO), I’m sure if some years ago we had an issue and a friend had a look and it was just the switch in the wrong position.

Many thanks in advance for any advice given.

 

[flameport]

Looks like a standard Y plan system. Cylinder is heated by the boiler, which also does the central heating.
The lever should be at Auto, where it is in the picture. Manual is just for filling/draining the system.
There is no immersion heater - a blanking plug has been fitted instead.
As for the white switch on the wall - could be for anything, or nothing at all. If the system only works with it on, then leave it on.
Hot water temperature is set by the small white thermostat on the side of the cylinder (held on with the yellow tape).
When it is on or not should be via a programmer or timer elsewhere.