Hot Water Confusion!!

I have a Central Heating system using a Glow Worm Spacesaver 45/60 boiler.
Central Heating and heating of water works fineand its only during the summer months that I've noticed an oddity with it.

Both the Heating and Water heating on the timer have been switched to the off position for last couple of months and yet I continue to get loads of hot water. If I empty the tank until it runs cold its back to being hot again within a couple of hours.
The bolier doesn't appear to be heating this water as only the pilot light is on. ( If I turn water heating on at the switch I can see it go from pilot to heating and back to pilot if I turn water heating off -so that side of things is ok).
My only conclusion is that the water is being heated by an immersion element somewhere?? Please excuse my ignorance in all matters heating
Underneath the Water/Heating Timer ( Randall 4033 ) there is an 'old fashioned' electrical switch that is turned on .
Is it possible thats its an immersion heater switch?
I just don't know where all my hot water is coming from???
Help

Look at the hot water cylinder. The immersion heater is on top, to one side (probably). Follow the thick cable to the switch.

I emptied the tank until the water was running cold and then turned off the 'old fashioned' electrical switch. The water stayed cool - When turned on again the water heated up. So I have an immersion that I didn't know about or its an immersion bulit into the water tank??

I'll leave it switched off and just heat the water from the Central Heating bolier.

Still a bit bemused as to why I have an immersion and central heating??

feronni said:

Still a bit bemused as to why I have an immersion and central heating??

Click to expand...

It's normal. The immersion heater is a back up in case of boiler breakdown.