I just moved into a flat. At old address, gas boiler was used. Now, everything in the flat uses electricity. I'm new to electric water heater and do not really understand how it works. I find out that the electric water heater is powered on 24/7. Can I turn off the heater when I do not use it, and switch it on when I'm about to use it, e.g. shower?
There are two wall mounted convector panel heaters in the flat. Thus, I think the water heater only provides hot supply for shower and taps.
The model of water heater in my flat is "OSO 20 RD125 (DIRECT model)".
The specifications of the water heater is:
There are several AC main power switches around the heater:
There is one switch labelled as "Isolator". I'm not sure if it is for the heater. If it's, please advise its function in the heating system.
Close-up view of switches. There are four red leds on the TIMER panel, and all of them are ON. What does it mean?
The hot water output pipe is insulated.
 Should I turn it off if I use the water heater model as described above?
 Should I turn both (4) and (5) switches off, or only either of them?
 What is the function of the ISOLATOR?
 Any idea how does the timer work?
 Is it safe to switch it off during winter? Will this cause damage to the water pipe?