Hello

I don't understand all the functionalities of my boiler. It is 25Kw with five elements each is 5Kw. Each element has a breaker and there is one more breaker called 'Aquastat'. I don't understand the functionality of this breaker! Why it is there and when do i have to turn it on?

My boiler is Make: 'Franks Piping co. Ltd." Model: 'E-CE'. However, since this company doesn't exist anymore, I don't know who would help me on this.

thanks for all of your help

Sam