I have an Ecotec Pro 28 combi with no storage tank. I would like to have a storage tank and immersion heater installed so I can make better use of my solar PV. I am happy to have electric-only water heating so the hot water function of the boiler is no longer needed (although it might be good to keep it available for emergencies). Would it be enough to fit an isolator in the cold water inlet between the fill loop and the boiler? The system needs to be fully regs compliant.