I have a client who is using a hot water tank and standard 14in immersion heater element on a 13A fused spur for their hot water needs. It's running 24/7 relying on the immersion stat. There is no gas to the property (and no potential of getting it). Its a very large 5 bed farmhouse. What's the best replacement for this? There has to be a more modern and efficient way of doing this? Anyone have any recommendations? It's a large property with several bathrooms a kitchen and a utility so I don't think individual instantaneous water heaters will do. Thanks for any advice.