To some degree, a power saving feature for hot water cyclinders in NZ has been used since at least my grandparents time. https://www.eeca.govt.nz/assets/EECA-R

To some degree, a power saving feature for hot water cyclinders in NZ has been used since at least my grandparents time. https://www.eeca.govt.nz/assets/EECA-Resources/Research-papers-guides/Ripple-Control-of-Hot-Water-in-New-Zealand.pdf https://www.eeca.govt.nz/assets/EECA-Resources/Research-pape...