been wondering what's more efficient, using the hot water your tankless water heater provides, or heating the same amount of water to the same temperature using a kettle (both being electric)
@star it's still not 100% efficient, you still lose some energy. there's some distance between the water heater and the tap so some of the hot water stays in the pipes and cools down again. a kettle heats its components along with the water. both heat the wiring to the heating element since that's generally copper. there's some loss due to the resistance of the wiring itself of course, which is dependent on current, and my water heater with its three-phase 400 V supply can output more energy with the same current than my 230 V kettle.