I wouldn’t consider on-demand heaters to be all that modern. Places that use on-demand water heaters are now at a disadvantage because it is much more challengi

I wouldn’t consider on-demand heaters to be all that modern. Places that use on-demand water heaters are now at a disadvantage because it is much more challenging to switch away from fossil fuels over to electric. Tanks, especially with a heat pump, can provide all the heating a household needs through a standard 120V15A socket. For on demand electric water heating you’re looking at upgrading main panels to supply an additional 240V20A and even that will struggle to heat the water enough in some winter climates.