Changing from tank to tankless should not be particularly expensive if
the two heaters are the same fuel type. If you have an electric tank
type and install an electric tankless or have a gas tank type and
install a gas tankless.


WRONG!

Both the gas or electric tankless consume many times the fuel gas or
electric used by a tank type while they are operating.

figure a upgrade to 200 amps just for a electric tankless, plus a
second main for regular home power uses...