Per Marc:
My neighbor had a tankless installed a few years ago and was quite happy with it until one fateful morning...the ****ing thing quit in the middle of his morning
shower. There was no warning, the water temp dropped instantly from a nice warm shower temp to 52F, the temp of his well water.

Now that you have said it.... one of the things I like about our nat
gas-fired heater is that it is immune to power outages.
--
Pete Cresswell