Posted 1/12/2021 21:40 (#8746680 - in reply to #8746628) Subject: RE: Whole house tankless water heaters
you can buy a tank type high efficiency power vent gas water heater, even condensing. That's what I'd do before a tankless with hard water. Take a look at the procedure for acid flushing tankless, then decide.
If you think gas is going to stay cheap, a power vent standard efficiency would probably be worth it. If you think gas will go higher soon, then look at a heat pump electric in front of your existing water heater for more capacity.