Hard water & Indirect Water Heaters

Dear Readers,
My house has hard water. My hot water pressure if very low due to, I assume, the scaling in the tankless coil hot water maker in my boiler which is original to the houe (1959). I plan on upgrading to an indirect water heater. Should I choose an indirect water heat that is a tank-in-tank model, or a coil model? Does either type make a real difference in avoiding hard water scaling within the tank and the reduced efficiency it causes?
Any advice appreciated! -Anthony Falcone
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.