Please critique my indirect layout/design

Hi. The tankless coil in my 23 year old Trianco boiler is having a hard time keeping up with even a single 2.5gpm shower head so I am planning to install an indirect water heater setup.

I took a shot at a layout on paper as a way of trying to understand what was needed. Below are two drawings. The first is my current tankless coil setup. The second is my best shot at what I'd need to do to convert to an indirect setup. I am hoping someone with expeience installing indirects might be willing to critique my design. In particular the components I am proposing and their location in the design.

Thanks in advance for any insights/edits/recommendations you can provide.


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