Actually moving this 6 gallon from our old home that we demoed.
This will have a high temperature fin tube zone 150F or so at design, spare zone for indirect. Lochinvar Nobel running ODR, the radiant in slab zones will modulate proportionally with a manual 3 way mix valve. First time trying a 2 temperature system with a manual valve.
Boiler sensor in the tank well.
6 gallon in the tank, 1.4 in the Nobel, misc piping = @9
A 4500 W element gives me 15,000 BTU/hr for LP back up.
1-1/4x 1 tee with a 3/4 mipX 1" copper adapter increases the 3/4 side ports to 1-1/4" easily.