So have you started a system design plan yet and material takeoff. Now is the time, this way you won't be buying things last minute at higher prices possibly.
I'll be dropping a new 1" pex-al pex line in the ground, going to abandon the old line since I'll be parking the new furnace a little farther down. Going to keep the original w/a heat exchanger in the gas furnace as well as the w/a stand alone exchanger near the basement shower, gets damn cold in that NW corner.
Since money is going to be pretty tight this summer, like that's new, I won't be getting a w/w plate exchanger with mixing valve for the DHW, until next summer.
This summer, I'll dig down a few inches, lay some gravel & lay some 4" patio blocks of some sort from Menards, 4' x 8' area to set the furnace on.
While laying in the water lines, I'll drop in 10 awg underground electrical wire for a 60 A breaker box to my shed next to the furnace, just in case I need welding done in the far far future (15-20 years) on the burner.
oaky