OK, I think the R8845U is wired correctly, but I am not sure.
There is a black "hot" wire into the box, connected to L1.
A black wire goes from L1 to COM.
A black wire goes from NO out of the box to the circulator.
A white wire goes into the box, to a wire nut.
2 white wires come out of the wire nut, 1 goes to L2, the other goes out the box to the circulator.
A red wire goes to X1.
A blue wire goes to X2.
A red thermostat wire goes to R.
A white thermostat wire goes to W.
Nothing is connected to B or C.

If I were going to change the circulator, could I close the valve that sits just above it, and partially drain the boiler, or do I have to drain the whole thing?