Same flowrate as with HW+CH, 0.8m3/hr, 13.33LPM, dT, 10C, blr output, 13.33*60*10/860, 9.3kw, just enough to keep the boiler constantly firing, will probably change depending on the cylinder temperature.
I don't think you can do much more now, bearing in mind the thread title was about ignition lockout which has gone away.