Exact numbers at 13:00 are 39C/33C/6C. Heat pump and emitter output both at 4400W.
Mean radiator temp assumed to be 36C, room temperature closer to 20C.
All radiators, running at ((36-20)/50)^1.3 = 22.7%.
Estimated total rating 4.4 / 0.227 = 19.4 kW, which is consistent with previous estimates.
(this includes an additional 1 kW contributed by fans fitted to a few rads)
Related topic: Infer radiator spec and system volume using the MyHeatpump app