Looking at the graphs, you seem to have some single data points for COP that are way out of range, hence the graph is basically flat, hiding the detail. These are surely anomalies and are maybe artefacts of the way the data is stored and processed? They only seem to occur when the pump is turning on or off.
@Bramco Hopefully the topic above will explain why it’s behaving that way and that it’s A Good Thing ™ 