The charts for this system match those from many others we’ve seen here with trapped air; it seems to be a common problem. The kamstrup in particular will report zero flow and an error code instead of a partial reading.
TrystanLea:
This is a known issue. Ultrasonic heat meters are very sensitive to air in the system and will not report a heat value if air is interfering with the reading. Your heat pump will be producing heat, this is just a heat meter issue!
It would be worth making sure that your system pressure is above 1.5 bar and to go around the radiators bleeding any air that may be present. Do you also have a bleed valve on the hot water cylinder coil?
See this topic in particular:
Glyn and I have been going through the data here from the system we have access to to try and work out how prevalent this issue is. It does seem that it’s affecting a larger number of kamstrup units than we thought.
50% of kamstrup systems are not showing the issue, 22% of systems did show the issue early on but the issue has now resolved and 28% of systems still appear to show the issue to varying degrees.
The Sontex systems do not appear to have this particular issue, at least not visibly, …