Daikin heat pump 11kw

[frank]

So you have 8K between flow and return which indicates that the flow is too low. This obviously is leading to your 7H error (low flow).
From here I can't see why so you must look at all aspects of the water flow through the system.
Is the pump set to speed 3?
Is your auto bypass valve set up correctly?
Are the pipes sized correctly?

Lots more questions ...such as - is the flow switch faulty, etc.
......Try to think logically, and eliminate things 1 x 1 until you get to the cause of the issue. If the system runs OK for 3 to 4 hours without fault then I would be looking at what is happening with the UFH manifold heads closing down and starving flow as they reach temp and possibly the bypass valve not being set up correctly.

[nike123]

This is probably problem with unbalnced system.
Give us some details and pictures about distribution manifolds and flow regulation. Also unit model.

[eurocooling]

Thanks I will do this