Daikin heat pump 11kw

Hi we just installed a brand new daikin heat pump of 11kw which is doing only underfloor heating only the system was on gas before which is 12 years old the new client who has brought the house has never used it, we have flush the old water out and a cleaner and added new water also have no leaks we got all the air out pressure on bar is 2,5 bar the running temperature is 45 degrees all the mainfolds are heating up and pipes to each room this runs for 3 to 4 hours then cuts of with water flow on the display can any one help

If the unit is faulting on water flow then you need to be looking at the actual water flow through the system.

Do you have any automatic bypass valve installed? As the heads on the UFH maniflod shut, the pump needs to maintain flow through the HE via the bypass valve until such time as the unit shuts down on temperature and the pump stops.

Hi we have a automatic by pass installed we also had daikin come and check the install said will work correct what’s the best temp to run this he said 45 which we have left on

The temp setting of 45C is fine.
When the system is working are you able to measure the flow and return water temperatures?

You should have 6K difference, so, if you have a leaving water temp of 45C, you should have a return temperature of 39C. The 6K difference will indicate the correct flow rate.

Hi we have 37 but still cutting of no dirt in system

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.

Thanks I will check

Is this a Daikin "B" or "C" type unit as the water flow is sensed differently?
As Frank has mentioned, it sounds as if when some of the UFH heads are closing that you are then not getting the correct flow rate.
As a rough guide, each UFH loop should have approximately 2-2.5litres/minute. If you have not got this, then that should be the first place to check and possibly adjsut the individual flow rate.

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

Thanks I will do this