Hi Lukas, I’m new to community so only just seen your post. I have an 8kW Samsung Mono Quiet so not identical but similar.
- As Glyn observed, there is no ASHP flow temp constraint for DHW (unlike the WL settings for CH). So the ASHP winds itself up to a high temp (with consequent high power requirement) until the hot tank temp setpoint is reached. I’ve moaned to Samsung about this to no avail (“no consumer demand for adding such an FSV”). This may be because most folk have DHW on 24/7 and the few minute’s top up takes hardly any power.
- Samsung advise at least 2m2 coil area (pref 3m2) for 8kW unit to limit this temp wind-up, so your 0.7m2 explains the high power you see. I have 0.9m2 (I retained my old tank) but as I only enable DHW 2 days per week I can’t justify a new tank/coil.
- I mitigate the high power during DHW demand by splitting scheduled heating time (2 x 15min bursts with 15min in between). This drops peak power demand by ~50% by giving the tank chance to convect some heat.
- You really need the tank temp sensor near the bottom, otherwise most of the tank will not be heated.
- Unless I misunderstand your numbers, your DHW CoP is simply 29/12 = 2.4 (not the 3.4 you posted). But happy to be re-educated…