I’ve also been doing some maximum capacity testing with my 5kW Samsung R32 ( AE050RXYDEG-EU Gen6). My house has a heat loss of about 3.5kW, so I usually run it well below its maximum output, here’s a 12 month update video I did a while back with lots of info on my system.
I tried to find weather conditions to test the unit under worst case defrost, here’s the official capacity graph for my unit, at 40C flow at 2C outside it should be able to output 4.3kW, apparently this data includes the effect of defrosts. According to datasheet 2C ambient should be the worst condition for defrosts and result in the lowest capacity output.
For completeness I would like to do a max capacity test in sub-zero conditions, counterintuitively according to the official data the unit should have a higher capacity at sub-zero temps since effects of defrosting should be less
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Conclusion
The unit seem to consistently output about 10% higher than the rated figures.
I’m rather impressed by this, after 12 months of never running the flow temperature higher than about 36C for space heating it’s rather impressive to experience how much heat 45-50C flow temperature can output! Also, the COP of around 3.3 while running at max output was higher than I expected.
During the test I set the flow temperature target to 55C, it never reached 55C, once it reached 51C, but mostly it reached around 45C. This indicates that a heating system using this heat pump should not be designed to require a flow temperature higher than 45C.
That’s probably a function of radiator output rather than the heat pump?
Given the available emitter area they dump the heat as quickly as it arrives at a flow temp of 45C or so.
You could design to have smaller emitters and it would then reach higher flow temperatures.
Anecdotally agree. We’re now comfortably below zero and the interval between defrosts at -7C or so is materially longer than the interval around -1C for the little “AC” optimised split currently doing heating duties at our place. (defrosting for 10 mins of every 30)
Defrosting will have a disproportionate impact on capacity at the milder UK design temperatures vs continental ones; and not just the weather but also the time spent defrosting (how quickly the unit can defrost / how quickly it dares to defrost / how quickly it dares to resume heating at full chat - on the assumption that there is both a capacity constraint AND some expansion/contraction/thermal shock/plinky-plinky noises from pipework moving type considerations at play)
