Hi,
I fail to see how inverter heat-pumps can be more efficient than fixed- speed ones.
I guess this boils down to another question: a heat-pump probably has a speed where its efficiency is maximum. Hopefully this is where fixed- speed heat-pumps are set to operate. Is that right?
If so, when the inverter varies the speed, it moves away from the optimum, and efficiency goes down.
It would seem to me, from a pure COP view point, and if my assumptions are correct, that a fixed-speed heat-pump would have the maximum efficiency. Now, comfort is also important, and off-on maximum heating a not as nice as sustained, adapted, heating.
But this is not what is advertised. All vendors claim that COP is better with an inverter, even though i assume there are lossses in the current-inverting circuitry. How can that be? The only way I can see that this would be true is if the COP increases as compressor speed decreases, but I was never able to find any information about that.
And also -this is presumably linked- why do smaller heap-pumps have a better COP than larger capacity ones?
Does anyone know the answer to this mystery?
Thanks you for your lights, Chris