It doesn’t seem to have any issue clearing the fins, as far as I can tell. I’ve got a lot of system volume, maybe that makes a difference.
Maybe I’ll experiment over the weekend but, without OEM kit, I’d have to lap time the defrosts and look at the HPI for flow temp data to have any idea what’s going on.
Can see the effect NR mode can have on this other Vaillant:
After the change at 07:15, can see fewer defrosts and better COP (2.5 → 2.7), though less heat going into the house overall (4.2 → 3 kW). Doesn’t seem to have affected internal temperature all that much (UFH emitters).
What would a reduction in requested flow temperature without ND mode do?
Does the “energy going into the building” take into account energy removed for defrosts?
The heatpump will likely have a big spike of power at the start of each cycle, which then settles down a bit once flow temperature has reached the lower target.
IMHO, it’s better to keep the power limited if the full power of the heatpump isn’t needed. See this example, where NR mode was enabled at 00:00, while still reaching the same flow temperature. Note how the spikes of power at the start of each cycle are reduced. Heating power only slightly lower overall (3.6 → 3.3 kW).
In this case, yes it does. Defrosts have subtracted ~8% of the heat output for the chart above.
It a shame compressor speed can’t be limited while fan is on max speed, as moving more air past coil will likely give higher COP.
