Sorry for the late reply. I got my Grundfos pump from Midsummer Energy. It included the PWM cable. Be sure to check the model carefully, not all Grundfos pumps support PWM.
That’s not correct, on my Gen6 PWM will modulate the pump to maintain DT at any flow temperature e.g 30C
Here’s a link to view my data: Emoncms - app view dashboard
I don’t think this is true, I’ve observed PWM being active during DHW, it seems to modulate down to 17 L/min, without PWM my pump will run at 22 L/min.
However, I did need to update my firmware to get PWM to work. The dataplate on my HP says it was manufactured in 2021:
For the first year I ran my HP without PWM, I’ve just come to the end of my 2nd year with the HP, this time with PWM enabled. This year I go a SCOP of 4.45 compared to 4.19 in the first year. I think PWM has helped with this 0.26 increase in SCOP, although it’s hard to say for sure.