- 27 Jan 2018
- Reaction score
Yea, the ERP pumps are PWM so will help to keep a better spread on the differential, but even on the lowest power setting there still putting through a surprising amount of water, spoke to someone else about that not long ago who said some of the grundphos pumps lowest setting was still way to high to achieve wide temp differences at low gas rates.
What I am surprised is that on the 4xx series they do not expose the PWM output for external pump use, do they only use it for the combi side, what is special about the other boilers that they can use PWM and not regular ones, I find this odd. I have a older 418 before ErP so I would be pre that but I do have a UPS3 but on constant speed.