Hi, finally the update.
Potterton sent an engineer. Note that here in Ireland this visit has to be arranged through the plumber who did the installation..
Engineer confirmed that the plumber had set everything up correctly and that the pipe size was ok too, and that the noise was 'normal'. As...
Hi,
this boiler has been installed 2 weeks ago. Whenever the heating comes on a loud hum / whine starts. I suspect it\\\'s the flow speed which may be too high. The prev. boiler was an older Potterton model with a separate pump, when this was set to \\\'high\\\' the exact same noise happened...