How to set a bypass valve

[Johntheo5]

I bow to your superior knowledge in these things Johntheo5.

My downstairs heating suffers from terrible TRV noise !. Upstairs far less.

Is this with a setting of CP1, 3M??, if so, I'm quite surprised although I read that some TRVs are more prone to this than others.

The new downstairs pipe runs are much shorter so flow rate will be higher ??.

Somewhat higher but not mad higher except they are of very small ID.

Can / should I try another setting on the pump and if so which.

YES, try PP2, I thought you were doing that??

The head should fall as per graph if you are running presently on CP1.

( my inclination when my issues started, was the water had to much force and was "hitting" the TRVs hard and with heat rapidly)