CoyoteOldMan Based on the schematic you posted above, from the pump, the flow has got to go across: check valve, flow meter, heat exchanger, the various components in the grouphead, the solenoid, and all the pipes connecting the above. At least one of those is blocked - that’s rather more than the two pipes (which ones? Those marked 22 and 23?) and the grouphead filter and jet/gicleur… (at least that’s what I understand you have checked/cleaned).
Thanks, yes I removed no 22 and the return pipe from the group head to the left of number 23 (cold supply hose) there’s three pipes going into the bottom of the heat exchanger the one I cleaned, the cold supply hose (23) to the HEX and the other one goes to expansion valve then to outlet/drip tray.
The group head is clear as is the solenoid valve (new) I also cleaned the brass dispersion plate (ten holes), the shower screen and jet.
Interestingly most the pipework around the pressure stat have been removed previously there’s PTFE at all of the joints.
