My Grohe mixer is fed from a hot/cold pump. The cold is mains pressure and the hot is fed from a loft tank so the head is around 4 feet. The pressure at 38C temp was very acceptable when new 8 years ago but now the pressure is too low at this temperature. If I reduce the temeperature by rotating the mixer the pressure returns to normal but the temperature is too low.
I have changed the shower head and flexible tube but this does not improve the pressure. I also tried lifting the hot tank temperature but this did not improve the pressure.
There is a maximum temperature limit adjustment on the mixer accessed by removing the knob and rotating a inner knurled knob but this just sets the temperature higher before the knob stop position is reached.
There is no air in the pump so can anyone advise why this is happening and how I can fix it?
regards,
"nobody"