how can I fix F75 on my ecoTEC exclusive 832. I have installed it 3 years ago. in the first 2 years it has failed and shown F22 almost every two month. I have been told by my plumber to pump up pressure to the system so, that have been doing, then in March 2013 it's has shown F75. I pump up the pressure again but it wasn't work any more. I called valiant engineer, they came and end up with changing sensor unit. Now I have F75 again i did pump pressure up to nearly full but still doesn't work. Any idea what was cause and how to fix it please.

sas, July 2013

F 22 and F 75 both change water pressure but main problem is pump not doing job also auto vent on pump blocked ,just change pump ,fill water to 1.2 bar no more problem for long time,

ltd, July 2013