I have a working boiler that though running is not getting the radiators or hot water more than lukewarm... I first thought was it was a fault on the water temp sensor on the boiler so I changed the sensor.. no change.. any suggestions keithice
Problem may be with the gas valve not modulating up to full gas rate. Check the burner gas pressure and compare readings with manufacturers spec. If this is the case you are looking at the PCB or the modulating gas valve assembly.
I too have this problem and replaced the temperature thermistor today but no change. The problem seems to be intermittant and it will run hot for several hours before running lukewarm again. Has anyone had any success in sorting this problem?
In case anyone is interested, I solved my intermitant problem by just turning the boiler thermostat down. I had turned it up to maximum during the cold weather thinking this would help heat my house better, but for whatever reason, this caused the fault described above. All running fine now.