Hopefully someone may have an answer to my problematic boiler.
The problem is that the overheat cut out keeps tripping. My engineer has replaced the pump, gas valve, boiler thermostat and thermocouple over the past few months but the problem still persists. We have recently flushed through after adding a system cleaner but still no improvement. His opinion, due to having replaced the obvious causes, was that the heat was not getting away from the boiler quick enough due to the pipework or heat exchanger being partially blocked. I can fully understand this point of view except for one reason.....
When the boiler is lit and the controls are switched on, the boiler will flash up and run for a certain period of time. Once the water is at the temperature selected on the boiler thermostat, the main burners cut out leaving just the pilot, just as it should. However, around 15 seconds later there is a click and the overheat cut out shuts off the pilot. However, if for example I set the boiler thermostat to low, start it up and let it run until it cuts out, the overheat still clicks in after around 15 seconds. But, if I do the same again i.e. run the boiler with thermostat on low, then, as soon as it cuts out, I increase the temp on the boiler thermostat before the overheat cut out clicks in, the boiler will flash up and keep burning until it reaches the new temperature and then cuts out. The overheat still cuts in around 15 seconds after this.
Surely, if the problem was due to heat not getting away from the heat exchanger, and the cut out tripping on a low temperature setting, then I would not be able to increase the boiler thermostat and get the boiler to burn for much longer?
Any help appreciated.
The problem is that the overheat cut out keeps tripping. My engineer has replaced the pump, gas valve, boiler thermostat and thermocouple over the past few months but the problem still persists. We have recently flushed through after adding a system cleaner but still no improvement. His opinion, due to having replaced the obvious causes, was that the heat was not getting away from the boiler quick enough due to the pipework or heat exchanger being partially blocked. I can fully understand this point of view except for one reason.....
When the boiler is lit and the controls are switched on, the boiler will flash up and run for a certain period of time. Once the water is at the temperature selected on the boiler thermostat, the main burners cut out leaving just the pilot, just as it should. However, around 15 seconds later there is a click and the overheat cut out shuts off the pilot. However, if for example I set the boiler thermostat to low, start it up and let it run until it cuts out, the overheat still clicks in after around 15 seconds. But, if I do the same again i.e. run the boiler with thermostat on low, then, as soon as it cuts out, I increase the temp on the boiler thermostat before the overheat cut out clicks in, the boiler will flash up and keep burning until it reaches the new temperature and then cuts out. The overheat still cuts in around 15 seconds after this.
Surely, if the problem was due to heat not getting away from the heat exchanger, and the cut out tripping on a low temperature setting, then I would not be able to increase the boiler thermostat and get the boiler to burn for much longer?
Any help appreciated.
