I have a Potterton Suprima 50L that is 10 years old. I fitted a new PCB in May 08 to get rid of the known lock out issue caused by dodgy a PCB and it worked fine until a few weeks ago. I replaced the PCB again today and the fault has not gone away.
The problem shows itself up when the central heating is on. The boiler starts its sequence: fan on, gas lights and burns for 5 seconds then boiler stops with a flashing green light which means the boiler thinks it is up to temperature. I have changed the thermister but the problem is still there. I measured the resistance of the thermister and it matches the value Potterton say it should be.
If I run some hot water off, the cylinder stat operates so there is a demand for heat from the boiler. The boiler fires up fine and stays on until the water is up to temperature. Because the timer is still set for central heating and hot water, the mid position diverter valve lets the hot water from the boiler into both the cylinder and radiators so I get a warm house.
The PCB kit comes with all new cables including the one to the spark thingy.
Any ideas how to fix this as I can't keep having showers or running water off?
The problem shows itself up when the central heating is on. The boiler starts its sequence: fan on, gas lights and burns for 5 seconds then boiler stops with a flashing green light which means the boiler thinks it is up to temperature. I have changed the thermister but the problem is still there. I measured the resistance of the thermister and it matches the value Potterton say it should be.
If I run some hot water off, the cylinder stat operates so there is a demand for heat from the boiler. The boiler fires up fine and stays on until the water is up to temperature. Because the timer is still set for central heating and hot water, the mid position diverter valve lets the hot water from the boiler into both the cylinder and radiators so I get a warm house.
The PCB kit comes with all new cables including the one to the spark thingy.
Any ideas how to fix this as I can't keep having showers or running water off?