POTTERTON KINGFISHER MF 100 KEEPS RELIGHTING

[ADMO]

Hi all,

I was hoping someone can help. We have a problem with our Potterton Kingfisher MF CF 100 that we can't seem to fix. After around 10 minutes once the boiler has fired up, the flame goes out and the boiler relights. It then continuously does this after every minute. The radiators and water are getting hot but not sure why the boiler flame is going and relighting all the time. The boiler never goes to lockout or we do not have to reset.

The Electronic PCB has already been changed.

 

[CBW]

My guess is there’s still a demand forming somewhere, possibly a motorised valve failure.

 

[stem]

Are you sure that you are not referring to its normal operating sequence?

The temperature of water leaving the boiler is controlled by the boiler thermostat, which controls the burner to keep the water leaving it at the correct temperature. If it didn't, the water would actually boil and anyone touching a radiator would be burned. Older boilers do this by turning the burner 'on' and 'off' as you describe. [Newer boilers achieve the same thing by modulating the flame which increases and decreases its size, rather than turning the flame 'on' and then 'off' completely]

Usually, when the heating first comes on and everything is cold, the demand is higher and the burner will stay on longer. As the system heats up and demand gets less, the 'on' periods will get shorter and the 'off' periods longer.

If on the other hand, the heating and hot water time controls / thermostat are set to be 'off' but the boiler is still operating, then what @The Novice says above applies.

 

[ianmcd]

you need a RGI to check this for you, it could be a safety device that monitors the fans performance dropping out,or the themp sensor could be faulty, but you can not check this yourself, when was the boiler last strip serviced and the fan cleaned ? this appliance is not suitable for just a flue gas analyser check, this must be strip serviced every year, there are a few things that can cause the symptoms that you have , none of which you can rectify as a Diy job,when calling someone out make sure you mention which boiler you have as not everyone will have experience of this boiler, if your heating and HW are working ok and it is doing this all the time and not just when the controls are switched off , it is unlikely to be an external control fault