combi boiler flame problem

[happyhenry]

the problem is this when dhw is called system starts and when you look through viewing hole there is a nice even for a while this then expands to a large orange flame and temp rises rapidly causing boiloer to shutdown for a period of time.

any ideas b4 i call out my local engineers so i can at least not get had over never needed one b4

 

[giblets]

What boiler have you got?

 

[happyhenry]

a jaguar 28 i believe it is also a variation of a protherm boiler 28kv
used to be sold by plumbcenter

 

[giblets]

Could be an internal water leak onto the burner.

Why post the same question twice?

 

[happyhenry]

i didnt think i explained it well in first one sorry for confusion.

but if i had a leak on to the burner wouldnt i see some sort of evidence of water or corrosion.

 

[giblets]

Not necessarily. How long have you been noticing the "change" in flame height/colour?

 

[happyhenry]

hi giblet, thanks for your responses,
i only noticed this last night when the wife couldnt get a hot bath it also does the same on the ch side to

i have taken off the plate that covers the burners everything isolated i might add and there is no evidence of water leakage but in the rear right side there is large amount of soot on the fins of the heat exchanger i have cleaned as best i could.

when i watched it closely it defianetly looks as though there is an increase in gas and the flame gets bigger b4 going orange

 

[giblets]

Methinks it is time to get a man in. Soot is not good news.

 

[happyhenry]

happy days are here again....

the man came round looked at the problem and then promptly removed the fan unit cleaned it out etc and da...daa it works again got him to service at the same time all done in hour and a half he is going to come back and flush system though...

he said the boiler is self modulating and the boiler wasnt getting enough air from fan so it burns orange creates soot etc and clogs even worse although he did say if it comes back will have too probably replace fan unit £110 plus labour

hope this may help someone in the future