GEM combi, fault burner keeps going out then relighting

[lotusfrontera]

I know its a bit old now but I`ve got a GEM combi boiler and in the past managed to keep it going In the past I`ve changed flow switch(twice) , the diverter valve, and just a couple of months ago the pump. The problem I have now is if the hot water is required(tap turned on) the boiler does not light for quite awhile, and once lit it pulses on and off for a long period(which is getting longer) until it finally stabilisers. This on and off of the burner also happens on central heating but not as extreme.
Apart from this boiler runs ok over limit does not trip out etc.
Hopefully someone will be able to point me in the right direction.
cheers in Advance,
Dave.

 

[Agile]

This is likely to be a gas fault which is not suitable for a DIY repair.

As you have said its an old boiler so it might be time to consider replacement.

Because they are rather rare you might also have some problem finding a boiler engineer who is comfortable with them as they are now quite rare.

Tony

 

[lotusfrontera]

Hi Tony,
Thanks for the reply. So do you think modulator or gas valve? Or could it be just low pressure??
Have managed in the past to get spares from european spares ltd.
If you can shed anymore light it would be useful,
cheers again,
Dave.

 

[Agile]

I am sorry but we are not allowed to give advice on gas work on thisd forum.

Without being in front of the boiler and responding to the results of tests that I cannot make any further suggestions.

I dont expect its anything very terminal though.

Tony

 

[lotusfrontera]

Thanks again Tony, I understand where you`re coming from
Managed to have a little look last night and voltage to modulator was up and down for a short while. But luckily after doing some testing the unit seemed to stabilise, so may have a dry joint on Driver board, but I`m also looking at thermister as a culprit