appollo fanfare banging boiler a minute after ignition help

[harrysmum3]

We have a apollo fanfare and when it first starts up in the morning after a minute it bangs then turns off then it starts again and it is fine all day untill the next morning and then it starts again.We had a new pump fitted and we had the auto bleed radiator valves put on as there was air in the rads there is enough water in the expansion tank and which is open air and the water has been drained and clean water added with fernox the boiler is old but it goes fine all day and we just have the problem on the first ignition all the time. can anyone give us some advice please.

 

[twgas]

I would think the pump overrun stat is dodgy - slow to switch accross hence stopping the pump and allowing the boiler to overheat.

 

[gavinda]

seconded.

 

[gas4you]

I can't really see this as it happens so quickly

Pump over run on these is not a standard type, it works off the general heat inside the case.

Pump should still run in normal mode whether overrun stat is faulty or not, but may not over run when needed, or keep on all the tme

 

[gavinda]

this is the one that 'sticks' in the evenings and mornings. its just a little disc in the lower left. from the symtomps i wouldnt suspect much else. it could be a sticky pump in the morning but from experience i'd go for the stat 1st.

 

[harrysmum3]

thankyou for your help how do you fix this stat and would it be expensive we have had british gas out as we have cover with them and it never makes the noise with them there but they just say the boiler is old and needs replacing but as it goes fine all day we do not understand the problem

 

[harrysmum3]

I just wanted to add that the boiler goes for about 4 to 5 mins before it bangs not just 1 minute I dont know if that helps is there any answer out there we are worried about the safty of the boiler thankyou

 

[gavinda]

ask for a fresh engineer.... older ones may know this, twas an old boy told me