potterton performa 24 clunking and overheating

[Cozza4301]

I had my boiler repaired today as it had stopped working entirely, it was not firing up for HW or CH. The boiler engineer said there was a loose connection as the fan was not kicking in. He fixed it and it all worked. A few hours down the line it started making a terrible clunking noise, like the sound of a pump running dry, I could hear hissing and the pressure gauge was shooting up and down so I turned the whole thing off. My engineer came back and said the boiler was overheating. He suggested it could be the primary heat exchanger. We are using it for HW and it is ok (I believe the HW is a separate heat ex?). We have also kept the heating on but just turn it off after an hour before it overheats again.
The boiler engineer suggests it could be lack of chemicals in the system that have caused the exchanger to scale up.
Does it sound like the primary heat ex that has gone?

 

[Cozza4301]

Anyone out there??

 

[MC2012]

I would get him back to check that he hasn't turned off either flow or return isolation valves, these are prone to break, they look on but may have only opened slightly.

Matt

 

[Agile]

yet again we see that you have had someone who does not seem to have any idea of how to fix boilers.

Why should we have to tell you what to tell him to do?

There are a few possibilities and being at the boiler is the only way to see exactly what is wrong in your case.

You could in theory check the black knobs at least look in place.

Tony