Boiler lockout

[khab2792]

Potterton Suprima 30
Loft expansion tank.
Conventional non-pressurised hot water tank

Boiler is noisy and often sounds like the water is bubbling inside. The radiators fill with air. The boiler then locks out.

I bleed the radiators but the whole cycle starts again every other day or so. I have checked the expansion tank. This is full of water and so I presume this is not the source of the problem.

Any ideas?

Thanks,
Tim

 

[corgiman]

it sounds like a savage sludge build up

Over to Tony He likes these

 

[khab2792]

Thanks,

I didn't realise a little sludge could produce this much of a problem. Out f interest, are these small microbore pipes used in many new domestic installations the problem?

 

[Agile]

I dont like Suprimas although I repair quite a few.

Just because the header tank is full it does not mean that its connected to the rest of the system.

One of the most common faults on an open vented system is a blocked feed pipe.

Tie up the ball valve and drain a few litres of water from a rad and see if the level goes down.

I have never heard of any systems being fitted using microbore for a very long time.

Tony