Boiler kettling

[sand100]

I had new Grant 50/70 standard (external)oil fired boiler fitted to an existing system a year ago.
When the boiler reaches temp there is a hissing bubling noise just before the boiler stat cuts out ,the noise tranfers through pipework to pipes inside house.
The boiler stat is set just above half way
The pump mounted internaly on the return is set at the middle speed.
The temp of flow pipe at top of boiler is 65 deg
The system was flushed through at commisioning.
Fernox protector was added.
All radiators are working ok no hot or cold spots
Did not get any kettling from the old boiler.

I have tried
Draining and refilling system
Turning pump speed up
turning pump down (noise was worse)
Turning boiler thermostat up ( Noise lasted longer)
Turning boiler stat down (radiators not quite hot eneugh for the for cold nights

Questions
Will fernox boiler silencer work. we live in a very soft water area so I dont think limescale is a major problem.
any other sugestions ?

 

[sand100]

I have now partitialy drained the system and added Sentinel X100 & Sentinell X200 noise reducer, then refilled the system, now after a few days the niose has almost disapeared. Also a hissing from one the TRVs has stopped.
Good outcome.

 

[wilhelm]

you could have tried some ceraboard.