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Boiler making loud banging noise

Postby CWilliams » Tue Mar 23, 2010 2:34 pm

I have a Baxi105e and recently it has started making a lound banging noise when either the CH or the DHW makes the boiler fire up. It happens when the water is reaching the thermostat temperature. Ive noticed that the pressure gauge flicks between 1.5 and 2.5 when this happens. Ive been told that its an airlock or the Heat Exchanger?? is clogged up. Ive bled all the radiators and the pump lets out a trickle of water if i loosen the screw on the front. Is there anything i can try apart from finding the money to call someone in. A few years ago i had to change two of the radiator thermostats so im ok with draining the system and removing radiators etc.
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Simply Build It

Postby htg engineer » Wed Mar 24, 2010 10:22 am

It could be the gas pressures/modulation, if set wrong or not modulating the heat will struggle to get away from the boiler.

Check flame picture, set HW to MAX, run hot tap - before the noise starts the gas rate should reduce (you will see the flame size decrease) when the MAX temp is met.

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Postby Mathmos » Thu Apr 01, 2010 6:59 pm

Check the boiler condense trap/pipework is not blocked first
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Postby BoilerEngineer » Thu Feb 23, 2017 5:21 pm

Boilers make noise for many reasons. Boiler engineers often refer to the noise as ‘kettling’. They usually divide the causes for it into two groups, chemical and mechanical.

A foaming system can lead to overheating. The chemical water reduces contact between the water and the heat exchange. The foam which is responsible for this overheating is mostly due to residuals, suspended solids, or other contamination.

Boilers make noise because deposits insulate and partial insulation of the heat exchange surface can cause uneven heating. In central heating systems, such deposits will likely be corrosion debris or thin limescale deposits.
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