Why is My boiler Making a Noise like a Trumpet

My boiler is making a loud trumpet like sound and winding up neighbours. This was something we came across recently on an Ideal Evomax 120 and 150. Having searched on google we could find nothing to help us locate the problem so we decided to post it ourselves in case others come across the same issue.

The fan in the boiler pulls off the burner plate. In some cases over time the burner plate can become very slightly bowed. When air blows over a bowed burner plate it causes the same effect as blowing a flute. This is what makes the trumpet/flute like sound. If the boiler flue then goes into a chimney the noise is amplified up the chimney causing a loud trumpet sound.

A very simple fix to this is to simply replace the burner plate and problem solved. Sometimes the burner plate will only need a good clean and this will be enough to stop the sound but it is not usually a permanent fix.