Boiler Service cost - unresonabley high? Conflicted.

[robinbanks]

The hissing/popping noise that indicates some part of the water is boiling

For example when you put a kettle full of water on an it starts with noises/bubbles attached to the element, but the bubbles are absorbed back into the cooler water above without becoming a rolling boil (air bubbles coming to the surface). Unusually indicative that the thing is not far off breaking into a full boil

 

[Agile]

Normally described on boilers as an irregular rapid knocking noise.

Usually caused by calcium deposits within the main heat exchanger.

Most common on older boilers with cast iron heat exchangers.

Usually easy to cure with the right chemicals and a little experience.