Yes, lime scale so DS3 ( sulphamic acid ) is appropriate to treat it.
As explained above its not very soluble so several goes will be needed.
Tell us how you get on. Newgas is very interested in this!
Have you seen what temperature its tripping at? Watch the gauge until you hear the click ( or feel the pin come out ). Its actually hotter than the indicated temperature because of the position of the sensor.
When you have fixed it I will tell you how to reduce the CH power as this being mis set will have contributed to the scaling. Its often resulting from incorrect commissioning.
Tony
As explained above its not very soluble so several goes will be needed.
Tell us how you get on. Newgas is very interested in this!
Have you seen what temperature its tripping at? Watch the gauge until you hear the click ( or feel the pin come out ). Its actually hotter than the indicated temperature because of the position of the sensor.
When you have fixed it I will tell you how to reduce the CH power as this being mis set will have contributed to the scaling. Its often resulting from incorrect commissioning.
Tony