Hello there hope someone can help i have a ariston eurocombi boiler which at the moment works ok. But i have noticed lately that when turn on the C/H for the first 10 minutes while it is warming up there is a loud continous clicking noise once it has reached a certain temp the noise seems to stop. This also happens when i am drawing H/W it baffles me as the boiler was serviced not that long ago and given a clean bill of health?