C H Boiler

[whistonian]

When my C H overflow pipe drips it leaves a blackish/grey mark on the path,so i assume that it is not clean water dripping out.Can anyone explain what causes this ?

[albaqwerty]

from what I remember of the last visit from a boiler-man, he said the water, although supposedly in a sealed system isn't pure due to it going round the pipes etc
(should have paid more attention to his explanation, sorry, but he did mention something about acids accumulating)

[albaqwerty]

and why does the pipe drip? Please get it checked, water pressure is vital to these brutes

[murraymints]

if it is a condenser style boiler then I think there usually is a drip from condensation on the outside wall... the sysyem also has additives for circulation anti rusting etc... so I was told anyway when something or another was added at some cost !!

[whistonian]

Thank you for your answers,I am due a boiler service shortly so i will ask about it then.Both your replies do seem to make sense.