Hi
The chalk that you refer to is probably soft limescale do not add any kind of acid to your water system as it may attack soldered joints etc . heres a link that might help if you have a combl boiler
http://www.pflush.com/combi-boiler-descale.html
Graham
November 2009
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
