Our central heating is a 60 YO hot water system. The water tanks (not sure are they connected?) were changed 2 years ago and wealso converted from mazout to electric for the energy source not long after.
Last week we changed some pipes and had to empty the water from the system.
The water came out black!
I've been looking up to see if it was fine and found opposit opinions. In North America (where I live) the sites seem to say it's no big deal put fresh water in basta or leave it as it is, it's normal.
On the french sites they said you need to get a specialist in to clean it properly, it can damage you system and limit it's life expectancy.
Some said change the water every year and others said keeping the old water is best (less oxygen in the water)
I'm quite confused, what is the best way to treat a hot water system so that it lasts for ever a long time? Am I supposed to do something about the black water?