Draining central heating system - UPDATED Q PLEASE

aliasojo

Another new question please.....I've drained the system down and the water was very light brown. I was quite pleased as I figured it wasn't as dirty as I'd thought.

However, I have a magnaclean fitted and when I took it out to clean it, the magnet was black as was the water inside the magnaclean body.

So am I right in assuming the magnaclean is doing it's job well and the dirt in the system is being caught here which means the rest of the system isn't too bad and I need to keep cleaning / flushing until the magnaclean itself is no longer so dirty?

(Rather than just looking at the water colour that's coming out when draining, I mean. As that's giving a false impression?)