Hello,

The orange colour will be a mixture of oxidised metals (rust for
iron). With what is known as an open vented system (feed and
expansion tank) as you have the system is open to atmosphere and
therefore air (oxygen) will be able to enter the system and encourage
oxidisation of the metals in your system. Putting inhibitor in your
system is a good idea. however, you can also add a system restorer
and then drain it out a week later and then add the inhibitor...

http://www.plumbers-central-london.co.uk



On 27 Jan, 13:47, wrote:
Hello,

Whilst in the loft I noticed that the water in the CH header tank was
murky and foul smelling. There was also something orange on the water
line: either a deposit or a fungus?

I'm pretty sure it's not supposed to be like this! I put a bottle of
Sentinel inhibitor into the tank when I moved in, so I thought I would
have been protected? What should I do: should I drain down and refill
and use two bottles next time? What is the orange likely to be? Surely
copper compounds are usually green or black? I'm thinking iron
compounds are orange: oh oh!

Thanks.