Brown water in CH Expansion tank

[donniall]

Hi,

I have noticed recently that the water in the small expansion tank for the CH system looks dark 'brown like'. As it gets its water directly from a clean water feed I cannot understand where this 'stuff' is coming from? Would chemicals (such as Sentinel X100) overtime introduce water discoloration?

Also, and as a consequence of above, I wish to drain down the entire system and possibly use a sludge remover (Sentinel X400?) to remove sludge etc ... I have two drain points: one just over the boiler situated in the kitchen (for upstairs radiators), and another downstairs which is closely positioned to a door/drain-way (for downstairs radiators). If I just drain from this latter point is that ok? I would imagine draining from the lowest point should ensure that I darin everything .... and avoids me having to use the boiler darin-point which is a complete pig to access!! A colleague suggested that if I open all vents before draining it makes the whole process much faster, and complete?

Any help greatly appreciated!

Don-

 

[JohnD]

...I cannot understand where this 'stuff' is coming from...

steel radiators + water + dissolved air = rust

(there's a bit more to it, but that will do).

 

[donniall]

Thanks for the reply ...
I guess the bit I dont understand is how its getting into the expansion tank (admittedely my knowledge is limited in this area!).
Will it suffice to drain the system from a single point, rather than two points that exist, and if I open all vents does that quicken the process?

Many thanks again,

Don

 

[JohnD]

It is fine particles which flow around with the water. It will tend to settle at the lowest point, but as it is pumped round, some of it will get into the expansion tank as the water rises and falls with expansion as it gets hot.

Bale out what sludge you can from the F&E first.

You will want to drain mostly from the bottom, but open the other as there may be a loop in the pipework. You have to open the rad vents to let air in so the water can get out.

Flush it through a few times to get the loose stuff out. Then use your chemical cleaner.

 

[donniall]

many thanks mate!!