Chlorine In CH Header?

Soldato
Joined
29 Mar 2007
Posts
4,684
Location
Swindon UK
Planning on giving our CH system a clean out with X400 once the radiators go back on in a few weeks. Just over two years since a power flush but it's a very dirty system. I dredged out the header tank in the late Spring and it was heavily contaminated with brown scum and black sludge, which has already started to re-appear. Need to catch it before the cold feed gets blocked again which nearly ended up with the system having a meltdown, last time. I have read the brown stuff is possibly organic in origin, rather than metallic.

So... once the X400 has done its stuff and I drain and refill with nice clean water plus X100 inhibitor and X200 silencer, was thinking about how I can stop the water in the header getting dirty. One idea was to drop in a couple of chlorine tablets, the type you buy for water butts, which would hopefully suppress any bacterial activity. Would this though be liable to interfere with the X100/X200 in the system once the water starts to recirculate, i.e. I don't want a great big foaming mess coming over the top of the header tank and bringing down the upstairs ceiling.

Another option might be to double dose the X100, but essentially that's in the system not sitting stagnant in the header for much of the time.

Long term, the system probably needs replacing with a closed system - Swindon has some of the nastiest hard water in the country which, combined with metallic residue from the pipework creates a nasty primordial ooze in which bacteria thrive. However ATM, make do and mend is cheaper than blowing three or four grand on new CH.
 
Good point. I wasn't planning on overdosing it, just dropping one tab in to try and keep the water from stagnating if it's not circulating.
 
Can you soften the water before you refill it?

You might also put a foam plastic cover on the surface of the water of the header tank (so it floats) to minimise the air surface. Just make sure that it can move freely around the feed pipe.
 
Can you soften the water before you refill it?

You might also put a foam plastic cover on the surface of the water of the header tank (so it floats) to minimise the air surface. Just make sure that it can move freely around the feed pipe.

Not quite sure how that would ever work with a float valve :confused:

Just put cleaning chemicals in the system, run it for a couple weeks, empty and flush the system, refill and add inhibitor. Fit a bylaw 30 kit to your header tank, job done.

Mick
 
The header isn't stagnant the water moves in and out of there as the system heats and cools. If its go that dirty in only two years my guess is there isn't enough inhibitor in it. One thing to keep in mind is that 1 litre of x100 doses 10 panels not 10 rads unless they are all single panel rads (a double rad counts as two panels). A lot of people forget this and under dose their systems. You also want to pour some in the header tank once the system is full.
 
Total 9 rads but being a detached house the circuit is quite large so will heed the advice about extra portion of X100 plus dose the water in the header once the system is full.

As preparation for flushing and cleaning the system I dredged out the header tank at the weekend. Lots of brown water which I guess expands back up through the cold feed (useful for proving its not blocked) but not much evidence of sludge, luckily. So hopefully the X400 clean will leave the system in reasonable overall condition for another couple of years.
 
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