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Combi - hot water & dirty water


 
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Bullbags

from United Kingdom

Joined: 24 Jun 2007
Posts: 65
Location: Devon,
United Kingdom

PostPosted: Tue Jun 09, 2009 8:41 pm Reply with quote

Could someone help answer the following 2 questions
1) Why does a drop in pressure on a combi system affect h/w operation. I recently drained system down to change some rads. Turned c/h off, left h/w on timed programme. As the c/h is a separate sealed system I didn't think this would affect h/w operation. Had to leave c/h off for a day and h/w stopped working (boiler lockout?). Anyway, altered rads, refilled system and now all ok. Just puzzled as to why h/w was affected when I thought in theory I hadn't touched this. Is it simply that h/w operation requires 1 bar reading to operate too?
2)Have been getting dirty brown water coming out of bath hot tap from combi. If bath not used for a couple of days then dirty water comes out of hot tap and lasts for about 10-15 secs then goes clear. No other taps affected. Why is this happening?
Hope my queries are clear.
Many thanks.
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dreadnoughtheating

from United Kingdom

Joined: 31 May 2009
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Location: Norfolk,
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PostPosted: Tue Jun 09, 2009 8:49 pm Reply with quote

BB, the boiler does indeed require 'pressure" (pressurised water actually I suppose it should be called) to operate.

By dirty water do you mean 'milky'?, if so run it into a clean glass and see if the bubbles clear to the top of the glass. That would indicate nothing more than some dissolved oxygen bubbles trapped in water - sometimes direct from water treatment works, or again, sometimes from getting very hot in the boiler heat exchanger. So, if milky nuffink at all to be concerned about.

DH
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Bullbags

from United Kingdom

Joined: 24 Jun 2007
Posts: 65
Location: Devon,
United Kingdom

PostPosted: Tue Jun 09, 2009 8:57 pm Reply with quote

Thanks DH. Water not milky, it's dark brown. Similar in colour to what you would get when bailing out the bottom of a header tank.
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dreadnoughtheating

from United Kingdom

Joined: 31 May 2009
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Location: Norfolk,
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PostPosted: Tue Jun 09, 2009 9:05 pm Reply with quote

Hmmmm, waters mixing in a split secondary heat exchanger? - Not good, get an RGI to visit. If you are in an NR postcode area, reply and we'll make contact.

DH
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sooey

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PostPosted: Tue Jun 09, 2009 9:11 pm Reply with quote

You say you 'left h/w on a timed programme'. Are you sure you've got a combi? Do you have a hot water cylinder?
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kevindgas

from United Kingdom

Joined: 28 Mar 2006
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Location: Southampton,
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PostPosted: Tue Jun 09, 2009 10:41 pm Reply with quote

dreadnoughtheating wrote:
if you are in an NR postcode area, reply and we'll make contact.

DH

don't think Devon is NR postcode somehow icon_lol.gif icon_lol.gif
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dreadnoughtheating

from United Kingdom

Joined: 31 May 2009
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Location: Norfolk,
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PostPosted: Wed Jun 10, 2009 3:46 pm Reply with quote

kevindgas wrote:
dreadnoughtheating wrote:
if you are in an NR postcode area, reply and we'll make contact.

DH

don't think Devon is NR postcode somehow icon_lol.gif icon_lol.gif


OK, OK, so give the 'new boy on here' a break can't you? I know things are quiet business wise and yes, Devon is outside my normal work area but you can't blame a bloke for trying icon_wink.gif

So, if it is a 'Combi', is the filling loop left connected?, although the checkvalve in the loop is not supposed to let system water through, may be its a home brewed job...... just a thought
DH
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gigz

from United Kingdom

Joined: 07 Oct 2006
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Location: United Kingdom
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PostPosted: Wed Jun 10, 2009 4:17 pm Reply with quote

Bullbags wrote:
If bath not used for a couple of days then dirty water comes out of hot tap and lasts for about 10-15 secs then goes clear. No other taps affected


If no other tap is affected i would say its the pipework to that tap i.e. iron pipe or a rusty/split flexi or even the tap itself.
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jmln

from United Kingdom

Joined: 21 Apr 2010
Posts: 1
Location: United Kingdom

PostPosted: Wed Apr 21, 2010 6:04 pm Reply with quote

The brown colour experienced when the tap is not used for a while is iron and is a natural element in water - it is in all ground water in different degrees, however, it is made worse when passed through metal pipes currently being changed to blue plastic as fast as the utilities can afford. Old properties also used iron pipes, again only changing them will remove some of the problem. The water companies will try and reduce it but there will always be some present. I have used a slow sand filter to remove it from a water source down to a tiny amount - it is said to be harmless but it not pleasant to drink it. It is strange how it only shows when it stands due to oxidation which turns it brown as in rust, more so when warmer. If you look inside a storage tank apart from discoloration on the tank sides there is also a furry film that attaches itself to plastic pipes because the two have different static charges which attract this is also evident in plastic pipe inside walls so that when the tap is turned on it flushes away, this is a bacterium of iron normally invisible until static. Copper pipes have a sanitising effect which prevents this occurance so beware when choosing plastic water pipes although the water companies are using it as a replacement to metal. If you choose copper for the last supply chain you should not get any of this through the tap.


Last edited by jmln on Wed Apr 21, 2010 8:25 pm, edited 2 times in total
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Boilerman2

from United Kingdom

Joined: 10 Jun 2009
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Location: Suffolk,
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PostPosted: Wed Apr 21, 2010 6:08 pm Reply with quote

That's Deveon Soft water for you icon_lol.gif
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