bigandy
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| posted on 10/11/06 at 10:18 PM |
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Combi-Boiler/Central HEating question
Evening folks.
We've just had the gasman out to do a service and inspection, and he has recommended we get a new combi boiler fitted in order to stop a rpoblem
we have been having for ages now.
Basically, if the hot tap is left on for a while (say when having a shower) when it is turned off, the pilot light is turned off due to the boiler
overheating. It is a cheap and old boiler (about 13 years old) and I am reluctant to replace it as I am looking for a new house in the new year.
As an alternative the chap recommended that we have the system flushed out, as he thinks it may be crap and scale in the boiler that is causing it to
retain heat, and overheat when the hot tap is turned off. It sounds fair enough to me, and the system has not been flushed by me in 3 years, or the
previous owners in the 5 before that.
So, I was wondering what is involoved with the flushing lark, as the cha I spoke to said it would be around 400-500 quid, and they pump posh chemicals
in to clean it out, and flush out all the scale and crap, before pumping in new chemicals to preserve the system for the future.
It seemde awfully expensive to me (although I have got another chap coming round next week to give me another quote), so is it something that can be
done DIY?
Any help would be much appreciated!
Cheers
Andy
Dammit! Too many decisions....
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Deckman001
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| posted on 10/11/06 at 10:37 PM |
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I was quoted about the same cost for the same thing, I just flushed the system meself and the problem only comes back occationally now. Sorry, but
powerflushes are expensive 
Jason
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MkIndy7
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| posted on 10/11/06 at 10:37 PM |
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Yup can most certainly be a DIY job, espescially if it only had to last till the New year.
There's lots of different ways of flushing it, the complete method would be to take every Rad off, and flush them through with water and then
flush the boiler etc through.
Or you could just try Isolating the boiler and removing the Hot Water heat exchanger (the smaller alloy one below the main heat exchanger) and
flushing that through. And then fill whatever you remove with aditive to get it into the system that way.
Another test for the system would be, does it trip the high limit whilst it is doing the heating as well (if it doesn't give complete preference
to hot water). That way the heat shouldn't back, and it would disprove his theory and prove it to be a dodgy hight limit stat.
A make and model of boiler might be helpful, it may be a common fault. And if its on Microbore pipe it is very probably scaled up!.
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Deckman001
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| posted on 10/11/06 at 10:39 PM |
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Mines a Worcester Bosch Hiflow 400 if it helps 
Jason
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tegwin
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| posted on 11/11/06 at 02:00 AM |
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Go to your local hire store and get a central heating pressure washer thing...cant remeber the name...
Its basically a big tank which you fill with water and chemicals with a massive huge pump sat on it...you take off one radiator or a valve somewhere
in the circuit and connect the washer...
It then forces all of the shite out of the system...takes about 3 hours to get it done properly.....deffinately makes a difference....
Dunc
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