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Central heating power flush

Postby bhardwaj » Fri Apr 25, 2008 6:01 am

In Oct 2006 I had a new Combi boiler installed. To comply with warranty I had the system power flushed. All but 3 radiators were replaced. The system was clean and efficient and runs perfectly. Within 6 months faults started to appear in the boiler. The overflow leaked and water had to be refilled, small amounts only. A sensor replaced. Now the divertor valve leaked. One of the new radiators had leaked from a valve showing strong signs of rust. The engineer who came to fix the divertor found that rubber piston inside had disintegrated and the water in the system contaminated. The water has rusty colour and strong smell.It darkens to deep orange on exposure to air. I have tried to call the people who did the flush but they are not very helpfull or can't say why the problem had occurred. They suggested another flush. Can I have your advise please as to the cause of the problem. It appears to me that the radiators have rust. This has occurred since the power flush. Do I need to add inhibitors to stop the problem and can it be done without the flush. Could there be another cause of this problem? Previously I had no problem with my old combi for 12 years. Never had power flush. This time new condensing boiler,almost new radiators with no sludge except rusty water.
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Postby htg engineer » Fri Apr 25, 2008 1:26 pm

After the powerflush, the system should have been filled and flushed again if any chemicals were used during the flushing process.

Also after the powerflush inhibitors should have been added to the system, was this done (i bet not) ?

have you drained the system since the new boiler and radiators were installed ? if so then the inhibitor should have been renewed. There should be a sticker on the boiler to say what date the inhibitor was added.

You have to replace the inhibitor everytime you drain the system.

Hope this helps
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