# Heavy descale - HX boiler only



## destiny (Jun 4, 2015)

So... managed to get the pretty stuck element out of the Cherub boiler to find a rather poor sight of scale. Nothing unexpected, but a decent build up from hard London water (I presume).

Since it's completely isolated I can get it filled up well and descale and flush however I want.

What would you say the usual ratio in such a case could be before getting into trouble? For a normal flush through I was using 50g citric for every 2L of water.

Internally, the boiler is covered with a film of scale, and in some places there is quite a bit more of it..

Cheers!


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## espressotechno (Apr 11, 2011)

Phosphoric acid, 1:5 dilution, is more effective. The brand name is "Phos".


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## jimbojohn55 (Jan 15, 2016)

Tartaric acid, (apparently) gentler on the seals - whatever used, you may need a couple of goes to get it clean as the lime scale neutralises the acid - ive found that using recently boiled (not boiling) water to be more effective, not sure why.


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## destiny (Jun 4, 2015)

@espressotechno, did you mean something like this?


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## espressotechno (Apr 11, 2011)

Yes, that's the stuff. Most catering/janitorial supply companies stock it.


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