In article ,
dog-man writes:
What's the best stuff to clean a secondary heat exchanger?

Periodically, mine needs a degunge and I use normal bog standard
descaler such as a kettle descaler.

It does work, but I was wondering if there is anything better which is
safe to use?

Furnox DS-3 is the stuff to use. It's Sulphamic (not Sulphuric) Acid,
plus an indicator dye to tell you when it's used up, plus a scent so
you don't drink it. You used to be able to buy it in B&Q, and builders
merchants used to stock it, but the larger tubs have got harder to
find, so I order it from BES.

--
Andrew Gabriel
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