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softened water in sealed pressurised system?

Postby chris_on_tour2002 » Sun Mar 08, 2009 11:04 pm

i installed a water softener last year. finally gotten round to draining down my sealed, unvented system (also brand new last year) and refilled with lovely soft water, no limescale. great - or so i thought.

having done it i've now noticed that (some) softener manufacturers explicitly state that unvented pressurised systems should not be run with water from the softener.

anybody know why? i'm guessing it's to do with boiler components. should i drain down again and refill once again with hard water?

and what happens if you install an unvented system in a naturally soft water area? should one add the minerals to encourage limescale?
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Postby htg engineer » Mon Mar 09, 2009 5:19 pm

I think it will be more beneficial than a problem.

'Naturally soft waters of low alkalinity have a tendency to increase the corrosion of metals used in boilers. This has led to the misconception that artificially softened water is corrosive and should not be used in domestic boilers and central heating systems under any circumstances. In fact, softening has been shown to be beneficial to most system metals when small amounts of dissolved heavy metal ions that are present in the water are removed by the softening process.'

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Postby chris_on_tour2002 » Mon Mar 09, 2009 5:45 pm

thanks for that htg - as i was hoping.

thank goodness i don't have to drain down again!
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