In message , Tim Lamb
writes
In message ,
newshound writes
On 09/03/2018 19:52, Bob Minchin wrote:
Tim Lamb wrote:
So the gas fitter came to call....

and expressed concern about using an ion exchange (salt) water softener
with a thermal store. Corrosion of heat extract coil due to salt content
in treated mains supply.

Google hasn't found much apart from now discounted worries about boiler
heat exchangers.

Gledhill technical advice dept. were only accepting voice messages
(poets day?)

Anyone come across this. In 25 years it has failed to penetrate either
the side walls or the coil in our hot tank.


purely on the basis of gut feel that if the level of salt in the
water cannot be tasted then I cant really credit that corrosion can
be risk.
Never had a water softener and hated showering in places where they
have been fitted so no practical experience to offer.
Can you get thermal stores with stainless steel heat exchangers.
Might open up a whole load of electrolytic problems? Mine is all
copper and I don't recall being offered a choice of materials when I
had it custom made.

Untastable levels of chloride can be sufficient to cause stress
corrosion cracking in certain stainless steel welds (but IIRC only
above about 50 deg C).

I believe the thermal store coils are finned copper. The planned boiler
has stainless steel inox radial heat exchanger and the manufacturer
encourages using softened water in the closed circuit system.

I'll see what Gledhill technical have to say tomorrow and report back:-)

Gledhill technical seemed happy for an ion exchange softener to be used
for DHW. They pushed their polyphosphate offering but did not reject the
alternative.

I have since asked a similar question of my softener supplier who was
confident this is a red herring.


--
Tim Lamb