Vaillant DHW Heat Exchanger query

[trukkakhan]

Hi all,
My friends boiler is a Vaillant Turbomax Pro 28/2E - installed 2001.
The DHW performance is quite low - only properly hot if the hot water tap is turned down low.
He is not working at the moment so over a £100 plus labour for a new heat exchanger is not possible.
Can someone advise what metal this heat exchanger is made of and what could be used to "descale " it ?
On a side issue if a cleaner like Fernox is circulated through the CH system does any of it go through the DHW heat exchanger ? If not does it mean a hot water tap has to be left on ? ( It will fill the bath for a soak anyway ! )

 

[Whitespirit66]

I whipped out the DHW hex in my father's Turbomax earlier this year. Cleaned it as described in the thread link below. Performed as a new hex when it went back in, as it does to this day.

//www.diynot.com/forums/plumbing/how-to-clean-a-plate-heat-exchanger.356402/#2688253