Hi can someone lend me some advice. I have the above names boiler for some years now and have a problem. Boiler fires on hot water demand but rapidly goes up in Temp and then cuts out. The water temp goes up so high and then cuts and same. Turns off and on. Pump changed as was the pressure sensor and vessel charged but still happens. We have also removed the Hydro block and cleaned/flushed it with appropriate acid and flushed but still same problem. Its like the boiler overheats and cuts off and on again.
Hot water heat exchanger furred up, identical problem with my Valliant 824, had new one fitted, everything perfect now. Does the hot water some times run cold. Strange posting this in Painters section.
There is also a filter in the cold water inlet that might need cleaning. One other thing, I tried descaling HW plate exchanger, it doesn't work very well, so had to fit new HW plate exhanger.
Hi Thanks.. sorry I have fat fingers and hit Painters instead lool. Plate Exchanger was cleaned with acid. Where is the Hot Water Exchanger? The big one up top?
The one left side at top is for CH heating. Secondary DHW heat exchanger is the one in the middle no 11 in the link https://www.plumbase.co.uk/vaillant-ecotec-plus-831-10000225-3549599/explodedviews Better linky. https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiYg-yS5pnPAhXMCsAKHa3BCGcQFgh2MAA&url=https://www.vaillant.co.uk/downloads/ecotec-plus-spare-parts-manual-261420.pdf&usg=AFQjCNFJBBTB6QobTI5XhcEgGqPUuAhu6A
Aha.. this was removed and cleaned with acid and flushed and refitted but still issue is still present.. ? Any other ideas?
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