Cozzer,
Interesting to hear of your experience as I have the identical boiler fitted. As a former electronics engineer I find it frustrating that a small fault in a circuit board renders it inoperative and silly money to replace.
Yes, XTiffy...me too.
The plumber admitted it could've been literally a dry solder joint - that's how bloody ludicrous it is. When I checked it turned out to be just over 6 years old - a bit older than I remembered - but what I also found amazing was the 12 month only warranty when originally fitted. It looks as though the dreaded "7 year life expectancy for white goods" is being borne out.
That said, it replaced the ancient Glow-worm something-or-other that we inherited when we purchased the place. We realised it was on death row from day one, but it (and we!) struggled on manfully for a few years until it became stupid, and was replaced by the (same) plumber.
We've had a few problems with it in the 6 years - nothing particularly desperate, mainly the F22 error which seems to be the No.1 error with the Eco-Tec range, and this model in particular. It's usually solved by topping up the water - you'll probably know how to light up the display screen, and let enough water in so it rests between the min and max lines. Another tip he gave us on day one was not to bother with the clock/timer - well-known for being inaccurate apparently, so we control ours from the thermostat downstairs.
Anyway, we got up on Thursday/Friday/whichever to find no display at all. Changed the 3A fuse in the power switch, and momentarily the screen lit to reveal the F22 error....opened the taps to bring the water pressure up, but no... the display reverted to black and the usual noises stopped. Seeing it had "fired", I figured the fuse again, so tried another. Same thing....
The rest you know.
Why both PCBs required? Dunno.
I sat in the bathroom and watched. It took him longer to unclip the PCBs than to fit the new ones. The few cables that have to be attached resemble the old connectors in a desktop computer of a few years ago. It's obvious from the cable length where they fit, and would be difficult (impossibe?) to connect wrongly. The two Vaillant manuals he left are illustrated like a child's book, albeit written in German and English. The second manual guides you through various diagnostics....and that was it.
The old boards were placed in the electro bags the replacements came in, and away....to be checked for the dodgy solder joint maybe, and sold as "refurbished"?! Who knows!
I now wait for the next F22, which usually takes every 7/8 days to appear, but of course our event diary has been thrown out of kilter!