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An Intermittent Ignition Fault on a Vaillant EcoTEC Plus 824 Combi Boiler

Postby STRAWCLUTCHER » Sun Mar 25, 2018 3:14 pm

Hello — I'm new to this forum, and joined in hopes of finding a cure for a problem that is driving me barmy. Five-plus years ago, we had part-central heating installed, for the first time. The boiler is a Vaillant EcoTEC Plus 824 (a combi), and there are only three rads in the house (one in the bathroom, one in the hall and one in the kitchen). Since this is a modulating boiler, the fewness of the rads is OK — the installer told me that he had adjusted the boiler to take this into account, so as not to burn the boiler out. Much of the time, everything is fine — the heating is good and the hot water is hot etc. However, from time to time (at first, soon after the installation), it would be weeks between the occasions when the ignition failed. We found this out (in Summer) when we turned on the hot tap, and it would run cold. I would go to the boiler (in a closet with a door on an outside wall of the house) and simply switch off the boiler, then, after waiting for about thirty seconds, switch it on again. After this, it would go for weeks, with no trouble at all. About three weeks ago (early March 2018), this fault started to occur much more frequently (sometimes, three times in one day, but mostly once a day or once in two or three days). Twice, Gas-Safe registered engineers have looked at/tinkered with at the boiler, but cannot find out the cause of the fault. I cannot afford to keep calling out engineers, as, being pensioners, our means are quite limited and we have already spent what we could afford (but with no cure for the boiler). The governors of the gas meter have been replaced, the water and gas pressure are said to be good, there is nothing wrong with the flue (so I am told), and the ignition electrode has been cleaned. Since the engineers came, I notice that, whereas, previously, I could just switch the boiler off, then on again, and it would be OK for a long time, now, when it re-starts, an error message appears (F28/F29) on the display, and there is a need to press the fault-clearing button, before it will "load" as it ought to. The only exception to this is if it is switched off at a time when it is running OK. Then, by simply pressing the ON switch, it loads in the normal way.

Is there anything anyone can suggest, to have this boiler put right? Also, there is another question: When the installer adjusted the boiler to take account of the fewness of the radiators, was this adjustment something that I may have negated, when I pressed the ON button and held it in for a second? (This is the Vaillant-approved way for the householder to reset the boiler.) Or was that initial adjustment something that only an engineer could reverse, with his access to more arcane menu items? (You will see why I am asking this question — I don't really know what a "re-set" may involve.)

Any helpful replies would be greatly appreciated, and thanks in advance.
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