Three times in the last three or four months I have had leakage from the auto air valve from our 24CDi (about 7-8 years old). It has always happened just after a prolonged DHW demand ( i.e running a bath) when there is no CH demand. The leak seems to be slightly damp hot air - I cant be sure but don’t think it is water vapour or steam. No liquid water leaks out. The leak lasts for maybe 60-90 seconds and only leads to small pressure drop (i.e. once it cools down pressure is just under 1 bar – normally 1 bar cold). When hot it is normally about 1.5 Bar – don’t knows if it goes above this just before the aav blows as I haven’t seen it happen (usually blowing for 30-40 seconds before I get there to see what is going on !). The system has always needed a small top-up each year – say from 0.9 bar to 1.0 bar. We are in a hard water area and it had been a bit noisy and was treated with Sentinel silencer about a year ago and has been fine since. No air in rads.
I suspected that it was overheating because the overrun function wasn’t working but have watched the boiler 5 or 6 times when filling a bath and fan and pump do exactly what they are supposed to after the end of a DHW demand (at least they do when I’m watching!!!) ..
Anybody got any ideas ?
Also it sometimes locks-out at start of a demand - following the diagnostic flowchart leads to changing the control board (£200 +). Are these problems likely to be related ? is repair of the board possible ?
Thanks
trevor
I suspected that it was overheating because the overrun function wasn’t working but have watched the boiler 5 or 6 times when filling a bath and fan and pump do exactly what they are supposed to after the end of a DHW demand (at least they do when I’m watching!!!) ..
Anybody got any ideas ?
Also it sometimes locks-out at start of a demand - following the diagnostic flowchart leads to changing the control board (£200 +). Are these problems likely to be related ? is repair of the board possible ?
Thanks
trevor
