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Burger
Vaillant Ecotec plus 824: heating has been coming on when in the off position.
So customer hadn’t another engineer (works for same firm) out and said a part needed changing (diverter), so didn’t question it. Changed diverter valve, carried out 26.9 put into p1 to gas rate, exited programme and boiler fired up for ch, however it was off on the time clock and stat, and no radiator symbol in display window. Reset boiler all good, and couldn’t recreate the fault, it behaved as it should (s.30). What I don’t want happening I should the same thing where it just comes on, especially this weather.
External clock: Horstmann 425 coronet
External room stat: Honeywell wireless - didn’t get model
Checked voltage across pin 4 on pcb when the boiler fired up for ch, no voltage. Tested with room stat on, 230v. Checked pcb voltage getting 5v. I’m currently suspecting the external clock but couldn't get to backplate as it wouldn’t come off.
Sorry for long post and couldn’t find any that related, as usual any thoughts welcome and thanks in advance.
Chris.
Edit: should have stated that the clock is set to on 24 hours, but is awaiting over-ride from room stat.
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