Extension kit unpredictacble after boiler PCB replaced

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frozentoes
frozentoes ✭
in General Questions & Topics

Hoping for an easy fix here. My boiler broke down on Thursday, with the fan and PCB replaced today. So the boiler and extension kit were powered off for around 40 hours (after the fault was established). While the boiler now is capable of coming to life, Tado doesn't seem to trigger it when it needs it. I can see in the app all of my radiators and hot water calling for heat, but the boiler is in standby mode. If I stare intently at the extension kit, sometimes the boiler will spring into action, but mostly it does nothing. I can hear the relay clicking in the extension kit just before the boiler fires, but given there's multiple TRVs and a smart thermostat calling for action, I'd expect the extension kit to be snapping it's fingers and the boiler to be complying much earlier.

Needless to say the bridge has been restarted, the extension kit restarted, tado support spoken to. I've not found a reliable way yet to trigger the boiler, but the last way that worked was to turn up the temp on the smart thermostat. Although again, that could have just been a coincidence.

LED on extension kit is "pulsing/breathing".

Any ideas on how to fix this? I'm at a bit of a loss on how to make sure I have heating during the night, other than to take the batteries out of the smart thermostat and hope the extension kit operates in dumb mode.

cheers!

Answers

  • jelockwood
    jelockwood ✭✭✭
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    @frozentoes

    You don't specify the make of boiler you have. One possible cause is if you have a Vaillant boiler and the logic board change changed the controller module from a VR65 module to a VR66 module then this would make it incompatible with Tado for eBus control.

    To clarify, Tado 'understands' the eBus protocol spoken by a VR65 Vaillent module but does not understand the eBus protocol spoken by the new VR65 module.

    Ideally Tado would add support for the VR66 but last I heard they had still not done this. Alternatives would be to reconfigure to using 'call for heat' instead of eBus, getting another VR65 module, or getting a VR33 module to translate the eBus commands to OpenTherm commands.

    Note: The VR33 module is an official Vaillant part but intended for use in the Netherlands and fitting one in the UK would invalidate a warranty even though it is a genuine part.

    Obviously if you have a different brand none of the above would apply.

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