Vaillant Ambisense R920 unit/Ecotec Plus 831 installation problem

25 Nov 2006
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United Kingdom

I bought a Vaillant Ambisense Starter pack (three TRVs and control unit) for my EcotecPlus boiler. I've connected the boiler's BUS terminals and the R920 controller's BUS terminals and , set up the Vaillant VRC700 app. There's an internet connection but when I open up the app I get 'Installation not compatible - no compatible control could be identified '. I've done the re-start etc but am getting nowhere.
Any ideas? I used 2 of the 4 core heat resistant cable that was used by my previous Siemens RF controller, might that be the problem?

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I've swapped the cable for 0.75mm2 2core multi-strand but it's still not working. I've reversed polarity. I've deleted and reinstalled the app. Still the same message. Please help!
Hoping today's weather might mean a Vaillant/Ambisense expert abandons outdoor plans and goes online to rescue floundering diynotters... :)
Post a photo of wiring please, and any other controls.
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Hi Chris - there's a photo in my first post - the boiler's electric board, the controller's connection and the app message - can you see it? (It's there when I'm logged in but disappears when I'm not)
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Reactions: CBW

No, I can’t see anything, it’s not on your profile media either.
Have you also got a VRC700 controller plugged in somewhere?

No, I can’t see anything, it’s not on your profile media either.

My media settings were set to 'owner only' so I've changed it to 'everyone'. Maybe that's the reason. It's in the Vaillant Ecotec Plus 831 boiler folder. Thanks
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Reactions: CBW
That’ll be why it’s not working. You’ll need a VRC700 as well.
Setup seems ok, perhaps it actually isn’t compatible? Unless it’s as per @Cal10 and you need the additional controller?
Yeah the Ambisense controls are meant to be used on conjunction with either a VRC700 or a sensocomfort hence the ‘no compatible control’ error.
Ah ok. Shame Vaillant didn't tell me that when they advised me to buy the Starter pack, I thought including everything to needed to get started was the point of it! o_O Thank you for pointing me in the right direction!

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