NEST + OpenTherm/eBUS interface

[caosmar]

Hi there folks!

I'm wondering to buy the eBUS/OpenTherm Interface to allow my Saunier Duval boiler (Bulex, Valliant,...) to modulate with Nest Thermostat v3.
As much of you can guess, my boiler is not compatible with OpenTherm but eBUS.... 😖

So I have many options:

• Buy another boiler....(💸)
• Sell Nest and buy TADO...(😭)
• Try my luck installing this interface.....(🍀)

My boiler schema is:
(yes, I'm from Spain and the schema is only in spanish, sorry guys....😓)

Any ideas?


Thanks in advance.

 

[Harvest Fields]

Option 4 buy a vaillant ebus smart thermostat

 

[ShaunCorbs]

Be careful with open therm as there are a few different versions and some things won’t talk to eg the boiler

 

[Brambles]

If the interface link you refer to is ( Ebus to Open Therm) is a Vaillant V33 link module, then that works reasonably well.

 

[caosmar]

Option 4 buy a vaillant ebus smart thermostat

Sorry mate, not an option. Nest costed nearly 250 gbp, I've to make it works.
[automerge]1603378044[/automerge]

Be careful with open therm as there are a few different versions and some things won’t talk to eg the boiler

Oooops.....I didn't know about that. Thanks for the advice.
[automerge]1603378371[/automerge]

If the interface link you refer to is ( Ebus to Open Therm) is a Vaillant V33 link module, then that works reasonably well.

I think the V33 link module is pretty similar with the one I referred, but I'm not sure where to plug in.

My boiler board, on X32 has already "something" connected (it's a bit embarrassing speak with that plumbing terms, sorry), it's a temperature sensor? IDK

 

[Brambles]

The schematic that you have posted does not look as if it is for the PCB you have shown in your picture.

You mentioned X32. That does not need to be touched. Strange things can happen if you power the PCB with X32 or X40 removed.

For your PCB you need to ensure that the 24V RT is bridged and that the eBUS socket is unbridged.

The VR33 will slot into X31. The VR33 board itself has a slot on the left hand side.

Your OT bridge will plug into the VR33 plug via a 2 core wire.

Before the OT bridge is wired up check to see if the boiler recognises the VR33 board and is able to fire up the boiler. If not, the boiler control needs resetting.

I don’t know of any other way of getting a Vaillant boiler to operate with Open Therm other than through a VR33 module.

If others do please jump in.

 

[caosmar]

At last, we finally did it.

Our Saunier Duval PCB now is compatible with both Open Therm and eBUS protocol thanks to this module.

Check this out:
Interface eBus a Opentherm - NEST loves SAUNIER DUVAL


Thanks to all for your advices.

 

[prablych]

Hi,

How is it going? Does it work well? Any flaws detected?
Can you also tell wich S.Duval boiler model you are using?

Thanks

 

[iperezu]

I did it!
I finally made my boiler Saunier Duval isofast condens 35 work with my thermostat Nest 3rd gen using the interface 0020092426 Opentherm module advanced AWB.
I just followed the video on the link in a post above and disconnected the radio receiver of the default wireless thermostat (Exacontrol e7r) provided by the vendor.
Thnx!