Nest Opentherm wiring

[erion]

I need some help wiring nest Opentherm on vaillant boiler. It's currently wired to 2 zonevalves to split the ground floor (ugh) and first floor radiators. I have attached some images to help.

Thanks

 

[ShaunCorbs]

As you have two zones can’t use open therm on the existing set up better off using an outdoor sensor eg weather comp

 

[king of pipes]

🤣Or 2 nests ? Maybe expensive but it's only money.

 

[ShaunCorbs]

🤣Or 2 nests ? Maybe expensive but it's only money.

don’t think you can use them in both open therm only one

 

[Brambles]

The starting point with complex control systems is to set out what you want to achieve. From there, design the system, cost it, see if it is viable. If so implement it.

With Open-therm, of which I like the concept, you are taking a lot of the boiler manufacture’s control knowledge and expertise and placing it in the hands of a third party. Particularly with Vaillant boilers, they are not designed (configured) to be fully open to “Open Therm” compliance. Consequently, in my experience, they do not perform in “open therm” as effectively as they do with a Vaillant control system.

Nest is good valve, but it is very limited in its flexibility to effectively control more complex systems

 

[Scott_D]

Vaillant doesn’t support opentherm as far as I know
It used ebus

 

[Brambles]

With Vaillant, you need to interface through the Vaillant VR33 module to Ebus for a “limited” Open Therm connection. It (VR33) is around £100, available in the UK, but is cheaper to purchase in Europe (circa Euro 60).

I do however agree with Scott, Vaillant do their very best to discourage you from controlling their boilers through third party full Open Therm. Honeywell Evotherm in Open therm mode, works reasonably well through the VR33.

In reality, you can fully control any boiler in the Open Therm protocol through a Raspberry Pi - the cost is just how many hours it takes you!! That’s a hobby for those who need to get out more, not a business.

 

[erion]

Thanks for the replies

 

[boxer01]

With Vaillant, you need to interface through the Vaillant VR33 module to Ebus for a “limited” Open Therm connection. It (VR33) is around £100, available in the UK, but is cheaper to purchase in Europe (circa Euro 60).

I do however agree with Scott, Vaillant do their very best to discourage you from controlling their boilers through third party full Open Therm. Honeywell Evotherm in Open therm mode, works reasonably well through the VR33.

In reality, you can fully control any boiler in the Open Therm protocol through a Raspberry Pi - the cost is just how many hours it takes you!! That’s a hobby for those who need to get out more, not a business.

Hi I have just got my vr33 open therm module and will fit soon. At the moment my boiler is controlled by a next 3rd gen stat wired into 240v rt connections, there is no bridge in the 24v, if anyone has fitted the vr33 please can they tell me if I need to bridge both the 240v rt and the low voltage 24v connection or just the 240v rt where my nest is connected to at present.
My boiler is a vaillant ecotec plus vu446/5.

 

[Brambles]

The VR33 is connected to the PCB by the interface cable. Once connected the VR33 has priority. The bridge connections are superfluous and won’t work.

The software version for the VR33 should be the same as the installed software on the PCB.

Unless there has been a recent change, the VR 33 is not supported by Vailliant UK. Consequently, be careful of fitting the interface unless you are clear on the process it is very easy to unintentionally damage the PCB.

 

[boxer01]

The VR33 is connected to the PCB by the interface cable. Once connected the VR33 has priority. The bridge connections are superfluous and won’t work.

The software version for the VR33 should be the same as the installed software on the PCB.

Unless there has been a recent change, the VR 33 is not supported by Vailliant UK. Consequently, be careful of fitting the interface unless you are clear on the process it is very easy to unintentionally damage the PCB.

So I don't need to bridge any connections.

 

[Brambles]

It won’t make any difference whether or not you bridge the connections, but do check the software versions are aligned.

 

[boxer01]

It won’t make any difference whether or not you bridge the connections, but do check the software versions are aligned.

Ok thankyou

 

[Mcalm01]

Hi I have just got my vr33 open therm module and will fit soon. At the moment my boiler is controlled by a next 3rd gen stat wired into 240v rt connections, there is no bridge in the 24v, if anyone has fitted the vr33 please can they tell me if I need to bridge both the 240v rt and the low voltage 24v connection or just the 240v rt where my nest is connected to at present.
My boiler is a vaillant ecotec plus vu446/5.

Could you please tell me where you got your VR33 module from? I have been searching but no one seems to have any in stock including suppliers in the NL.

 

[Lou]

(Just bumping a few older threads, they will drop off what is new soon)

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