Vaillant Vr33 open therm module question

[boxer01]

Hello Everyone, I decided to obtain a vr33 module for my Vaillant eco tec plus system boiler. I have a nest 3rd gen thermostat and installation was pretty straight forward. When boiler is calling for heat boiler is not firing up although led on vr33 is flashing and it seems to be communicating with the ebus system and I'm getting no error messages. The question is if anyone out there has any experience with this module why is the boiler not firing up do I need to change any settings on boiler, do I need to bridge any connections ie the ebus or rt connections. I understand the vr33 is not available in this country and vaillant do not recommend but from what I've read quite a few people have installed it and it works well.

 

[bwel]

Hi there,
Did you find a solution for this ?
I have a multi zone system. I'm thinking of trying to change one Nest (HW and CH Radiators Upper Floor) from Switched Heat demand to Opentherm control, but retain the second Nest (Ground Under Floor Heating) staying on switched Head Demand control.
My objective in this is to run the 1st nest with open therm modulation and internet weather compensation of the Nest, whist the second Switched Heat Demand Nest woud operate against a Target Flow Temp of 50 degrees (set in the boiler) and possibly Range Rated to 15kw, rather than the Max 30kw of the boiler.

 

[nick_p]

I managed to get Nest to communicate with my Ecotec Plus 624 system boiler via the VR33 (with modulation) and work for the CH. The wiring was as in the manual, I basically just needed to wire in the OT contacts, plug in the VR33 at X31, bridge the RT24 contacts and remove the RT240 (live) from the S plan box.
However, as soon as I plugged in the VR33 the boiler stopped firing up for DHW - regardless of Nest settings and status. I suspect it is down to the absence of a VR65 / VR66 control centre (£90), which is where the boiler presumably looks for to ensure there is actual demand from the cylinder thermostat, and that the valve is open.
Let me know if any of you got it to work with a DHW external cylinder. I'll be posting this question on other forums as well and will report back.

 

[nick_p]

I was able to get the Opentherm, Nest and DHW priority to work once I also installed the VR66, which effectively eliminated the S plan system.
I have written about all the steps here:

Vaillant Ecotec system boiler with VR66 and Opentherm (Nest)

Hi everyone, Just wanted to share my experience with "upgrading" an S plan setup to Opentherm and Vaillant Control Center (VR66). There are a few threads on a few different forums but I wanted to share a full write-up with all the steps needed, benefits and costs. Overall, I fully recommend...

www.plumbersforums.net