Vaillant heating controls

[adam_no_understand]

Hello,

I'm in an odd situation where by my builder has arranged for a plumber on my behalf as part of his contract which I've paid for. However the plumber has not offered much advice on smart controls. After searching high and low (including asking this forum for advice)

I think I am going to request the following;

Vaillant ecoTEC Plus 620 20kW System Boiler 0010036011

Horizontal Flue Kit

VR 940F Vaillant myVAILLANT Connect Internet Gateway - 0010037346

VRT 51F Vaillant sensoROOM Wireless Thermostat - 0010035748

200L Telford Unvented Tempest Indirect Cylinder

My hope is with this I get;
- An app which controls the thermometer, which load and weather compensates
- A timer for the hot water cylinder
- Manual TRV's for setting room temperatures (other than where thermostat lives)

What I don't know is;
- How the hot water cylinder thermometer is meant to connect to this kit?
- When hot water is drawn it'll need to request heat from the boiler right?
- Does this all get wired directly into the boiler, do I need to think about this when thinking about the boiler controls?
- I assumed the myVAILLANT Connect internet gateway replaced the wiring center... or is that where I'm wrong and I'm missing a critical component?

Any help/advice greatly appreciated

 

[adam_no_understand]

Writing in case this can help others;

Load/Weather compensation requires EBUS, with S and Y plan this is difficult as the valves need 230v and the EBUS uses 24V. For Vaillant they have two wiring centers which can do this.

VR 65 and VR66/2

https://professional.vaillant.co.uk/downloads/product-manuals/vr-66-2/vr-66-installation-instructions-1969891.pdf

"""
The Control Center VR 65 offers a solution to allowVaillant low voltage ‘eBUS’ controls to be used with thetraditional 230 V zone valves and DHW storage cylinderin the English market.Information about the heat required by the cylinder isforwarded by the Control Center VR 65 to the VaillantecoTEC heating appliance. The boiler then decideswhether a hot water request has to be fulfilled andsends a signal to position the 230 V zone valves via theVR 65.In this way, the boiler can store different target temperatures for heating and warm water operation.Standard 230 V components can be integrated into theVaillant eBUS system via the Control Center VR 65.
"""

VR66/2 essentially has 3 modes with "Monozone mode (position 1)" it's literally working as a VR 65

(12) System control is literally the thing attached to the bottom of your Ecotec Plus boiler. It's part of the boiler.

Now this is referencing old models but the new EcoTec Plus boiler I think has a 230V supply on the bottom via a clip so adding a VR 940F Vaillant myVAILLANT Connect Internet Gateway where the VR 921 is in this diagram. I don't need a plug in the wall. I'm also wanting to add a VRT 51F Vaillant sensoROOM Wireless Thermostat on top to get the thermostat in my kitchen/diner, but this just communicates with the VR 940F.

As for using a cylinder thermostat that's explained in (38) at the bottom where by you disconnect the tanks own thermostat controls and then link the Thermostat to CYL in the VR66. The reason to do this is so that it modulates to hit the desired tank temperature rather than just being "on/off"

I've sent an email to Vaillant in the hope they explain if this is possible, given in my setup I've listed using VR 940F instead of VR921

TLDR - you need a wiring center for S/Y plan as it controls EBUS (24V) and also the actuator valves of the CH/HW (230V). You can achieve modulation for CH while having a different target temperature for your HW.