Vaillant VR33 (with Nest) and VR66

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Discuss Vaillant VR33 (with Nest) and VR66 in the Central Heating Forum area at PlumbersForums.net

asoffe

asoffe

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Does anyone have experience of using a VR33 (for Heating OpenTherm control with Nest) and a VR66 for Hot Water Priority with Vaillant system boilers? I'm specifically using an EcoTec plus 624
I've got a system working with a Nest and VR66 to provide hot water priority and it works well with separate cylinder charge and heating flow temperatures. Currently this is all connected to the Nest using the switched CH and HW controls. I'd like to use the OpenTherm capability of the Nest for the heating but have questions about how the VR33 and VR66 coexist if they can at all. There is no timer or thermostat connected to the VR66. The only control input to the VR66 is the cylinder stat & nest HW switched line.
I'm hoping that the VR33 just behaves like an ebus thermostat and would work alongside the existing setup (with removing the switched CH controls on the boiler) but would love to know if anyone has experience of going into this level of detail.
 
The VR33 Vaillant module converts OpenTherm to eBus in the boiler (unsupported in the UK but should work) but I'm trying to understand if plays nice with a VR66 when fitted and connected to a Nest 3rd Gen
 
I'm looking to do exactly the same thing. I'd like to use OpenTherm controls, but my house has a Vaillant boiler and is plumbed in an S-Plan configuration. I cannot find any controls that will use the OpenTherm protocol and manage the valves directly. My understanding is that the VR66 will allow the boiler itself to control the valves for DHW and CH so that the controls are not directly involved.
From the reading that I've done the VR33 acts as a bridge between eBUS and Opentherm so in theory the boiler will not know the difference between an eBUS controller connected directly, or an Opentherm controller connected via the bridge. There's a fair bit of discussion on the VR33 on the Automated Home forum. On this thread OpenTherm VR33 and Vaillant ecoTEC plus 428 - https://www.automatedhome.co.uk/vbulletin/showthread.php?6396-OpenTherm-VR33-and-Vaillant-ecoTEC-plus-428 someone suggests that the VR33 is 'low priority' and will not work with other eBus controls.
Looking at the specs: https://ebus-wiki.org/lib/exe/fetch.php/ebus/spec_prot_12_v1_3_1_e.pdf and https://ebus-wiki.org/lib/exe/fetch.php/ebus/spec_prot_7_v1_6_1_e.pdf eBus clearly supports multiple devices on the same bus (I guess the clues in the name), so it seems like it 'should' work.
 
So I went ahead and tried it all anyway and it works perfectly. The vr66 provides hot water priority for the boiler and can control the valves for ch and hw. The vr33 allows the nest to control heating and hot water using opentherm! The only other thing I added (which you don't need) was the vr10 ntc sensor for my hot water cylinder so that nest can control the cylinder temp instead of the mechanical thermostat.
Now to fix the one radiator which seems to have sludged up!
 
Where are you connecting the ot off the nest to ?
 
Oh, that's great. You've given me the confidence to do the same setup on my boiler. I've got an Opentherm gateway that I'm hoping to use between the controller and vr33 so that I can log the boiler metrics. Armed with that I'm hoping I can get it tweaked to eek out the most efficiency.
 
Incidentally, are you able to schedule your hot water using the Nest when it's connected on Opentherm or does it work solely on the VR66 switching the system to hot water priority (upping the temp, and controlling the valves) when the nest says there is demand.
 
Yes. I originally set up heating with OT and HW with switched live (HW cylinder stat and switch in Nest linked in series to VR66 cyl stat connection) but then changed the HW to OT when I received my VR10 NTC as well and it controls the schedule. I don't know how it would behave with OT HW control and cyl switched stat.
 
You also get better feedback with the HW via OT. The two images below both show the HW set to on in the schedule but one shows that there is no demand from the cylinder.

Cylinder temp demand
1666959921579.png


Cylinder no temp demand
1666959985055.png
 
asoffe said:
If you change from switch 230v to ot you need to put the link back into the 24v connection on the main board too
Click to expand...
I have installed the vr33 on our vaillant ecotec plus. At first I could not get it to work because I hadn't linked the 24v connection but once this was rectified the boiler works. I have the flow temp set at 65 deg.c but to me the ot is not modulating the boiler very well. The boiler flow is on 65 when heating is on, or off when up to temp the idea of open therm is to ramp boiler down before it reaches set temp. So it doesn't obershoot.there is no in between I was wandering if settings on boiler need to be adjusted to accommodate the vr33 or do I need to link ebus connections on PCB as well as the 24v connections.
 
Are you using a Nest with OT? If so, True Radiant needs to be enabled on the Nest for it to set the flow temp. On the Vaillant you can also see the ebus target temp (D.9 on the EcoTec Plus 624) (flow temperature requested by the Nest) in the settings to see what is being sent. Mine is definitely modulating down. If it has a large temperature difference it will fire at max set temp (75 in my case) and modulate down as it approaches the target room temp (44 at present).
The ebus connections should not be joined to my knowledge.
 
Last edited:
asoffe said:
Are you using a Nest with OT? If so, True Radiant needs to be enabled on the Nest for it to set the flow temp. On the Vaillant you can also see the ebus target temp (D.9 on the EcoTec Plus 624) (flow temperature requested by the Nest) in the settings to see what is being sent. Mine is definitely modulating down. If it has a large temperature difference it will fire at max set temp (75 in my case) and modulate down as it approaches the target room temp (44 at present).
The ebus connections should not be joined to my knowledge.
Click to expand...
Hi thank you for replying yes I am using a nest 3rd gen stat but true radiant is off as the heating was coming on too early especially in the mornings, to achieve 21 at 7am the heating was coming on at 0330 or earlier. so are you saying without the true radiant heat feature the boiler will not modulate down on approaching set temp.
 
I am a heating engineer and wish to thank you both.

I have nest and a Vaillant ecomax but have a ecotec 618 lying on floor of loft, never bothered switching it over as it works and the lack of OT on Vaillant drives me nuts (was thinking of just dumping the free 618). I've now collected the necessary components and your posts here are the best help I've had on piecing the control system together.

I'll report back.

Thanks again
 
This is really interesting thread, are you able to post any pics of your nest wiring into the vr66 board and explain the process a bit further. Any information appreciated, I have a y plan system and I’m considering installing the vr33 board for better modulation with nest
 
SamThor said:
This is really interesting thread, are you able to post any pics of your nest wiring into the vr66 board and explain the process a bit further. Any information appreciated, I have a y plan system and I’m considering installing the vr33 board for better modulation with nest
Click to expand...
I cannot send pics cos I have no vr66 but the vr33 is plug and play plugs into xr31 or xr32 depending on your boiler. The two OT wires from heat link go onto OT connections on vr33 and make sure 24volt connections in boiler have a link in. Also on the nest stat make sure you have enabled OT and not on/off switching.
 
boxer01 said:
I cannot send pics cos I have no vr66 but the vr33 is plug and play plugs into xr31 or xr32 depending on your boiler. The two OT wires from heat link go onto OT connections on vr33 and make sure 24volt connections in boiler have a link in. Also on the nest stat make sure you have enabled OT and not on/off switching.
Click to expand...
Thanks for confirming I’m going to order the vr33 👍🏻
 
RGInstaller said:
Just doing this today. Just checking nothing connects the boiler to the vr66?

Are the nests connected to it?
Click to expand...

I’m a bit confused by this too. Is the nest connected to the open term only and the vr66 still controls hw and heating under command from nest as putting in the vr33 changes ebus to opentherm? Why is the vr66 still required if nest can modulate over opentherm? Any help appreciated 👍🏻
 
asoffe said:
Thank you for the info. I'll be in touch when I am ready to set it all up. I will be getting my old Potterton Supriema replaced with a Ecofit Pure 415 and my aim is to configure an identical setup like what you have managed to do with a VR10 NTC to keep the HW Cylinder topped up when the storage water temp drops below a set threshold. I have a single 3-port valve (s-plan) and just need to figure out which wires I need to connect to the VR66. If you have a pic as you know the saying goes. it will speak louder than words.
Click to expand...
 
Has anybody managed to use the VR33 with Two zones i.e two Nests on OpenTherm ?

eg image below.
Nest 1 - Central Heading (CH) Ground Floor
Nest 2 - Central Heating (CH) Upper Floor AND Hot Water (HW)

If so, do you simply link the two Nests Opentherms (OT) together, like dives on a multiple master Bus ?
Certainly eBus connections can work like this, but I'm not sure about Nests and the VR33 Opentherm

Ideally, I would like to have
  • Nest 1 with a lower Target Temp (50) and Lower kWh, that better suits Underfloor Central Heating.
  • Nest 2 with a High Temp (75) for the HW Cylinder Charging and the Upper Floor Central Heating radiators.

If so, would you still need to use the Opentherm alongside the VR66/65 for Hot Water Priority ?

Screenshot 2023-04-20 at 09.16.45.jpg
 
Not strictly correct. You cannot have Mike opentherm zones with Nest. Nest is all flashsy but lacks substance...

EvoHome can handle multiple opentherm zones as can EPH controls.
 
Do either of these help anyone?

How to install & wire Nest thermostat for dual / multi zone system with radiators and UFH​


How to install Nest thermostat (UK) on an S plan - system with hot water cylinder​

 
Hi All, can anybody advise what is the correct set-up for SYSTEM Vaillant boilers?

Currently I have the boiler with a junction box for the valves and water cylinder and a classic room thermostat (Salus, On/Off type).

I have the vr33 module as well as a tado unit. Where do I go from there? Do I simply remove the old thermostat, plug the the vr33 on the PCB, and wire tado to the 2-pin connector of the vr33?

Or instead, does the vr33 need to be connected to the junction box somehow?

Thanks
 
Plum47 said:
Hi All, can anybody advise what is the correct set-up for SYSTEM Vaillant boilers?

Currently I have the boiler with a junction box for the valves and water cylinder and a classic room thermostat (Salus, On/Off type).

I have the vr33 module as well as a tado unit. Where do I go from there? Do I simply remove the old thermostat, plug the the vr33 on the PCB, and wire tado to the 2-pin connector of the vr33?

Or instead, does the vr33 need to be connected to the junction box somehow?

Thanks
Click to expand...
I’ve just completed this install . Run a new 2 core cable from boiler to nest heatlink. Install vr33 believe it connects into x32 port . Connect the new wire to vr33 and nest heatlink, remove old thermostat. Setup nest as open therm
 
Plum47 said:
Hi All, can anybody advise what is the correct set-up for SYSTEM Vaillant boilers?
Click to expand...

SamThor said:
I’ve just completed this install . Run a new 2 core cable from boiler to nest heatlink. Install vr33 believe it connects into x32 port . Connect the new wire to vr33 and nest heatlink, remove old thermostat. Setup nest as open therm
Click to expand...

This is an excellent question. How do you get Nest and VR33 to work together on a SYSTEM boiler, WITHOUT a VR65/VR66. Everyone else on this thread seems to describe how they use both VR33 and VR65 /VR66 Control Centre.

Here is my experience having done exactly as SamThor describes (and also bridged the RT24 and disconnected the RT240 live):

The CH is working with fine with modulation, but the boiler is not firing when there is DHW demand from the thermostat, neither is it applying the DHW temperature when both are running. My CW and DHW valves are still being controlled by the Nest thermostat and the DHW boost/charge signal is being sent via OpenTherm (D025 shows “Ext eBus signal: Cylinder charging: On” when there is hot water demand via Nest and off when there is no demand). However, the boiler refuses to fire up, presumably because it is not connected to VR65/VR66 to know the actual status of the valve/cylinder thermostat?

Has anyone managed to install VR33 and an Opentherm thermostat on a system boiler without a Vaillant Control Center? Thanks
 
nick_p said:
This is an excellent question. How do you get Nest and VR33 to work together on a SYSTEM boiler, WITHOUT a VR65/VR66. Everyone else on this thread seems to describe how they use both VR33 and VR65 /VR66 Control Centre.

Here is my experience having done exactly as SamThor describes (and also bridged the RT24 and disconnected the RT240 live):

The CH is working with fine with modulation, but the boiler is not firing when there is DHW demand from the thermostat, neither is it applying the DHW temperature when both are running. My CW and DHW valves are still being controlled by the Nest thermostat and the DHW boost/charge signal is being sent via OpenTherm (D025 shows “Ext eBus signal: Cylinder charging: On” when there is hot water demand via Nest and off when there is no demand). However, the boiler refuses to fire up, presumably because it is not connected to VR65/VR66 to know the actual status of the valve/cylinder thermostat?

Has anyone managed to install VR33 and an Opentherm thermostat on a system boiler without a Vaillant Control Center? Thanks
Click to expand...

I'd be happy to try things out Nick, I've ordered the module and a TADO smart thermostat. I also have a spare vr65, and currently wired via classic junction box.

The thing that puzzles me is how did the other guys manage to get it working even with the vr65.

From I understand what they did is:

1. Plug the vr33 on the PCB
2. run 2 core wire between their smart thermostat (Nest) and the vr33
3. run eBus between PCB and vr65
4. Connect the motorised valves to the vr65

If they manage to get control of DHW with this set-up, does it mean that when you select DHW with your phone, connect to the smart thermostat (Nest here), the smart thermostat will then communicate to the PCB via the vr33, which then sends a message through the PCB out to the eBus, which is then sent via eBus cable to the vr65, which will then tell the DHW valve to open and let hot water fill the tank?

That would also mean that the boiler now knows that DHW is ON and needs to stop modulating and heat more so the flow temp is above 60 degrees?
 
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. The wiring in logic is exactly as you say above Plum47.
I have written about all the steps here in a clean thread (I can't link, you have to search for it)

Vaillant Ecotec system boiler with VR66 and Opentherm (Nest)​

 
nick_p said:
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. The wiring in logic is exactly as you say above Plum47.
I have written about all the steps here in a clean thread (I can't link, you have to search for it)

Vaillant Ecotec system boiler with VR66 and Opentherm (Nest)​

Click to expand...
Hi, Do I need any of this if I am using Valliant ecotec pro combi boiler with VR33 OpenTherm and Nest ?
 
Daw____ said:
Hi, sorry to jump in. Do you mean the 24V RT connection bridge?
I am also thinking to connect Vr33 openTherm module to my Vailliant ecotec pro24 to work with Nest gen3.
Click to expand...
Hi Daw

I think what @asoffe said is that if you remove the on/off type 230v control, and switch to a low voltage digital (eBus) connection, you should have a bridge on the "24v = RT" block on the PCB, which is a white block. Then you will connect your + and - on the eBus block if you want to use eBus, which is a orange / reddish block.

Hi, Do I need any of this if I am using Valliant ecotec pro combi boiler with VR33 OpenTherm and Nest ?
Click to expand...

Tell us a bit more about what you currently have and what you are trying to do so we can try to help.
 
I'm setting up the VR66 and have installed the VR33.

Please can someone confirm how to wire 2 Nest stats for the 2 zone system I have. Do I put the VR33 OT wires to both NEST boxes?

Is two zone control possible with this setup. It's currently S plan with Unvented cylinder.

What version of VR66 did you use, there's VR66\2 which is most recent which they say has updated software.
 
JamesBaby said:
I'm setting up the VR66 and have installed the VR33.

Please can someone confirm how to wire 2 Nest stats for the 2 zone system I have. Do I put the VR33 OT wires to both NEST boxes?

Is two zone control possible with this setup. It's currently S plan with Unvented cylinder.

What version of VR66 did you use, there's VR66\2 which is most recent which they say has updated software.
Click to expand...

You can’t wire two nests in opentherm only one stat in the system
 
Really interesting thread - thanks for sharing experience/knowledge. My house was renovated ~10 years ago.
System comprises Vaillant 624 EcoPlus system boiler with 3 CH zones (rads up, rads down + UFH (HeatMiser UF3) ) plus HW in an unvented Main 210L tank); The UFH has 4 zones with 4 wall stats (as an aside, I think this is unnecessary now as the areas are mostly open plan so a single stat would suffice).
"Interestingly" the two rad zones share a common stat - I think this is fundamentally flawed but rather than fix it I'm looking to do a wholesale upgrade to get more efficient by using modulation + decent controls.

I've ordered a VR33 (FYI you need to create an account to get UK shipping - a guest can only do collect)
As per the excellent info, I was going to get the VR66* but am I right in thinking this will do HW plus one CH zone only?
If so the confusingly named VR61 seems to be twin CH zones + HW capable - could be used instead. is that correct? (I'll probably merge the rads up /down but TBD . I guess my final question is similar to James in that how would this (OT) work with two stats?

Thanks
 
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