Vaillant VR33 (with Nest) and VR66

[asoffe]

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.

 

[Deleted member 120897]

I don’t believe Vaillant supports opentherm, only ebus which I believe is their equivalent.

 

[asoffe]

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

 

[theozaurus]

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.

 

[asoffe]

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!

 

[ShaunCorbs]

Where are you connecting the ot off the nest to ?

 

[asoffe]

To the OT connections on the VR33 board

 

[asoffe]

If you change from switch 230v to ot you need to put the link back into the 24v connection on the main board too

 

[theozaurus]

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.

 

[asoffe]

I've been considering ebusd and associated interface board for boiler metric monitoring but haven't done it yet.

 

[theozaurus]

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.

 

[asoffe]

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.

 

[asoffe]

With the NTC and Nest HW set to OT, the nest also controls the cylinder target temp as well as schedule.

 

[asoffe]

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

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Cylinder no temp demand

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[boxer01]

If you change from switch 230v to ot you need to put the link back into the 24v connection on the main board too

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.

 

[asoffe]

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.

 

[boxer01]

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.

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.

 

[asoffe]

Yes as per Google's article here: True Radiant - Google Nest Help - https://support.google.com/googlenest/answer/9250165#zippy=%2Clearn-about-radiators-and-radiant-heating%2Chow-true-radiant-works%2Ctrue-radiant-settings-and-opentherm-enabled-boilers
Its the same "learning" of how long things take that I'm guessing is related to how it works out which temperatures to set the flow.
In my experience it also takes a week or two to work out timings and temps.

 

[boxer01]

Interesting reading looks like I need to enable true radiant for boiler to modulate

 

[RGInstaller]

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

 

[SamThor]

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

 

[boxer01]

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

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.

 

[SamThor]

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.

Thanks for confirming I’m going to order the vr33 👍🏻

 

[RGInstaller]

Just doing this today. Just checking nothing connects the boiler to the vr66?

Are the nests connected to it?

 

[RGInstaller]

Connect the bus from boiler to vr66?

 

[Mcalm01]

Thanks for confirming I’m going to order the vr33 👍🏻

I'm interested to find out where to order a VR33 from. I searched around and could not find any supplier here. They mostly come from NL but could only find one who had stock but they stopped shipping to the UK.

 

[RGInstaller]

 I'm interested to find out where to order a VR33 from. I searched around and could not find any supplier here. They mostly come from NL but could only find one who had stock but they stopped shipping to the UK.

Mine was from a Dutch company but they don't have stock.

 

[Mcalm01]

Mine was from a Dutch company but they don't have stock.

Thank you for your reply. I will keep on searching around.

 

[Mcalm01]

Thank you for your reply. I will keep on searching around.

cvonderdelenhartog.nl has received VR33 supplies. I just ordered one unit.

 

[RGInstaller]

cvonderdelenhartog.nl has received VR33 supplies. I just ordered one unit.

That's where I got it from. Works great

 

[Mcalm01]

I posted the message to let other folks know that they have new stocks.

I will be back for assistance in getting it to work on my EcoFit Pure 415 boiler with PDHW.

 

[Sam Thorn]

Just doing this today. Just checking nothing connects the boiler to the vr66?

Are the nests connected to it?

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]

I ordered it from cvonderdelenhartog.nl too. Sorry I've not seen the recent messages for some reason. The wiring is quite straightforward. This website has useful info on the installation, including pictures, of the VR33 (Vaillant gasketel moduleren opentherm VR33 printplaat - installatie? - https://www.dailybits.be/item/vaillant-gasketel-moduleren-met-opentherm-via-vr33-printplaatje/)

 

[Mcalm01]

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.

 

[bwel]

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 ?

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[ShaunCorbs]

You can’t have more than one opentherm device sorry

 

[Registered Gas Man]

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.

 

[magician2905]

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​

 

[Plum47]

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

 

[SamThor]

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

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

 

[nick_p]

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

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

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

 

[Plum47]

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

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?

 

[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. 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)​

 

[gmartine]

Plumbing: Vaillant Ecotec system boiler with VR66 and Opentherm (Nest)

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...

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