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.

 

[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