Vaillant Boilers, Nest and Opentherm

[Jerry]

Good evening you marvellous lot!

So, i have a client that wants the Vaillant pure combi boiler (my go to rear flued boiler), with a Nest controller.

As far as I can tell, there is no easy way of making these 2 work easily together. The only way I can find is to use the following thingy:

Vaillant VR33 OpenTherm Module

I am also led to believe that this will invalidate the warranty, EVEN THOUGH ITS MADE BY VAILLANT!!!!!

Does anyone have a new or up to date info on this?

Cheers,
J

 

[ShaunCorbs]

Why not you have

Lne and then your call for heating once you remove the 24v link

?

 

[Jerry]

Hi Shaun,
Sorry, I was not clear and you are right.
I want to make it work with the low voltage OpenTherm connections.
J

 

[ShaunCorbs]

Hi Shaun,
Sorry, I was not clear and you are right.
I want to make it work with the low voltage OpenTherm connections.
J

Any reason why and normally if you want to go down that route it’s vaillant only controls via the ebus

 

[Brambles]

I may just have bad luck, but I find the Valliant Open Therm interface ( and you can only really use the Valliant interface) lacklustre in its performance when compared to other manufacturers.

 

[Scott_D]

Tado does ebus I believe

 

[Jerry]

Any reason why and normally if you want to go down that route it’s vaillant only controls via the ebus

Why? Because it (should) be more economical in the long run

 

[ShaunCorbs]

Why? Because it (should) be more economical in the long run

TBH it won’t do that much better off with weather comp sensor outside

 

[Burger]

This any good Jerry?

Learn about OpenTherm and what Nest thermostats can do with it - Google Nest Help

Also:

 

[Jerry]

Cheers Gents!
I am only looking for a way to link a nest (with opentherm) to a Vaillant combi boiler. I think it can be done with the dohickery in my first post but i was wondering if anyone knew different.
I usually fit boilers that are Opentherm ready (like Ideal, Intergas, Viessmann etc) and this is not my first choice boiler.

In regards to what ShaunCorbs said, I would disagree BUT am very willing to be educated. I thought the point of OpenTherm with a combi was that it could modulate the boiler as it sees fit PLUS take into account weather compensation PLUS the Nest learns your habits and can switch off when you(r phone) leaves the house. All of these would/should/hope add up to more energy savings.

 

[ShaunCorbs]

they dont do/ make an open therm boiler

either 240 controls or there no in-between

only way you can do it is with an outdoor sensor and use 240 switching with the nest

 

[Jerry]

Hi Shaun,
Yes and No.
They make an OpenTherm module for the European Market but its kind of an unknown here in the UK.
I think you are right though. Far too much faffing around.
J

 

[ShaunCorbs]

Hi Shaun,
Yes and No.
They make an OpenTherm module for the European Market but its kind of an unknown here in the UK.
I think you are right though. Far too much faffing around.
J

how much do you want to bet even if you get one it wont be the same software / you would need to flash it to make it work (to the eu software)

and then if anything goes wrong your on the hook for a new boiler and controls

 

[Jerry]

how much do you want to bet even if you get one it wont be the same software / you would need to flash it to make it work (to the eu software)

100%

 

[Scott_D]

they dont do/ make an open therm boiler

either 240 controls or there no in-between

only way you can do it is with an outdoor sensor and use 240 switching with the nest

I don’t think Vaillant have a simple outside sensor for weather comp

 

[ShaunCorbs]

I don’t think Vaillant have a simple outside sensor for weather comp

https://www.amazon.co.uk/Vaillant-693-External-Temperature-Sensor/dp/B008H4NNB4

dont ask me how to wire one of them in tho dont have a clue just know vaillants are a pita to do

 

[EvilDrPorkChop]

A number of people on the Evohome forums have bought the VR33 from Europe and had it fitted. From their experiences I believe it works with UK boilers with no issues with Honeywells Opentherm receiver on EvoHome.

However I have to agree, I don't see much energy savings since the lower flow temperatures require a system design to handle that. Retro fitting it to an existing system that hasn't been designed for it I can't really see any energy savings. TPI and smart thermostats IMO work pretty well at maintaining set points without the need to reducing flow temperatures.

 

[Harvest Fields]

Let’s fit a boiler with a 10 year warranty and void it by fitting one of these.

 

[AMGasServices]

If you’ve got a nest connected via 240v as suggested by Shaun (I think) it will be pretty efficient as your customer uses it the more efficient and economical it will become. Nest will look into local weather and adjust everything accordingly.

Finally it’ll be boilerplus compliant.

 

[Harvest Fields]

If you’ve got a nest connected via 240v as suggested by Shaun (I think) it will be pretty efficient as your customer uses it the more efficient and economical it will become. Nest will look into local weather and adjust everything accordingly.

Finally it’ll be boilerplus compliant.

Hive does the same if not using opentherm

 

[Jerry]

Customer is going for an Ideal Vogue Max! That fixes that problem.

Thanks for all the input gents.

J

 

[Harvest Fields]

Customer is going for an Ideal Vogue Max! That fixes that problem.

Thanks for all the input gents.

J

Good luck with that

 

[Viacheslav]

You can connect Vaillant boiler and Nest (3rd Gen) using OpenTherm via VR33 module (personally I made it with AtmoTEC Pro combi boiler). VR33 was made for Belgium and the Netherlands, but you can use it anywhere. Consider that Vaillant VR33 costs bit more than absolutely same modules made under other trade marks like AWB or Saunier Duval. So you can find the solution.

 

[EvilDrPorkChop]

You can connect Vaillant boiler and Nest (3rd Gen) using OpenTherm via VR33 module (personally I made it with AtmoTEC Pro combi boiler). VR33 was made for Belgium and the Netherlands, but you can use it anywhere. Consider that Vaillant VR33 costs bit more than absolutely same modules made under other trade marks like AWB or Saunier Duval. So you can find the solution.

But doing so voids your warranty here in the UK

 

[tonyramponi]

Related to this thread, I have a Valliant ecotek Pro with a VRT350 controller which I believe modulates the bolier. I've acquired an unwanted Nest E thermostat but not sure if I want to use it unless I get my hands on a VR33.

I've had a slightly bonkers idea - What happens if I connect the nest to the on/off boiler switching but leave the VRT350 connected and set to a fixed temperature?

If the VRT350 still works but is overridden by the switching of the nest I would theoretically have a system which modulates the boiler in normal use but could be switched off using the nests geo location facility. A set-back temperature could be maintained using old school on/off switching.

I guess I wouldn't get the full benefit of modulating control since the outsIide temperature wouldn't be factored in when determining the demand in winter.

Is this a dumb Idea or worth a try?

I have a 1930's semi and i'm forever fiddling with the timer programs in order to get the house to warm up in time for when we get up. I guess I should stop being tight and get Vsmart controller or a VR33. Am I correct in thinking the Vsmart can do outside temperature compensation using internet temperature data?

Thanks,

Tony.

 

[ShaunCorbs]

Won’t work as you can’t use ebus and on off at the same time

 

[tonyramponi]

Thanks, so in other words the ebus has priority over both the 24v and 230v thermostat switches?

The only reason I was thinking it might be the other way round was the need to install the jumper wires on the other terminals when using the ebus. I.e Why do you need the jumper wires?

I was thinking that using the nest to replace a jumper wire would allow it to override the ebus until the nest demanded heat. When the nest is demanding the jumper wire would be back in place and the ebus would back in control.

I could quite easily make something to disconnect the ebus when the nest is in set-back mode and switch it back in when the opposite is true but this probably too much of a dirty hack with unknown consequences. My original idea doesn't feel quite so dirty if the ebus is just ignored when a jumper is effectively removed.

 

[Jerry]

Put an hourly rate (£/hr) on your time. Then estimate the amount of time you guess you would spend trying this, before giving up and/or breaking something. Then add on the additional time you would spend being annoyed if you had managed to get the system partially working but not exactly how you would want it.

When you have this total, compare it to how much a plug-and-play unit would cost. Then go from there.

Don't forget to add the time you have spent on the forums.

And not a single mention of warranties etc