Energy IQ, opentherm
Hi,
I live in Scotland, I have a v2 system, my current boiler is a Viessmann Vitodens 050-w B0KA, which was installed in January 2024, replaced an Alpha Intec. The installer connected the v2 extension kit using relay mode, the heat flow was setup to 60 C and the hot water to 60 C. After the installation I haven't changed the boiler model type in the tado app, I only did it yesterday. I have smart meters both for gas and electricity and I have reconciled the gas consumption with the invoices and what I can see that in Q1 2024 I cannot see any significant difference, Energy IQ shows a little bit lower consumption compared to the invoice, but I assume the hot water consumption would explain the difference. As my house has good insulation (EPC B), I have reduced the heating flow to 40 C and the hot water flow to 40 C (no water tank, it's a combi boiler) in the summer and using these settings currently. I have checked Energy IQ consumption in October 2024 and the app shows above 900 KW consumption but based on the smart meter reading only 650 KW was invoiced. My first question why is there a huge difference?
I'm thinking about changing the boiler wiring to opentherm as the extension kit and the boiler both supports that, compared to the current heating flow and hot water settings would it result further energy savings with the modulation or the current setup will result better energy savings? I have read in the forum that for opentherm I should increase the heating flow to 60 C or above, that's why I'm asking the question. I have to call the engineer to do that, but before I do that I'd like to ask your opinion.
KR
Ferenc
Comments
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According to the Tado guide this boiler only operates in relay mode, not Opentherm mode. However this guide Installation and service.PDF suggests otherwise, pages 23 and 24 refer. If this boiler offers an Opentherm capacity, a digital control mechanism which enables the boiler to operate more efficiently. Connection to that, is via the motherboard connector X12 - a remote control connector D.
You need to check
- Please clarify, by contacting Tado support, through the App, whether your existing extension kit is compatible with Opentherm and whether your specific boiler model supports Opentherm.
- Double check inside your boiler and look for the X12 connectors. Tado may be wrong in assuming that your boiler only runs in RELAY mode.
Now here you may need to make a decision. If this is a combie boiler (which that guide suggests it is), unless you are deploying a hot water tank, you should only need to use a wired Smart thermostat to talk to the boiler. However Tado support should advise you specifically on what products should be used with this boiler.
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An Extension Kit (serial number BU…, the predecessor to the Wireless Receiver) always supports Opentherm. For the Wireless Receiver we have 2 versions, the UK one with 2 relays and no bus and the EU one with 1 relay + bus. The Extension Kit only came in one version for all markets and has both; 2 relays + bus. But, it is harder to setup/install as it has no test and config buttons.
Anyway, my database says about 050-w B0KA:
This boiler has an internal DHW tank and interprets the Opentherm connection from tado° as DHW Comfort mode. It will start heating regularly to keep the internal DHW tank on temperature.
To prevent this RELAY should be used.
So yes it supports Opentherm, but it interprets Opentherm signals a bit different than what you'd want. At least according to my database.
With Opentherm you can set both domestic hot water (DHW) and radiator water flow temperature in the app. No need for an engineer there. It will probably be a bit more efficient for heating. However, for this specific boiler, given the quote above, it might be a tad inefficient for domestic hot water.
One thing to note as well: The Extension Kit needs its own power plug when it is using Opentherm. You can use a generic one.
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@Ferencs. @Rob responded in record time! This leaves one remaining unknown.
- How was your extension kit wired into the boiler. Was it through the X12 port, or via the basic thermostat port?
If the former, then, may be worthwhikle contacting Tado Support through the app, to:
- confirm that your wiring is correct
- the configuration at the Tado's backend reflects your needs.
Come back if you need more help.
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Hi,
Thank you for your help, I don't know how the boiler was wired to tado, the engineer did it in January 2024 when they installed the boiler. Currently I cannot control hot water through tado in relay mode, only using the viesmann vicare app. In the UK we cannot touch the wiring of the boiler, only gas safe engineers can modify that.
I have read the issues about DHW, viessmann engineers can override that according to the community posts remotely with some kind of software modification.
Can I expect any more energy saving with opentherm if the DHW is solved?
KR
Ferenc
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Can I expect any more energy saving with opentherm if the DHW is solved?
In theory, yes. But I don't know if it will be significant. That is really hard to answer and not really tado specific. That's a question I'd shoot back at Viessmann, specifically for this type of boiler. To what extent Opentherm saves energy compared to a relay connection.
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@Ferencs . If you have access to a mobile phone, could you look through the installation guide and, if you are comfortable, try and identify where the cables have been placed, take photos and post them here? Posting photos via a windows or apple laptop browser works here. Doing it by phone doesnt.
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Hi,
Please find above the cable connection, could you please advise how to modify those to opentherm? If I understand correctly, from the extension kit side, N and L should remain and the other should be wired to + and - on the right, but from the boiler side I'm not sure.
KR
Ferenc
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Hello again. Thank you for the photos. Unfortunately the one from the boiler, i tried to look for the connections, could not see a connection to X12. If you can, would you push for support through the app to give you three things:
1. An assessment of what in your existing kit would work with the boiler in a digital control state. It is possible that your extension kit won't work with this boiler, they must tell you that.
2. A full set of instructions to the changes needed to wire and fit the kit needed to operate that boiler in digital mode.
3. Whether there is an option to exchange your existing extension kit for the version that does work.
If they say that something, such as the extension kit needs to be replaced with one that is compatible, you have two options:
a) Buy a brand new item.
b) look on Ebay for a version that is compatible.
It is likely that you will need to get an electrician to make the changes for you, once you have the instructions. However come here first when you have all the facts. We may be able to help.
@Rob can you study this one please?0 -
The Extension Kit here is the older type device. It will work with Opentherm. If this one won't work with this boiler using Opentherm, then no tado device will. In that sense, the tado hardware device is not a bottle neck. My earlier remark about how the boiler "
interprets the Opentherm connection" has nothing to do with this specific Extension Kit, but more with how this boiler deals with Opentherm in general or at least Opentherm as applied by tado regardless of tado hardware.I have 4 points to make it work:
- Opentherm wiring
I found the image above in my documentation. It was listed to be specific to the 050-w B0KA. Here you see at the right side the X12 connector, which if you follow the lines is connected to '3', which is for the OT (Opentherm) thermostat. That is what you are looking for at the boiler.
The + and - of the boiler (X12 → 3 → OT) should go the + and - of the Extension Kit
2. power wiring of the Extension Kit
The current power wiring to the Extension Kit will also need to be redone. What is currently wired to N and L (and 1 and 4) will go to the boiler for your switched live relay connection. This will have to be redone, and is typically replaced by something like the following generic cable (to N and L). That is what we generally recommended as a power source for these devices, for Opentherm. If you want to do it via the boiler and without that cable, great and possible, but only if you know what you're doing.
3. Opentherm configuration of the Extension Kit.
This can be done via the installer menu on the thermostat, it can be done automatically in the app by generating installation instructions for the EK (select an old Opentherm wireless receiver to replace; example: Honeywell R8810A1018) and it can also be done via support. Whatever you prefer.
4. Opentherm setting on the boiler
My documentation states about this Viessmann boiler:
Operation mode "C.7" needs to be set as Opentherm = 14
This is a setting on the boiler itself. I assume your boiler manual will tell you something similar. Please do double check.
Please do note that you need all 4 points above to make it work. Adjusting just one, two or three will result in a non functional system.
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Thank you for your help, I called my engineer and will show the instructions to him and get back to you if any questions pop up.0
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If your engineer needs help, also check this manual for installers, specific to the Extension Kit using Opentherm (and other digital connections). Note that there is phone number for professional installers only on the last page. Especially useful if he struggles with the configuration.
Do note it is the most busy time of the year right now. But, the installer line should be reachable.
To others who read this: different manuals for installers can be found here. Note that you can scroll down to find more. We recommend these manuals for pro installers only. For normal users, the installation instructions that you can generate in the app are much more user friendly.
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Thank you @Rob. Constructive.
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Hi,
Could you please check again the photos? Because I'm not sure that the mains (220v) is wired from the boiler to the extension kit, in the white cable there are only two cables, not four so it seems to me that the extension kit is not receiving the 220v from the boiler, so only the relay cables should be connected to the opentherm inputs at both end, no independent power supply is needed.
KR
Ferenc0 -
@Ferencs2 Sorry am a bit slow today. These are my initial reflections - please bear with me:
- Normally the extension kit in relay mode would have
- A standard mains wiring source (with a real permanent live, neutral and earth). It could parasite off the mains supply to boiler.
- Another wire which contains the incoming switched live feed from the boiler, wired to COM - and it can be drawn off the permanent live in (a) above. When the extension kit is in relay mode, all it does (when it is asked to provide heat) is connect that incoming switched live with the outgoing switched live - wired to NO (Normally Open).
- So in the conversion to Opentherm, you'll need two cables. One for the mains feed to the extension box. Another for the opentherm. @Rob was right. You'll need to find a local power source for that extension kit, unless you feel you can run another cable back to the boiler.
- If you do have the capacity to fit another cable back to the boiler, its best place is to be fitted to PLUG NO 40 by the motherboard, which handles the incoming power from the mains to the boiler. Hence, when the boiler switch is turned on, the extension kit also gets its power. When turned off, both turn off.
- If not, best to reassign the old cable that had a relay role to Openthem.
- Hopefully we're together on the logic this far.
- Next steps suggested:
- Confirm that the white cable does actually go to the extension box. A multimeter would help.
- Ensure that the extension box has a new source of mains power
- Reassign the old cable connector that was on L, N and pin 4, following @Rob's above instructions.
- Apply the rest of Rob's steps.
Have I missed something?
0 - Normally the extension kit in relay mode would have
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Thank you, to give you more clarification, currently there are two cables from the box to the boiler, a white and a black one, the black is the power cable the white is the "communication" cable (sorry I'm not an expert).
The box is wired as the picture below:
As you can see, from there are 3 batches of cable coming from the wall: one is the power source that is coming from the main switch of the box, the other is connected with the tado extension kit ports 1-4, this is connected to the white cable, the third one is the power cable that is going back to tado N,L and shared with the boiler (black cable) as well (if I understood correctly). Could you please check if the power source of the tado needs to be changed or not? I have tried to call my service company, but they don't care since months, don't recommend the change from relay to opentherm (however there is an article at viesmann uk homepage detailing the benefits of the change), I wrote to Viesmann requesting a service but they haven't replied since a week.
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I have successfully connected the extension kit to the boiler using openthern, necessary steps:
1. Connected the white cable batch to the opentherm ports of the boiler
2. Moved the cables in the extension kit from 1-4 to opentherm ports
3. Tado power source was already independent, so no changes were necessary
4. Reconfigured tado with tado pro app, changed the connection to opentherm.
5. It was also necessary to set the max flow temperature to 60 C in tado pro setup check in the boiler part
6 recommissioned the boiler to change settings to opentherm using viguide app
7 called Viessmann to remotely setup an override on tado's hot water control, so eco mode is available again on the boiler
Thank you for the help. The wiring manual is still not prepared by tado, the colleague assumed looking at the photo that there's no opentherm ports in the boiler.0 -
@Ferencs2 Well done on getting this far. Would you mind explaining in more detail what Viessmann had to do with your boiler to override the Tado hot water control, and how that presented as a worthwhile change? Somewhere along this year it is possible another Viessman user will face the same hurdle.
@Emcee @Ferencs2's case does give cause for the support team to pause and consider the lessons to be learned.
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Reina wrote me an email about the missing opentherm connectors in the boiler and I have replied to her.
Regarding Viesmann I have read in this forum that Viesmann can remotely contact to the boiler if wifi connection was setup and modify the hot water control, so it can be managed in the vicare app. In opentherm mode the boiler constantly prepares hot water with 60c and eco mode cannot be selected from vicare. After the modification I had setup the boiler to eco mode and the hot water temperature to 40c as this is a combi boiler.
KR
Ferenc0 -
@Ferencs2 . Thank you. Will remember0
