Thema "Betreff: Reading diagnostics values of a system with a Vitocal 150-A + EM-HB1" in Getting started programming with the Viessmann API

Reading diagnostics values of a system with a Vitocal 150-A + EM-HB1

fabiospark — Fri, 14 Aug 2026 17:54:57 GMT

Hello everybody, Fabio from Italy here.

We have just finished the installation of a Vitocal 150-A modular + puffer 6 connections 300lt for heating and cooling a house with fan coils. There was already a Vitodens 200 (gas) installed in the 2012, with two stations: the fan coil one mentioned above and a floor panels one. In the future we could end up having to add a ceiling panels new station.

I managed to read and download some of the diagnostic values of the system through python scripts via the API and then dump the values in a csv file. With an Excel workbook I import the values from the csv and show them on a grafic to monitor (and learn) how the various temperatures moves and the pumps and compressor switch on and off when the system in on.

For example, here you can see the monitoring of today time from 12:16 to 18:14.

(due to the limitations of the API calls I can only monitor about 6 hours as I'm asking for 10 different values every 2 minutes)

The only temperature I couldn't read is the return from the fan coils line, to check how much thermal exchange I'm having, to see if it's already optimal or if I can improve it, maybe slowing up or down the fan speed or, if it will be possible, modify the flow rate of the pump.

The system seems not to have a specific input for such a temp sensor but maybe you know better than me and my engineer and will tell me thet it's there...

Thinking it is not, and to the fact that an EM-HB1 module was installed to enable/disable the old Vitodens 200 (old bus protocol), I'd like to ask if would it be possible to use the TS2 sensor port on the EM-HB1 that by now has an NTC sensor wired to but it's not in use. Could I use this sensor to read the temperature of the return of the fan coil line? Will I have to ask my engineer to enable it or I can do it in the service menu on board the 150-A as I've been given the password?
When enabled, maybe as "hydraulic equilibrator" one, will influence the behaviour of the system?

Thank you for listening.

Betreff: Reading diagnostics values of a system with a Vitocal 150-A + EM-HB1

qwert089 — Fri, 14 Aug 2026 19:33:05 GMT

>>(due to the limitations of the API calls I can only monitor about 6 hours

when connecting to the 150-A by CAN Bus, you have no such limitations

https://community.viessmann.de/t5/Konnektivitaet/CAN-Bus-Home-Automation-E3-Generation-lokal-und-kostenlos/td-p/356066

https://github.com/open3e/open3e

Betreff: Reading diagnostics values of a system with a Vitocal 150-A + EM-HB1

fabiospark — Sun, 16 Aug 2026 14:53:15 GMT

Thank you qwert089, I will have a look at your solution when I have completed what I'm trying to do and see it working via the API. For now it is not that important to be able to query more frequently than 20/30 times per hour.

In the meantime, if you know the answers to my questions, feel free to reply to them and to this new one:

- I see that the temperature of the puffer - and consequently of the fan coil line, varies from 7.5 to 13.5°C:

does anybody know for sure which parameter I have to touch in the service o r in the user menus to make it narrower? I think that the right range should be between 10 to 12°C.
I changed the 3616.0 parameter (Cooling buffer hysteresis activation) from 20 to 10, leaving the 3616.1 (Cooling buffer hysteresis deactivation) to 20 but nothing changed.

Would more knowledgeable people tell me the number of all the parameters involved in cooling when there is a buffer (or puffer) between the heat pump and a fan coil station, please?

Is there any free documentation about that that I can download?
As I said, I've been give the service menu pw and I've been allowed to make changes there.

Thank you.

Betreff: Reading diagnostics values of a system with a Vitocal 150-A + EM-HB1

qwert089 — Sun, 16 Aug 2026 19:08:11 GMT

may be connect with the owner, of the thread you already found.

https://community.viessmann.de/t5/Waermepumpe-Hybridsysteme/Update-04-2026-Standardwerte-und-Dokumentation-zu-den-neuen/m-p/626451

this document should also be availabe in italien language, ask your dealer.

https://static.viessmann-climatesolutions.com/resources/technical_documents/DE/de/VSA/6200041VSA00009_1.pdf?#pagemode=bookmarks&zoom=page-fit&view=Fit