Controlling Viessmann Vitodens Gas Heater Boilers locally (new models 100-W, 200-W, ... after 2018)

I fully agree. My comment wasn’t meant in a cynical way.
Just that, for tinkerers, the Optolink interface was more accessible.

1 Like

Indeed, the optolink is also great that you keep full functionality of the built-in controller and just monitor/adjust parameters that you want. That is probably not possible neither via opentherm or other local controls.

Anyway thinking ahead, are there any other heaters that have a good local integration or e.g. KNX integration that does not cost a fortune?

1 Like

Have a Viessmann Vitodens 050 here. Have been able to set max boiler temperature without difficulty.
Arthur Rump hasn’t made any updates to his code for two years, so I’ve been using this fork - GitHub - FreeBear-nc/esphome-opentherm: Create your own smart modulating thermostat using the OpenTherm component for ESPHome - A little more active, and there is a sample yaml for the Vitodens 050W.

Great job Adorobis.
Q1: can you send an instantaneous ON request to the heater from HA now ? Dont’ see this option in your pics.Or in another term, if you feel too cold, how can you rapidly tell the heater to turn ON ? via the party function ?

Q2: the room temp. (RT) sensor where it is located in your case (I suppose not directly to the heater but somewhere far away in a different room )? can you use this RT sensor + set bar in HA as a thermostat (i.e. the heater is heating until the set RT is reached–> 22°C in your pic ?)

Q3: can you program the RT on different days as it can be done on the heater onboard control ?

thanks a lot, Alex

Q1: there is no such feature, to just start heating. If the boiler is in the reduced temp mode (e.g. at night) you can turn on party mode and it will start heating if the room temperature is below the set one. One option could be to set the party mode target temperature at higher value so it would start heating.
Q2: RT is in the room controller (Vitotrol 300) which I have here. It duplicates most of the controls from the controller on the boiler (but not all of them). And yes, it acts as a thermostat and turns off heating on the circuit that it is assigned to (in case you have more than one circuit)
Q3: Yes - the programming is exactly the same as in the onboard controller.

1 Like

thanks !
to Q2: setting RT via HA is updating to Vitotrol300 display too ? Which Vitotrol300 model do you have, the old A type wired via BUS-KM or the new E wireless Vitotrol300 E ?

Q4: I was wondering why viessmann heaters came with an onboard chronothermostat if one usually needs an external (chrono)thermostat to control them? from the manual I see the onboard menu allows programming one or more heating circuits based on a RT input (or external sensor). So, would it be possible to control the heater through a RT probe directly connected to the heater control unit (without purchasing an external thermostat)?

Yes, this one. My heater is 16 years old and has the KM-Bus

Well, you don’t need the room controller, the on board one is enough, especially if you have floor heating and properly set heating curve. Actually since a few years now I never reach the temp set on my room controller.

1 Like

Can you please share details on how you connected the USB Optolink Adpater to the ESP32? Thanks.

You can’t use the USB optolink adapter unfortunately. It has a bult in serial chip and I couldn’t find a way to use it with ESP32. So I’ve used components as described on this page:

The Problem with handmade Adapters is that you always end up with spare resistors and leds and other components.
The official optolink adapter is rather expensive and you need to be lucky to get a used one for cheap.

Not a big problem as they are very cheap