Opentherm gateway/thermostat with full integration for Home Assistant

I answered you on GitHub. The list contains boilers that have been tested by other users. If a boiler is not on the list, it does not mean that the firmware will not work with it.

However, this Bosch boiler most likely has an EMS bus, not an Opentherm.

Hi LazyDev,

You can add to the tested boilers list the Ideal Vogue Max 32 as that is my boiler and this project is working very well with it.

I do have a question now though due to a scenario that came up today. In conducting some fault finding on my house electrics HA was shut down for a period while the house electrics were turned off. Once the power was restored the boiler fired up its heating and started to reach its set maximum temperature. I realised fairly quickly that this was because since I am using the automation to obtain the internal house temperature from a wall mounted BLE sensor, it had no reference point until HA was up and running. Once it was then all was back to normal.

The adapter I am using (from DIYLess) does have the DS18B20 installed so is there a way for the gateway to use this sensor in the event communication with HA is lost for any reason (power loss or fault on HA)? My only concern is that if one was away for a period and then the gateway lost communication to HA the heating would be running constantly at its maximum.

Thanks for the info, added. The emergency mode has probably been activated. The settings are on the “Settings” page, section “Emergency mode settings”.
You can connect a BLE sensor to your ESP. But it will not be possible to use BLE/MQTT/API and DS18B20 at the same time.

In most cases, Equitherm works acceptably even without an indoor temperature sensor (if the connection with MQTT is lost). But for this, you need to use the DS18B20/BLE to get the outdoor temperature.

Ok understand and thanks for the reply.

Thanks a million. I relied on the vendor who claimed opentherm compatibility. Thanks to your hint, I dug deeper and figured out similar solutions for EMS Bus.

Is it possible to run this firmware on the Opentherm gateway board from Nodoshop?

No, this is board for the OTGW (tclcode)

Alright thanks. I was wondering because I already had an OTGW board from nodoshop laying around and they both seem to use an D1 mini.

The board from nodoshop uses ESP only for communication via Wi-Fi, and for communication with the boiler PIC16 with firmware of the OTGW from tclcode.
If you want to try this firmware, I advise you to think about buying a board from DIYless with ESP32.

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We have a Remeha Tzerra Ace boiler connected to a Remeha Elga Ace heat pump. This has been controlled via OpenTherm by a Google Nest v3 thermostat for several years. Since we want to move away from Google, I bought the Diyless Opentherm Thermostat, installed firmware 1.4 on it, and then integrated it into Home Assistant. In HA, everything seems to function fine. However, when I connected the Diyless Thermostat to the Remeha, the thermostat was not recognized as such. None of the functions seem to work. Both the DHW and heating do not work. The boiler falls back into a standard mode. The question now is: is it known that Diyless with firmware 1.4 does not work with this Remeha, or am I perhaps doing something wrong?

Hi,
Perhaps you are using the wrong GPIO’s in the opentherm settings? I should draw your attention to the fact that, for example, pin D5 is not GPIO 5. You can find the pinout of your board in Google.

Thank you, i did something wrong. The Remeha works great now with OT!

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