Opentherm R-BUS

[zomo]

Opentherm gateway from nodo shop is compatible with R-Bus?

[hvxl]

As I understand it, R-Bus is a De Dietrich proprietary bus. They have different versions of their thermostat for R-Bus and Opentherm, which suggest they are different protocols, not just different names for the same thing. As the name suggests, the OTGW is designed for the Opentherm protocol. It doesn't handle any other protocol.

[rvdbreemen]

Just found out today that the R-bus is an "interpretation" of a canbus. So yes, it proprietary. But if you use the Remeha eTwist gateway to OpenTherm, you will be able to decode the OpenTherm traffic again.

This is the gateway from Remeha:
https://www.warmteservice.nl/Verwarming ... p/14256360

Regards,
Robert

[Tonga1968]

Hello Zemo,

the documentation of my Giersch "Giegastar Plus" shows the following (in german):

„Der Heizkessel ist standardmäßig mit einem R-bus-Anschluss
ausgestattet. Ein modulierender (OpenTherm) Thermostat kann ohne
weitere Modifikation angeschlossen werden. Außerdem ist der Heizkessel
für OpenTherm Smart Power geeignet.“

Means in english:
“The boiler is standard with an R-bus connection
fitted. A modulating (OpenTherm) thermostat can do without
further modification can be connected. Also is the boiler
suitable for OpenTherm Smart Power.“

I have connected my OT Gateway to the R-bus, and it's working.
But I don't know, if the “R-bus” is a registered trademark or if anybody can use this notation, so maybe, the protocol behind a so named bus is not standardised.

Regards,
Christoph

[rvdbreemen]

That’s exactly the same as in the manual of the Elga Ace. The controller hardware in the boiler is probably the same and coming from the BDR Group. Giersch and Remeha are both part of that group I think.

So the Boilers can actually be used with the OpenTherm Gateway. Just make sure your Thermostat is also OpenTherm and not like mine R-bus. Then you need an R-bus to OpenTherm converter, which does exist for a friendly price of 125 euros or so

Regards
Robert

[Bartb]

This thread is a bit old already, but I have a question which is related.

I've just had a Remeha zTerra Ace installed.
An eTwist thermostat is connected directly, without any separate gateway. The "Ace" version supports this.

Yesterday I ordered my OTGW.

Question: Would I need an extra gateway with this setup, if I want to get the OTGW to work?

The Remeha has a R-bus which says it supports both the proprietary R-Bus protocol, as well as OpenTherm (+ any On/Off thermostat).
The manual says it recognizes which thermostat is connected.
But... Can it do both simultaneously in parallel or will it actually disable OpenTherm if an eTwist is connected?

Anyone any experience?

Hoping for the best
Bart.

[hvxl]

That won't work, unfortunately. Most likely each device will prevent the other from working if you connect them in parallel.

The OTGW can talk to the Tzerra Ace using the Opentherm protocol. You can use that setup without a thermostat. But if you want to have a thermostat in addition to the OTGW, you have to connect it to the OTGW. And the OTGW can only handle Opentherm (and On/Off). So, you'll need an Opentherm thermostat, or add a converter if the thermostat uses a different protocol.

[Bartb]

Clear. Thanks. I do still have my original OT thermostat, so Ill check the OTGW on how to connect it.