I do not trust my Bosch thermostats

Configuration Zigbee
1

I have three Bosch Room Thermostat II units (RBSH-RTH0-ZB-EU) installed in my living room, bathroom, and bedroom. A friend installed them for me since I’m not really a hardware guy.

I live in a fairly new basement apartment (for rent). I expected it to be on the colder side, especially in winter, but it’s consistently warm. The temperature sits around 22 °C all the time. Even when I open the windows and the temperature drops for a bit (to about 20 °C), it always climbs back to ~22 °C afterwards.

The thermostats are connected via Zigbee and integrated into Home Assistant. I’m not using a Bosch Smarthome Controller because I wanted a local-only setup. In Home Assistant, all thermostats are disabled (turned off, not entity disabled), yet it still feels like the heating is running anyway.

The Zigbee integration exposes a lot of configuration options that I honestly don’t fully understand, like actuator type, heating type, sensor connectivity, etc. When I try changing some of them, things break. For example, if I change the heating type from “UnderfloorHeating” to “CentralHeating” (which is what I actually have, with a heat pump), I get an error saying:
“Failed to perform the action select/select_option. ‘uint8_t’ object is not iterable".

Living_Room
Living_Room2069×3555 329 KB

Recently there was an update to the Zigbee integration, and it feels like these issues started around that time, but I’m not 100% sure. The update added even more options, like cooling, which I don’t think my apartment even supports.

I’m struggling to find proper documentation for this specific Bosch thermostat with Zigbee in Home Assistant. I don’t really know which settings are correct, which ones matter, or how they’re supposed to be configured. On top of that, I don’t know how to reliably check whether my heating is actually running or not.

Right now it just feels way too warm for the current winter temperatures, especially considering that I’m supposedly not using my thermostats at all. Any pointers on how to debug this or understand what’s really going on would be appreciated.

2

Hi, welcome to the forum.
What kind of heating system do you have?

The insulation in new buildings is much better these days so this can be a reason for the temperature not dropping.
Another one is that your thermostat is doing what it’s supposed to do: heat when the temperature drops.

Do you have radiators, underfloor heating or anything else and what is used to create heat?
With radiators, it’s easy if you touch them to know what is happening.
If you have a boiler, you can see if it’s running (or not).

I wonder what (if) there is any effect from the -327° outside temperature…
One thing is to integrate thermostats but you also have to control them through an automation - created yourself or a blueprint like this one for instance: 🔥 Advanced Heating Control

3

There you go. Basements are always hotter then the upper flors in the winter because earth is keeping them warm. In the summer it will be the oposite.
You can buy a zigbee temperature sensor and see what it reads.
You can probably adjust your thermostat using better thermostat integration from hacs.
But your temp is probably true especially if you don’t feel any cold.

4

I recently purchased and installed two units RBSH-RTH0-BAT-ZB-EU which act as central heating control for my various Bosch RBSH-TRV1-ZB-EU that heat our appartment.
I also made the effort and compared the “local temperature” value of the RTH0 with external temperature sensors, that previously provided the ambient temperature in the rooms for the TRVs. I can confirm: the values match up to a variation of approx. 0.1 - 0.4°C so replacing the external temperature sensors with the RTH0 was the way to go for me

5

just in case, the Bosch Smarthome Controller runs local only, cloud is not required, neither with nor without HA, at least as you don’t run the security cameras or on purpose connect to the cloud to get access to data from external.
The controller runs a local web server and the Rest-API is published

6

Hi,

thank you for the kind introduction! To answer some of your questions:

What kind of heating system do you have? Do you have radiators, underfloor heating or anything else and what is used to create heat?

It is a central heating system, so no boilers or radiators. There is a water pump for the building that all 4 flats share. I have some controls for the heating in my bathroom, as seen in this picture:

Screenshot 2026-02-02 at 15.35.07
Screenshot 2026-02-02 at 15.35.071920×1436 223 KB

I wonder what (if) there is any effect from the -327° outside temperature…`

This value was set automatically when adding the integration. I think it can be used in automations to adjust heating based on the outside temperature. The Bosch thermostats support adding an external sensor. If I change the value to something reasonable it shows up on the thermostat, but nothing else happens from my point of view.

One thing is to integrate thermostats but you also have to control them through an automation - created yourself or a blueprint like this one for instance.

I have set up some basic automations, but the Zigbee Bosch integration supports features like target temperature that automatically turns on/off the heating depending on the set target. At least I think that is how it works?

7

I agree that the temperature is probably true, I just don’t think it is like that without any heating used. I remember my flat being colder before installing the smart thermostats, but I do not have the data to back this up.

8

That is good to know, I was actually not aware of this. I feel like the Bosch SHC integration is superior compared to the Zigbee based integration, but so far I did not invest the money in the SHC.

9

Never used the Zigbee integration, the controller came with the initial package.
But I don’t do much with the integration, other than reading states of thermostats or window contacts to display on screen. The heating schedule is configured on the controller, also the connection to the window contacts in each room to stop heating on open windows. No requirement to write any automations for that purpose in HA. The best smart heating for me is the one you can leave alone 24/7.

Back to your initial question: do you have perhaps configured an offset for the temperature? in your screenshot there is one entry where I can’t fully read the label, a slider with the label “Lokaler Temp…”
the thermostats allow to configure an offset to adjust the measurement taken directly at the thermostat

10

Hi
I don’t think your problem is TRV (thermostat radiator valve)

The diagram you’ve provided shows a control system for floor underheating, not radiators.

You have two independed heating systems.

If one turns off, that doesn’t guarantee a temperature reduction, as the second system could (possibly) compensate. Apparently, the underfloor heating alone is sufficient to maintain a temperature of 22°C in your apartment, as you indicated. If you want it cooler, you need to lower the underfloor heating or ventilate the room.

To check whether the radiators are turning off, simply touch them an hour after turning off heating on the TRV—they should be cool.

P/s Turning off the TRV doesn’t necessarily mean turning off the heating. When turned off, TRV enter their default state, which can be either open or closed. To ensure the radiator valve closes, simply set the TRV to a target temperature lower than the current temperature.

11

This looks like output on each loop has the thermostat and the input has the flow meter (or the other way around, I’m not sure which one is input and which one is output, but it doesn’t really matter for this). Which means you should be able to see if the loop is open or not by looking closely at the bottom part. The little floating thingy (probably red, hard to see on the photo) inside the transparent part shows the current flow in the loop. The lower it is, the higher the flow, but there’s printed exact numbers on there. If it’s close to 0, the loop is closed.

What you need to remember is that floor heating systems usually have a very big delay. That is, it takes hours to heat the floor and it takes hours for the floor to get colder once the loop was closed. Additionally, with a modern house in Europe (I assume) the insulation might be so good there’s barely any heating required to maintain the temperature, outside of the harshest winter. Additionally, you might be getting some heat from your neighbours, if they like it hotter than you do.

It’s quite possible that for example the thermostates only open during the night, and that’s enough to heat the floor so it keeps the apartment warm all day, and then you don’t really see them doing anything.