ᐅ Shower: Is it possible to convert this single-lever mixer to a thermostat valve?

In the relatively new house (4 years old) that we are renting, there is unfortunately only a single-lever mixer installed in the shower. It has actually annoyed me from the start, especially since I installed a rain showerhead, but even more so because you often adjust the water flow and the temperature changes at the same time (which is really tricky with kids). Therefore, a thermostat would be much more practical.

Now, I’ve only seen these thermostats in one version, where the water is supplied from two sides. However, we have a single-lever mixer here without any visible water supply lines. So my question is: Is it possible to convert this to a thermostat, and if so, is that feasible in a rental property, or would it require irreversible modifications?

Thank you very much in advance for any ideas on this topic 🙂

Are there any details I need to add so that someone can comment on this, or is it simply not possible?

This is a concealed valve; the manufacturer could be identified by removing the lever, but fluctuations in water pressure while showering are not normal. Most likely, a low-quality product was installed.

Replacing it is very difficult since it is concealed.

Please provide some information about the manufacturer.

If the amount of water remains the same, the temperature stays constant and there are no fluctuations. Only if, for example, the amount is reduced, does the temperature increase, but it remains constant as well.

Okay, if a replacement is basically not possible anyway because of the concealed installation issue, then I think I’ll save myself the effort of dismantling :/

Behind it is a built-in unit. Replacing it with a thermostat is usually not possible without additional modifications.

Jumping in here... @Mycraft, more out of curiosity since I have thought about this before...

Someone once told me (although not a professional) that in some cases a later retrofit is possible. For example, I have a Hansabluebox with a shut-off valve. But I dismissed the idea because it didn’t seem worth paying a few hundred euros to replace an almost new faucet.

- Is this generally possible with the Hansabluebox?
- How does it work then? For a faucet, I need both water flow control (with a diverter for overhead/hand shower) and temperature adjustment. Usually, these are separate controls.