The Eberle room thermostat with product ID "111 1104 51 100" (RTR-E 6202) can theoretically be installed in place of a Siemens rec24dc, but there are some important considerations:

- Compatibility: ensure that the electrical and mechanical connections of the Eberle thermostat are compatible with those of the Siemens rec24dc. This includes checking the terminals, voltage requirements and mounting method.

- Functions: The Eberle RTR-E 6202 is a simple room thermostat, while the Siemens rec24dc may offer additional functions such as programmability or remote control. Make sure that the functions of the Eberle thermostat meet your needs.

- Installation: It is advisable to compare the installation instructions of both devices and, if necessary, consult a professional to ensure that the replacement is carried out correctly.

If you only require a simple controller, the Eberle RTR-E 6202 should fulfil your requirements, provided that compatibility and installation are guaranteed.