The Conrad FHZ1000 (AKA ELV and eQ-3) uses the FS20 automation system and can control a large number or TRVs. I believe this is the same interface used by OpenTRV. A CUL dongle running culfw will also control a number of TRVs. There’s also a webinos project that also uses this protocol.
Resource for Domestic Heating Smart Contollers