AFAIK (at least here in Italy) the "standard" is M 30 x 1.5 mm, so the actual thermostatic cartridges are generally that size. The document you posted (which i

AFAIK (at least here in Italy) the "standard" is M 30 x 1.5 mm, so the actual thermostatic cartridges are generally that size. The document you posted (which is very nice BTW) indexes all the existing valves so it makes IMHO the (actually problematic) situation seem worse than it is (because the actual diffusion of this or that type of valve isn't taken into consideration). Check this: https://support.tado.com/hc/it/articles/212050583-Con-quali-valvole-sono-compatibili-le-Teste-Termostatiche-Intelligenti-Ho-bisogno-di-un-adattatore-per-montarle-correttamente- https://support.tado.com/hc/it/articles/212050583-Con-quali-... basically all M30x1.5 are not listed as they are directly compatible. Then, 11 most common types are listed, and for the first 6 ones (the most common among the non-M30x1.5) the adapter is included. From personal experience (anecdata, so take it with a grain of salt) the "standard" M30x1.5 + Danfoss + Giacomini + Caleffi cover really nearly 100% of what people can find in their home. These other guys here say that a basic set of adapters cover 90%: https://www.youtube.com/watch?v=u5KOMFlDbhE https://www.youtube.com/watch?v=u5KOMFlDbhE https://s3-eu-west-1.amazonaws.com/common-data-files/static/2017-05+Leaflet+for+Valves+Adaptators-WEB.pdf https://s3-eu-west-1.amazonaws.com/common-data-files/static/...