Fratelli TRV valve M28 x 1.5

I am interested in fitting out my home with Tado smart trvs, i currently have Fratelli TRVs which I believe are an m28 x 1.5mm thread.

In your documentation, you state that these valves are not support with adapters, but other M28 x 1.5mm valves are. I would like to know why they are incompatible, do you have a dimensioned cross section of the M28 adapter, that i could reference to see if there is anything I can do to make the adapter work?

I am not able to change the TRVs in my house as I have 14 radiator, and the cost of this would be prohibitive when then combined with the costs of tado.



  • As an update to this request and for any future searches, I have installed the TRVs on my radiators, slight modifications were required. you need to open up the hole the radiator pin moves through on the adaptor slightly, and I have had to cut down the plastic push pins supplied - but with this change they work perfect.

    this works for pettinaroli / fratelli TRV valves with M28 x 1.5 thread (my TRVs are connected to 10mm micro bore)

  • Hello, I'm coming a bit late but I've got the same issue than you.

    Would you be able to help me by sharing some pictures please

  • hopefully the drawing makes sense. you need to open up the base housing that screws on to the fratelli thread - the fratelli pin then partially sits in this. Then i cut down the Tado pin to 8.47mm, and used that (as shown in blue) to make up the gap to the tado plunger.

    Its important to not open up the hole too big, or the blue part will not be constrained very well.

    I have been using mine for 18months now, works perfect - much better than replacing my TRVs

  • Thank you for answering !

    Unfortunately I'm still lost, but I really appreciated that you took the time to answer me.

     I bought an M28 M30 adapter.

    But if I keep the piston of the adapter, I can't screw the adapter and if I remove the original one is too short.

  • After a brain break, I was able to do it thank you !