So you got a Ferroli Optimax bolier with the built-in programmer/clock and you are replacing it with this ROMEO W RF wireless OpenTherm thermostat:
You've connected the RF bridge, powered up the room unit and got RF comms going, but you get a fat "F" or "E" fault codes displayed on the room unit and the built-in programmer/clock displays "NoCN" or "NoCM":
The Ferroli manual doesn't tell you to disconnect the programmer/clock after installing the RF bridge. To fix the problem, disconnect the programmer/clock by pulling out the wiring loom going to the back of the clock out and leaving it disconnected.
Note: if you also want to control your boiler from your phone/Internet, read the following
Remote boiler control with Ferroli ROMEO W/RF OpenTherm thermostat and Marmitek UM7206 X10 module
http://blog.belodedenko.me/2015/01/x10-remote-boiler-control.html
