Noisy smart thermostat heads

[Pyrotech]

I have installed a wiser kit 1 to our 3 storey town house due to the temperature difference between floors. The system works well in conjunction with wet underfloor heating on the ground floor. However, the noise the smart thermostat heads make is okay in most rooms, but in the bedrooms when the heads open or adjust, the noise is loud enough to wake us. We do have large radiators which seem to resonate making the noise more pronounced. Does anyone have a fix that would make them significantly quieter?

My alternate solution would be to reinstate the traditional radiator thermostats on the top floor and install a motorised zone valve to control the flow to that level, activated by a wiser micro power module. Does anyone have a better solution, or a way to silence the smart radiator thermostat heads?