Hi Volker, maybe you can put this in your knowledge base if you think it is useful:

Loose Fit Tip - when trying to use Eve Thermo on old Drayton TRV3 valves, using a ‘Tensor HS-TRVD-AD Adaptor for Drayton TRV3 Thermostat Radiator Valves’ adaptor made by Tensor and sold by Heatingsave in the UK. The issue is that even when tightened to the adaptor, the Eve Thermo remains loose when the valve is fully open (24’C-30’C), even after multiple calibration attempts. A 0.5mm (maximum) thick metal shim/washer/spacer with an Outside Diameter (OD) of 26mm and an Inside Diameter (ID) >6mm fixes this. The spacer is placed between the new Eve Thermo and the adaptor, so the Eve Thermo tightens perfectly onto the adaptor and is no longer a loose fit.

F.Y.I. The adaptors can be purchased from this website and are £10.47 each.
Postage is high, but this is how the companies flat rate shipping is done unfortunately.

These adapters save a lot of work and money replacing old valves though, so I think it’ll be worth it. I am currently testing the adapter with one Eve Thermo and will install another 3 soon, so let me know if you are interested in the outcome.
Oct 26, 2022