vaillant 438 heat onlt boiler + VR 65 Control Unit + 140 Time Unit

[Richard at Home]

[FONT=DDG_ProximaNova][/FONT]I have a vaillant 438 heat only boiler running a 140 Time clock and a VR 65 control unit

I am looking to update the time clock to a VRT392 Programmable Room Control

I have read that this time clock needs the new VR66 unit

What is the difference between the VR65 and VR66

Will my VR65 work with a new VRT392 wired time clock or would i need to replace for a VR66

If you feel there is a better time clock in the price range any advise will be gratefully received

Thanks

Richard