I have decided to move from a honeywell cm927 thermostat to Evohome to enable me to gain more control over individual radiators and rooms. I have an Ecotec plus 831 combi boiler which was installed 4 years ago along with new radiators and pipe work. Can anyone advise what kit I will need to do this and do I need to use a new BDR91? If not can I buy the Evohome thermostsat without the BDR? Many many thanks in advance..