I'm thinking about swapping out my old dial Switchmaster room stat for a digital one. I have an open vented system with a Baxi Solo 24 HE boiler controlled by a Drayton 241 programmer which controls CH & HW separately. I was thinking about going for a Honeywell DT90E which would just have the same function as I have now but have also noticed the CM907 programmable stat which appeals to me as I can set different temperatures at different times. My question is as I already have the CH set on the timer, will there be any issue with running a programmable stat as well? I would like the stat to change temp at different times but do not want to use the timer function if that makes sense? I.E the programmer CH is set to turn on between 6pm and 11 pm but would like the stat to set the heating at 18 degrees between 6 & 9 and 21 degrees between 9 & 11. Could I leave the Drayton Programmer CH function 'on' all the time with the CM907 controlling when the boiler turns on, or would I need to set the programmer and the programmable stat BOTH to the same time to turn the heating on?