Have installed 927 stat it looks great but it takes for ever for house to heat up. New powerful boiler grant vortex oil 26-36kw. stat is set to oil boiler as recommended by Honeywell and optimisation is enabled but it is not bringing the boiler on enough to heat house. Stat is in hall where the rad has a manual valve fully open all other rooms have TRVs. WE have 11 radiators bot only 4-5 are on at any one time. Heating comes on at 4.30 afternoon target temperature is 19 deg. It is between 8-9 pm before it reaches this from a starting temperature of 16 deg. Would be grateful for any advice. Setting on boiler is 70 deg and I was told by Grant Technical people not to put the boiler to full. Although I read in various reports that boiler should be on full when controlled by a room stat. This is a new boiler £1200 condensing I can only assume the makers know what they are talking about and I am worried that I may have problems with warranty validation. . In the Honeywell literature no mention is made that I can see about what temperature boiler should be set at. But surely the CM927 should be bringing on boiler more often to reach target temperature. In literature it mentions that the boiler cycles 3 times per hour - each cycle 4 mins. I am baffled.