Hi! I have an Ideal icos HE standard boiler with cold water tank in roof, hot water lagged tank in airing cupboard it is five years old. All worked really well last year, pump was replaced three years ago. The boiler is firing and not showing any faults when the hot water is on. The radiators all have thermostatic controls except for the one where the room thermostat is. I turned the radiators on but they only heat up when the hot water is being heated going cold when the tank if hot. I replaced the batteries in the room thermostat as they had died and set to 21 degrees yet there doesnt appear to be any communication between the room thermostat and the boiler eg the boiler doesnt fire to meet the requirements of the thermostat which is currently 18 degrees. I have tried putting it on Heating Advance but nothing happens but if I put the Hot Water Advance on the boiler fires and the radiators heat up - help!!