HR91 - Room temperatue exceeds set temperature

[FlossyThePig]

Now the colder weather has arrived a recurring problem has started again which I have never really solved.

My system is quite large with 18 cast iron radiators spread over 10 zones. All radiators have HR91s fitted.
There are only two of us in the house now, and we spend the evenings in a small sitting room with one radiator. The maximum target temperature is set to 18.0° but the room can get very hot with the HR91 reporting a temperature of 28.5°.
The settings for the room are:
06:00 - 14.0° | 07:20 - 15.0° | 18:00 - 15.5° | 19:00 - 17.0° | 20:00 - 18.0° | 23:30 - 13.0°

Does the problem lie with having cast iron radiators that retain the heat compared to steel panel type radiators.
Has anybody got suggestions for a solution.

[Somebody]

Check the batteries.

[Richard]

Sounds like you have the evohome controller set as the zone senor for the zone. Contact support to assist - 0300 130 1299.