Heating not turning off when temperature is reached on thermostat

[Elliot96]

I have a Danfoss thermostat which is normally set to 19 degrees. When the temperature of the room has been reached the hearing used to turn off automatically. Recently it has just been getting hotter and hotter. I have tried to turn the heating off via the thermostat but the radiators just keep pumping out. The only way to turn it off is by turning off the boiler which obviously isn't ideal.

How can I solve this?

 

[alan333]

I'm not a heating expert but it sounds likeyour thermostat is faulty.

 

[D_Hailsham]

Do you have any motorized valves (as in the pic)?

If so, how many?

[GALLERY=media, 11762]2 port Valve by D_Hailsham posted 25 May 2009 at 8:59 PM[/GALLERY]