Do You use a floor heating system from LK Systems ?
We had a problem that in some rooms, despite that the thermostat worked, the temperature was to high.
To check if it was the valve, or something else, I just took away the actuator and forced the valve to be closed. Cable ties did the work.
The valve was OK so what was the problem ?
After some Googling i found that the actuator LK A4104 is of type NO, that is Normally Open. This means that if the controller or he actuator fails the valve will be left in the open state, the room will be warm.
According to the data sheet the start up current is 250 mA and the operating current is 80mA. As the actuator is supplied with 24V this gives a resistance of something between 96 and 300 Ohm. So measuring all the actuators I found that 6 out of 14 where defect ? (Installed in 2009) The OK actuators had a resistance of about 120 Ohm and the defect ones had a resistance greater than 2KOhm
The mentioned actuator is replaced by LK Actuator NO with RSK no 241 75 91 but when unpacking the new once they where still labeled with LK A4104 ?
After changing the defect actuators it all works fine again. So when the thermostats don't call for any heat the valves are really closed.
The gear that is used to regulate our floor heating is
LK Cq 8N Receiver unit, 8 canal
LK Cq Wireless room control
they are all expired so if You have the same equipment, take care!
If You have problems with the room controls, thermostats, it could be oxide on the battery connections. Please follow these instructions.