Fixing a stuck thermostat (TA RVT) on your central heating radiator

Is your radiator cold or gives very little heat? Or is it burning hot, no matter how you turn the knob on the thermostat? Then the problem is probably caused by the thermostat being stuck.

Use this instruction on your own risk. If you feel unsecure about it, call a professional. This instruction applies to central heating systems using water and a thermostat called TA RVT. If your thermostat is of another type it is possible that the procedure is similar but not necessarily. Go on with caution.

1. The thermostat needs to be removed. It is done by unscrewing the metal ring. There should be no danger for leaking water by doing this. If you have a different type of thermostat than the one in the picture, unscrew it a little bit at a time checking that no water is starting to pour. If it does, screw it right back again. You will probably need a tool for this.
   
2. Use a tool to loosen the metal ring. Then unscrew it by hand.
   
3. Gently pull the thermostat off.
   
4. The pin is probably stuck in closed or open position causing the radiator to be cold or over heating. Put a drop of oil at the base of the pin.
   
5. With a tool, gently exercise the pin by pushing on it until it starts to move. It should move about 3 mm from it’s innermost to the outermost position.
   
6. Remount the thermostat.

While you’re at it, it can be a good idea to empty the radiator of any air pockets. Especially if you live in the top levels in the building. Air pockets in radiators reduces their effectivness. You need a special little key for the purpose. You can probably find it at your local hardware/tools store.

1. Find the air outlet of the radiator. It normally looks like the one in the picture.
   
2. Use the key to gently open the valve. Let all air out until the water starts to pour. Be prepared to catch the water in a cup. When there is only water without any air coming out of the valve, close it again.