Thermostatic radiator valves have sensors, containing a wax or liquid, that expands as the room temperature goes up and contracts as the temperature goes down. When the sensor contracts, the valve opens automatically to allow more hot water to flow to the radiator, and when it expands, the hot water flow is restricted. 

Hence, a thermostatic radiator valve (TRV) senses the room temperature and automatically adjusts hot water flow to the radiator to maintain a constant temperature in the room.

tado° Smart Radiator Thermostats are not compatible with RTL valves, which are used in underfloor heating systems.

Smart Radiator Thermostats measure the ambient air temperature, and return temperature limiter (RTL) valves measure the water temperature within the connected pipe.

A manual valve (non-thermostatic) is a simple on/off valve that works like a tap. It regulates hot water flow to the radiator and changes the room’s temperature only when it is manually turned on or off.

While most thermostatic radiator valves have numbers, screens or other control buttons, manual valves usually have no numbers or buttons. There may be plus and minus (or on and off) signs on a manual valve indicating the direction you need to turn it to.

Once the valve head is unscrewed, if the valve has a pin that can be pushed in and out, you can be sure that your valve is thermostatic.

The tado° Smart Radiator Thermostat works only with thermostatic radiator valves and it replaces your existing thermostatic valve head.

If your radiator has a manual valve, consider getting it replaced with a thermostatic radiator valve which will then let you install the tado° Smart Radiator Thermostat.

Tip: By replacing your manual valve with an M30 X 1.5 mm thermostatic radiator valve, you will be able to install the Smart Radiator Thermostat directly, without an adapter. 

If you are not sure whether your radiator valves are thermostatic or manual, please check this guide for more information. 

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