The control valve is located near the bottom of most radiators. On a steam radiator, it is the valve on top of the pipe leading into the radiator. It will look like a small, rounded cap. Turn it as far as possible to activate the radiator.  This smaller valve controls the flow of water in traditional steam radiators. Turning the dial clockwise shuts it off. There is no in-between setting. Modern electrical radiators often have control panels instead of dials. Press the “on” button to start the radiator, then use the panel to adjust the heat setting. Some caps aren’t connected to the valve itself. Test this by pulling the cap up. If it pops off easily, you will need to turn the valve manually. Grip the metal valve with the pliers, then turn it counterclockwise to activate the radiator. Replace the cap after turning the radiator on. Some lockshield caps are held in place with a screw. If you see a screw on the top of the cap, turn the screw counterclockwise to loosen it and remove the cap. Look on the opposite side of the radiator for a second valve. The thermostatic valve usually has a taller cap with numbers ranging from 0 to 5. It’s like a dial on any other type of heater. Turn the valve counterclockwise to increase the heat and clockwise to reduce it.  The thermostatic valve controls the amount of heat escaping the radiator. Setting it at 0 prevents heat from escaping, but it doesn’t turn off the water or electrical flow. Old radiators may not have a thermostatic valve. You will see a vent valve, sometimes with an adjustable component. These radiators aren’t designed for heat control, so consider having a professional install a thermostatic valve. The frost setting is represented by an asterisk or snowflake symbol on the thermostatic control. It is usually between 0 and 1 on the valve. If you are away from home during a period of freezing weather, turn on the frost setting to protect the radiator from damage. The frost setting keeps the radiator at a low heat level so the liquids inside of it can’t freeze. The radiator functions like any other water pipe in your home. Ignoring it can lead to a burst pipe and a big repair bill. No matter what type of radiator you have, use the control valve to turn it off. It is the valve that controls the water flow to standard radiators. For electric radiators, press the off button on the control panel to shut off the radiator’s power supply.Turning a thermostatic valve will not shut off the radiator all the way. Use the thermostatic valve to control the temperature, but always go to the control valve to stop the radiator from emitting heat.

Summary:
Turn the radiator dial counterclockwise to turn it on. Use pliers to turn on the radiator if it has a lockshield cap. Spin the thermostatic valve to control the radiator’s temperature. Use the frost setting to prevent the radiator from freezing. Turn off the radiator by twisting the control valve clockwise.