Honeywell offers a wide range of radiator thermostats. For further individual information, click on the product links to the left. Thermostats are used to control individual rooms or zones in a wet heating system. They are also effective in compensating for uncontrolled heat inputs such as solar gain and open fires. Radiator Thermostats should not normally be fitted in rooms controlled by a room thermostat. All our radiator thermostats are fully CEN compliant.