Electronic Thermostats

  • Glossary of features

    Boiler anti-cycling device

    A device to introduce a time delay between boiler firings. Any energy saving is due to a reduction in performance of the heating system. The device does not provide boiler interlock.

    Boiler interlock

    An arrangement of the system controls, which ensures that the boiler does not fire when there is no demand for heat, achieved by fitting a room thermostat, correct wiring interconnections between the room thermostat, cylinder thermostat, and motorised valve(s) or a suitable boiler energy manager.


    A feature within a device, which fires the boiler at regular intervals to maintain a set temperature. This avoids the room temperature dropping off between programmed events before the boiler fires up to achieve the set temperature again and is more fuel-efficient, ensuring a constant ambient temperature.

    Delayed start

    This feature delays the start-up of the heating, depending on how warm the room temperature already is at the time when the central heating is scheduled to come on. Therefore during milder weather, when the ambient room temperature is normally higher, the heating start time can be delayed to avoid wasting fuel by switching the heating on earlier than necessary. In most cases, this feature reduces the number of hours per day that the system runs, with no resulting loss of comfort, thus cutting fuel bills for the home owner and helping the environment by being more energy efficient.

    Intelligent electronic anticipator

    A feature to improve fuel economy and efficiency. Measures the rate of temperature rise, and then by anticipating when the set temperature will be achieved, switches off the boiler, using only the residual heat in the system to reach the final temperature.

    Load compensator

    A device or feature within a device, which adjusts the temperature of the water circulating through the heating system according to the temperature measured inside the building.

    Locking & limiting

    A feature in a radiator thermostat for locking the temperature sensor to disable alteration of the set temperature.

    Optimum start

    A feature within a device to adjust the starting time for space heating according to the temperature measured inside or outside the building, aiming to heat the building to the required temperature by the programmed time. This feature may delay or advance the boiler start time to ensure rooms are up to temperature by the programmed time. This feature takes into account the varying climatic conditions of the UK, whereby there may be frost one morning and a milder temperature the next. As a guide to possible savings, let us assume an optimum start control can save an average of 30 minutes a day Heating ‘On' time (morning and midday) during a 220 day heating season. This calculates to 110 hours (4½ days) unnecessary heating being saved annually. The bigger the home and heating bill, the more important this becomes.

    Positive off

    A feature within a radiator thermostat that allows the valve to be completely shut off for easy removal of the radiator. This avoids the need for draining down of the whole system. You need to remove radiators in order to redecorate.


    Valves with this feature allow the commissioning engineer to precisely set the calculated flow of water to individual radiators without the need for costly and inaccurate temperature measurements. They also reduce the function of the lockshield valve to one of isolation rather than regulation.

    Pump over-run

    A timing device (usually built into the boiler) to run the heating system pump for a short period after the boiler stops firing to discharge very hot water from the boiler heat exchanger.

    Radio frequency controls (RF)

    These are controls designed to send and receive signals to switch the boiler and/or pump by radio signals through the air so avoiding the need for normal electrical wiring.


    A device that requires no input from another control to instigate its own action. EG: RAVI thermostatic cylinder thermostat, a non-electric solution thermostatic sensor controlling hot water temperature in a cylinder.

    Snap lock

    A connection method for attaching a sensor to a radiator valve requiring no extra tools.

    Weather compensator

    A device or feature within a device, which adjusts the temperature of the water circulating through the heating system according to the temperature measured outside the building. This feature reduces the water flow temperature as the weather becomes milder to maintain room temperature at the required level.

Be social Take part

Want to socialize with us?

Get to know us and take part in the conversation