Expand your knowledge about Electric Thermostats

  • about electric room controls

    Do Danfoss programmers automatically swap between winter and British summer time?

    No. As a general rule pressing the plus (+) or minus (-) button will toggle between winter and British summer time.

    Please refer to the user instructions for your specific model.

    I can set my 103E5 (GP Timeswitch) and go through all the functions but it still does not work. What does this mean?

    If the programmer is failing to work there is no mains power getting to the unit. Check the mains power supply.

    I have a 103E7 / 102E7 but the instructions on your web site do not correspond?

    There are older versions of the 103E7 and 102E7 (purchased before 1994) which pre-date the instructions on the website.

    Is it possible for wireless thermostats to interfere with each other?

    No. These devices use unique identity coded radio signals that ensure secure communications.

    Where can I get a replacement slider switch for the 922?

    Replacement slider switches for the 922 are not available. A direct plug-in replacement for the 922 and 972 is the FP975.

    The battery symbol on my FP715, CP715, TS715, 103E7, FP975 is flashing.

    For these models of programmers, the battery is used as a back-up power reserve to hold the programmed settings during a power-cut. If the battery symbol is flashing then this means that the mains power is not getting to the unit. You will need to check the mains power supply to the unit. The battery is non-replaceable as it is soldered into the unit.

    Where can I get a replacement battery for a 702?

    The battery in the 702 programmer is only used to hold the programmed settings during a power-cut. If there is a power-cut you will have to re-programme the unit. The Varta 600DK battery is no longer available. Varta stopped manufacturing it 10 years ago, and we cannot source a replacement manufacturer.

    The following Danfoss controls are standard battery powered models. They all take 2 x high quality alkaline AA size batteries - TP5000, TP7000, HC6000, WP75-RF and RET-B.

    I am looking for a direct replacement control that can be simply plugged onto my existing wallplate.

    102 - direct replacement is 102E5 or 102E7
    103 - direct replacement is 103E5 or 103E7
    SET3 - direct replacement is SET3E
    SET5 - direct replacement is FP975
    3022 - direct replacement is 3022 FRU
    3060 - direct replacement is 3060 FRU
    4033 - direct replacement is 4033 FRU
    911 - direct replacement is TS715Si
    971 - direct replacement is TS715Si
    922 - direct replacement is FP975
    972 - direct replacement is FP975
    SET1 - direct replacement is SET1E
    SET2 - direct replacement is SET2E
    SET3 - direct replacement is SET3E
    SET4 - direct replacement is SET3E

  • 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.

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