Installing a heating programmer: the complete guide

Programming your heating means the certainty of coming home to a warm house without heating all day long. A heating programmer automatically manages the heating periods according to your presence, lowering the temperature at night and during absences. According to the French ecological transition agency (ADEME), programming your heating well can represent savings of around 5 to 15% on the bill, without losing comfort. The installation does, however, require working on the boiler's electrical circuit: it must therefore be carried out methodically and, if necessary, by a professional.

Wired, radio or connected programmer?

• The wired programmer: installed in place of the old thermostat, it is connected directly to the boiler by wires (models from 30 to 60 €)
• The radio programmer: the sensor and the boiler communicate wirelessly, practical if the consumer unit is far away (50 to 120 €)
• The connected thermostat: controllable from a smartphone, with presence detection and automatic optimisation (80 to 250 €)
• Some programmers combine heating and domestic hot water: check the control zones you need

Choosing a model compatible with your boiler

Before buying, check the type of your installation: gas boiler, oil boiler, heat pump or electric heating are not all controlled the same way. Most modern programmers replace an existing wired wall thermostat (two or three wires), but some old boilers require a specific model or an intermediate relay. Read the manufacturer's instructions carefully: if your boiler has no terminal block dedicated to the thermostat, or if the wiring does not match the supplied diagram, call in a heating engineer or an electrician. A wrong connection can prevent the boiler from starting or, worse, damage its electronic board.

Installing a programmer: the steps

1. Switch off the power at the circuit breaker for the boiler circuit and check the absence of voltage with a tester
2. Remove the old wall thermostat by taking off the faceplate then the mechanism, and photograph the existing wiring
3. Identify the wires: generally locate the thermostat terminals (often marked T1/T2 or COM/NO on the boiler)
4. Remove the wires from the old box, strip them to 6 to 8 mm if necessary, and connect them to the new programmer following the manufacturer's diagram
5. Fix the programmer's base to the wall (about 1.50 m from the floor, in the main room, away from heat sources)
6. Refit the programmer, restore the power and set the time, date and temperature schedules
7. Test each mode (comfort, eco, frost protection) checking that the boiler reacts correctly

Programming intelligently to save energy

• Heat to 19 °C during the day in the living areas and to 17 °C in the bedrooms
• Lowering the heating by 1 °C in eco period generally corresponds to about 7% savings on heating consumption
• Lower the temperature at night (16 to 17 °C) and during absences of more than a few hours
• Trigger the heating restart 30 minutes to 1 hour before your return depending on your home's thermal inertia
• During long absences, use the "frost protection" mode rather than switching the heating off completely

The mistakes to avoid

• Swapping the wires when connecting: boiler that does not react or risk of short circuit
• Forgetting to switch off the power before working on the wires
• Installing the sensor in a room that is not representative (hallway, bathroom) or near a radiator
• Choosing a programmer incompatible with the boiler type, without checking the instructions
• Believing that programming is enough: an annual boiler service remains essential to its good efficiency

Installing a heating programmer is within reach of a methodical DIYer when the wiring matches the existing diagram. In doubt, on a recent boiler with electronic regulation, do not hesitate to entrust the installation to a professional: the cost is quickly recouped by the savings made. Once installed, take a few days to fine-tune your schedules: the aim is to heat at the right time, at the right temperature, without ever wasting.