Pilot wire for electrical heaters

In another post, we have showned how to control a gas boiler with an arduino.

Today, we will show you how to pilot your electrical heaters via the pilot wire. This technology has been promoted by French heater builders such as Thermor or Atlantic and is described in NF C15-100. Total price : less than $40 !

What you will need is :

ArduinoUno_r2_front450pxAn arduino Uno : less than $30 (SparkFun)









And some electronics (less than $10):

  • Two 1N4007 diodes
  • Two opto-isolated triac MOC3041-M
  • Two resistors of 470 Ohm

Fortunately, you will need also to have heaters compatible with the pilot wire technology 😉

Pilot wire standard :

Pilot wire orderSignal
Comfort temperature no signal
Eco : Comfort temperature minus 3.5°C full alternance
Frost protection (maintain 7°C) half negative alternance
Heating Off half positive alternance

Time to make this working :

In order to generate the proper output and as we are playing with high voltage, we will use an opto-isolated triacs.

One triac will be used to drive positive altrernance and the other one to drive negative alternance. Here is the wiring scheme :

Fil_PiloteTwo digital output of the arduino will drive this little circuit.

10Heating Off
01Frost protection (7°C)
11Eco : Comfort minus 3.5°C

On arduino side :

What you will need to do is just to wire two outputs of your aduino, play with outputs and choose the setpoint you want to apply to your heater via the pilot wire.

Next step is to apply a specific heating program for each hour and day of the week. You can also even add an ethernet or a wifi shield to set up a Web server to be able to control your heating system from everywhere.

Enjoy 🙂

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