Control of electric central heating by diode? [SOLVED]

Hi all, I'm new to arduino, i unboxed my first Arduino uno yesterday, and i'm interested in controlling my Electric central heating in my house.

I Live in France, but am British, In France they commonly use electric heating, centrally controlled by a programmed driver unit. the contol to the heating is by means of a "fil pilote" a control wire, which signals the choice of different modes to the wall mounted heaters by clipping the ac 240v signal thus:

Confort=comfort(the highest setting)
Eco =same as comfort but a few degrees lower on the thermostat
Hors gel =Freeze protection
Arret =off

currently i can choose to have either all rooms on high/low/freezing protected/or off. what i would like to be able to do is to either split the house into two or more zones, and keep the main living area warm during the day, and then heat the bedrooms just prior to bedtime.

My question is really some advice to get me going in the right direction. I understand that i can use a diode to clip the signal of the ac to the correct profile to switch modes. but i am not sure how to control this by arduino, should i look for some kind of switch to direct the control signal thru diodes in different configurations? or is there a more simple method?

Any advice would be welcome. I have a little background in electronic. but feel free to treat me as a novice.



I think you could use SSR ( solid state relays ) connected to PWM outputs of arduino . This way you can control electric heaters " from 0 to full" . Add couple of DS18B20's temperature sensors to sense room's temperatures, LCD to present current settings and states , coulpe buttons to set desired temparature an you have automatic heating control :slight_smile: With arduino this is very simple and you will find all info just by serching " arduino thermostat" , "arduino thermometer" , " arduino heater controll" , "arduino PWM " etc.

Thank you for your input. Can you explain more how i could use ssr's to acheive the control. i would be happy to be able to switch between the state's of freeze prevention and full, after that i agree more control could be added, and as you say there are plenty of examples to show this next step, it's just the first step of interacting with the control wire that i am sticking on.

Look at " PWM" firs : Pulse-width modulation - Wikipedia . With PWM you can control your heater "fluently " not just with two states. Imagine this as a volume knob on your radio - it lets you set desired volume very precisely. Arduino is capable of producing PWM signal and it's quite asy to do so : . SSR is like a switch but it's electronic :slight_smile: When you google " arduino ssr" you'll find good explanations on how to connect them together. First, you have to know how many watts does one heater have and knowing that, you have to choose right SSR .
There's many ways of doing what you want - some are very simple, some are a little bit more complex . Just remember - youl'll be dealling with mains voltage ( 230V ) whitch is dangerous to you, your fammily and your property . You really have to know what you're doing. If you don't - put your arduino , ssr or/and any ther hardware togheder and let your electrician connect it to heaters and mains :slight_smile:

Ahh, ok , i think i understand, so instead of simply modifying an existing 240v ac supply to give the correct signal, i could just use the arduino to generate a new signal to send to the control wire. I will do some research on pwm to see how i can do this.

Thanks for the suggestion.

Actually.. after re-reading your comment about the radio volume control, i think there may have been a misunderstanding. The 4 modes mentioned are selectable by sending this signal of 230v, the clipping of the signal is not to send a different voltage to the element, but to command the heater to select a different mode... It is a strange system to me, and it seems to be unique to france from what i have read....

I believe sending a voltage other than 230v mains to the system would not mean less heat.

The individual heaters have a thermostatic controller on them with manual selection of the above modes, or an auto mode where it reads the pilot wire signal to select the mode.

So can you reconfirm if this is possible to do with pwm, or is using some kind of system of diodes the only solution?

Thanks again..

It is possible to use PWM. To do so, you'll have to switch heaters to "manual" and "brake" their power supply by a SSR controled by arduino. SSR will clip mains power to provide what you are looking for. Volume knob was just an egzample ( a bad one :wink: ) to show that PWM gives "infinite" ( well... allmost :wink: ) amount of "states" to control a device ( heater ) . With arduino you can build your control system the way you want it - Measuring temperatures is every room, setting different temperatures in different rooms ( offcourse with closed doors and with some "tolerance" ) , setting different temperatures for different hours, days etc, and even controling everything from your laptop, mobile phone or tablet ( with litle extra hardware and some extra reading :wink: ) It may look difficult at first but walk through every problem step by step : learn what PWM is, read how to choose and use SSR , how to connect it to arduino then read about writing simple codes for arduino. Everything is here :slight_smile:

PS - I wish I could explain everything better but English isn't my native language :wink:

Thanks for the response again. I will continue to research. I am always greatful for any responses. Are there any other people out there with idea’s the same or other.

waski, no need to apologise for your English skills, i know what it’s like to try to communicate in a second language.



Je peux te répondre en français :slight_smile:

Tu peux utiliser des relais "classiques" :
Le plus simple : marche/arret via le fil pilote : 1 relai qui connecte la phase au fil pilote via une diode (alternance vers le bas), ou qui deconnecte la phase du fil pilote (confort)

Plus compliqué : 3 relais qui sont connectés au fils pilote comme sur le schéma :

si aucun relai activé : mode confort (aucun signal sur le fil pilote)
si relai 1 activé : mode eco (phase complète sur le fil pilote)
si relai 2 activé : mode arrête (phase positive)
si relai 3 activé : mode Hors gel (phase négative)

A mon avis ça doit marcher !

Après tu peux supprimer un mode qui ne te serai pas utile pour économiser un relai et des sorties sur ton arduino

Thanks, Thats what i was trying to get to. Merci pour votre assistance :smiley: