Heater controller hardware

Starting from hardware side of things, all components were tested separately on breadboard. Putting all this together in a manageable package is just a bit of work.

The compnents used here are:

1x Arduino Duemilanove board

1x Nuelectronics Ethernet Shield V1.0 for Arduino

1x some kind of case. I used a breaker box case.

1x external power adaptor. 12v

1x JQC-3FC 12V relay

3x lm35 temperature sensors

3x DS18b20 temperature senosrs

5x leds. One green, two blue and two red ones.

1x CNY17-2 optron

1x 1N4007 diode

1x PN2222A transistor

1x 4k7 1/4w resistor

1x 150R 1/4w resistor

3x 10R 1/4w resistors

1x 2k2 1/4w resistor

5x 1k 1/4w resistors

6x something to shield sensors from elements.

some wires, and some screw terminals for connecting wires otside the case.


Why so many components?

Leds and 1K resistors go hand in hand and are not essential, but then again they give a good status overview. Also a lot less sensors can be used. About half of them are actually not used by the software.

A bulk of those components are consumed by relay schematics.

Also a place for second relay is prepared in that case, but it is not installed. I might use it for controlling an electric boiler.

Inside of that box could be made a lot more cleaner, by not using airmounting for example, but it is the way its is right now.

Outside of the box looks quite ok. Three of the five leds are illuminated. Some kind of labels for leds should be written. From left to right they are

Green – power / idle / working

Blue – first one – day mode active

Blue – second one – night mode active

Red – first one – heater relay active

Red – second one – boiler relay active

Otside of the box


Arduino USB, power and ethernet look like this:

USB cable is connected for testing purposes only 🙂

Usb, power, ethernet


Sensors and relay connectors look like this:

It would be a lot cleaner when only one wire devices were used. As can be seen here, one wire (BUS) connectors are connected in star formation. Parasite power of course.

Sensors and relay


Inside is not so neat. I should of mounted components on some custom boards, should of used more different colored wires etc but here it is.




Look from a different angle, so lower connectors can also be seen:

inside, angled


Total cost of hardware about 130 €


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