Arduino and Raspberry Pi Project.

16 KW Electric Water Heater

2013-03-31 - Johan Sandbeg V 0.3

Electric Water Heater - Autoterm G-3 built in 1990

This project is done to replace the electronics on an outdated electric water heater that was heating our home.
The outdated system was installed in 1990 and the controller electrinics was bild with an analog curcuit with a few IC:s.
Maximum effect on the 3 x three phase AC heating elements is 16 KW and this is enough to heat our 200 m2 home.
The hot water is distrubuted to the floor heating system with separate sections eoth for each room.

Sensors are placed on the following locations.

Outdated control panel.                                         Electronic curcuitboard.                     AC 380V Current Sensors to limit maximum current < 25A.   

3 x 3 phase heating elements, 2,25 KW + 4,5 KW and 9 KW

New Control System built with Arduino and Raspberry Pi

The new control system is built using a Arduino Nano to control the heater and a Raspberry Pi for the web interface.
There are three main parts in the new system.

Controller I/O and Sensors

Temperatur sensors:             I tested a number of different sensors and the Maxim (Dallas) DS18B20 was finally selected.


Real Time Clock - RTC      A real time clock RTC with battery was needed and I selected Maxim DS1307.

Connecting the Arduino nano to Raspberry Pi using serial ports


Arduino is running on 5V and RaspberryPI on 3.3V so a logic level converter is needed to connect the serial ports on each device.
For this am using the Sparkfun Logic level converter BOB-08745

Building the prototype Controller

Prototype development board built on plexiglas.

Homebuilt Power Supply +5V               Arduino board attached ontop                4 Channel Relayboard
                                                            of Raspberry Pi       


Parallax 4x20 LCD Module               New replacemet modul board.           New Aluminium front panel.