We live in an apartment fitted with these electronic heaters. They have two problems (besides the generally bad efficency of electric heating):
- They have one day of ineratia (they heat only at night and then keep the heat over a whole day). This means if the next day is unusually warm and you forget to switch them off the appartment is overheated the whole day. And in reverse, if you forget to switch them on, you have no way of "adhoc-heat".
- The minimal setting is too hot for the transition seasons (autum, spring).
A colleague pointed me to the nice ESP8266 development board (thanks Ivan!) and with some temperature sensors and a servo it is easy to turn this 15 year old heater into a fancy IoT-device.
First I tried to use the DC control port which is powered by a DC current between 0.9 - 1.4 Volt , but then I ditched that idea because it would have required opening the heater and fiddling with its internals which I didn't want to do (too risky).
The easy workaround was to just turn the max heat knob with a servo.
I 3D-printed the part to hold the servo with a cheap 40€ 3D print pen which uses the normal 1,75mm PLA filament. It doesn't look nice but it does the job. It is connected to the heating with magnets (which I stole from my son's toy box).
The device's casing is way too big. This is the first prototype, so I wanted to have some space to play around. Also I used an additional NodeMCU breakout-board which makes using normal bread-board-connectors more convenient.
I built and flashed the firmware with the Arduino IDE. This folder contains the Arduino IDE ino-file for the device.
The device uses the WifiManager arduino lib (https://github.com/tzapu/WiFiManager). If it cannot connect to a Wifi all LEDs will be on. You then can connect to the devices accesspoint ( look for "cosilino-...) (... == deviceid).
You might have to adjust the mqtt server to your hostname/ip before flashing.
#define MQTT_SERVER "cosilino-gateway"
example for different ip:
#define MQTT_SERVER "192.168.123.33"
I screenshotted all plugins I installed (see doc/arduino_ide_plugins).
- ESP8266 (NodeMCU 1.0)
- Tower SG90 Micro Servo
- DHT-22 Temperature and Humidity-Sensor
- DS18S20 Temperature Sensor
- 1x red, 1x yellow, 1x green LEDs
- 3x 220Ohm resistor (for LEDs)
- 1x 1k Ohm resistor (pullup DHT-22)
- 1x 4,7k Ohm resistor (pullup DS18S20)
- RaspberryPi or any other permanently running pc (for MQTT broker + mongodb)
You find the fritzing file, schematics and plan in doc/fritzing.
I used a raspberrypi with mosquitto and mongodb as backend.
apt-get install mosquitto mongodb-server
You might want to enable mongodb to your internal network by commenting out
/etc/mongodb.conf
#bind_ip = 127.0.0.1
Then restart mongodb (/etc/init.d/mongodb restart)
You can connect to all topics on the broker for debugging purposes.
-v also prints the topic names.
$> mosquitto_sub -v -t "#"
cosilino/171d45/status {"deviceId":"171d45","roomHum":51.80,"roomTemp":22.30,"heaterTemp":-127.00,"heaterPower":0}
For now I didn't implement any awesome logic. I just set up a cronjob to switch the heater on for 1-2 hours at night. In winter it is on all the time anyway and in summer off all the time. Of course a nice automatic adjustment using a weather forecast would be nice (see todo).
Actually the percentage values aren't to helpful. In the end I controled the heat by how long I set the heater to 100% (which is actually 66% as the servo doesn't turn 270° but only 180°).
For me 1-2 hours per night was enough during autum/spring.
$> mosquitto_pub -t "cosilino/171d45/heaterpower" -m 0
$> mosquitto_pub -t "cosilino/171d45/heaterpower" -m 100
Example cronjobs
$> crontab -l
# For more information see the manual pages of crontab(5) and cron(8)
#
# m h dom mon dow command
#0 21 * * * mosquitto_pub -h cosilino-gateway -t cosilino/171d45/heaterpower -m 100
#45 21 * * * mosquitto_pub -h cosilino-gateway -t cosilino/171d45/heaterpower -m 0
#10 1 * * * mosquitto_pub -h cosilino-gateway -t cosilino/171d45/heaterpower -m 100
#30 1 * * * mosquitto_pub -h cosilino-gateway -t cosilino/171d45/heaterpower -m 0
#40 4 * * * mosquitto_pub -h cosilino-gateway -t cosilino/171d45/heaterpower -m 100
#0 5 * * * mosquitto_pub -h cosilino-gateway -t cosilino/171d45/heaterpower -m 0
I just run the backend in screen.
apt-get install screen
screen
./cosilino-backend.py
You might have to install an older version of pymongo as the mongodb version which comes with raspbian is quite old (2.4..) .
The plans to build a shiny webui were there, but for now I just built a minimal gtk interface with mathplot lib.
You might have to install an older version of pymongo as the mongodb version which comes with raspbian is quite old (2.4..) .
./cosilino-draw.py
The real plan was to dynamically set the heat level depending on the next days weather and condition (sun/clouds).
And of course it should be possible to access and control the devices from the phone. So a nice webui should follow.
- add auto tune by getting weather forecast: https://openweathermap.org/
- add mobile-friendly webui
If you are interested in learning more about the heaters specs, have a look at the manual.