Tuesday, June 23, 2009

Heating system rundown

Recently I met one of the persons behind the Wattcher, a nice little device to measure the electricity consumption of the house and show it in an accessible way to the users. Furthermore, it is a design piece as it was designed by the famous dutch designer Marcel Wanders.
Talking about the wattcher and my own power ball, I mentioned by automated heating system, and he was interest in it, so I wrote an extensive email about it, which I think should come here to the blog as well. So here it is, slighly adapted for the bolg:

Here is a quick breakdown of how my system works.
First, in Holland, the central heating works by having a thermostat in the living room which commands the boiler to burn gas when heat is needed. The remaining rooms then keep a temperature which is relative to the temperature in the living room, since the radiators in those other rooms will be more or less opened depending on the wishes of the inhabitants.
Some places have thermostatic valves, in which you can set the desired temperature and it will open and close the radiators according to the need of heat. However, for this last setting to function it is necessary that the living room thermostat turn on the boiler time enough for the heat to get there, and at the necessary moments.

This situation always annoyed me, since to get some decent temperature in the sleeping room in the morning, the living room would have to be heated up in order for heat to circulate in the system and heat up the sleeping room. The same for e.g. the bathroom.

So, I thought of a system where each room would have its own thermostat, able to request heat from the boiler (turn it on) and ways of opening and closing the radiator valves.

These systems are not new, and they exist for office buildings, high end residential buildings, and in other countries where the standard central heating system works according to different principles. Companies like Honeywell also have similar packages, but they are very expensive.

So, I found these room thermostats and radio controlled valve actuators, in elv.de


These are room thermostats, and function just like a thermostatic valve (like mentioned above), but one that you can program the day/night cycle. Furthermore, these thermostats can communicate with another device from ELV:


which is a device to connect to a computer and that receives state data from the thermostats.

So, I got all these together, and built a computer system which receives desired and current temperature data from the thermostats and decides if the boiler needs to be on or not. If the boiler needs to be on (somewhere there is need for heat in the system) the system turns on a relay switch (also a wireless switch from ELV) that turns the boiler on.

I hope I didn't make it very confusing.

Meanwhile, ELV developed a device that does essentially the same:


Monday, June 15, 2009


I just bought a couple of JeeNodes from JeeLab, the Lab behind bringing affordable wireless technology to the arduino! It is not mainstream yet, in fact I think only a couple have been built and sold, but I think it is great simple technology!

So I got my kits, 2 boards, with all the necessary components, and assembled it. The Atmega168 that comes in it already has the arduino boot code burnt in it, along with a demo of the RFM12 radios for test purposes.

To interface with the little JeeNodes a FTDI interface cable (?) is necessary, but since I didn't have one, I remembered that the Arduino can function as a serial data relay when the Atmega is not there, so I connected the jeenode to the Arduino. Only 4 cables: GND, Power, RX and TX. I guess you could only connect the reset, but I couldn't figure that out, so I left it out.

My plan is then to burn the images using the arduino and then transfer the Atmega to the JeeNode board.

Plugged it in, only one, and I could communicate with it. Checked both, and both work!! great little boards, kits and service from JeeLab!

now I still have to solder the antennas (forgot those) and the headers (was too much in a rush to get it running) and then start playing with these little devices.

I am even happier since I think one can connect 8 inputs to it. I thought it was only four. So I can make my little remote weather station, with wind speed sensor, light sensor, temperature, humidity (maybe these can even get in through the TWI) and if I am lucky wind direction sensor.

Thursday, June 4, 2009

Touchatag success

Some time ago I bought a touchatag, not to use their service, but because it is a pretty cheap RFID system.
I always wanted to experiment a bit with RFID and maybe try to get the garden door, the one from the street to the garden to open when we get there with the bike. I know a bit (not much) about the security risks of RFID and so I am weary of using t for any major goal. I figure that if a crook goes all the way to break into my system to unlock the garden door, which is pretty easy to jump anyway, it is probably not a standard lock that is gonna stop him.

So, I got it, tried to get it running with the RFIDIOt tools, but with no major success. But today I found a page saying that you must supply a certain parameter in order to get it to use the proper reader. So I came home, tried it and SUCCESS! I manage to read the tags! now I just have to find some sort of daemon to notify an application that a tag haas been brought into, or out of, contact. It must exist so I'll keep searching!