Sniff Saunier Duval's remote thermostat signals for weather station


Let's see if you can provide some light on this...

I'm trying to build a home sensor network. I've started with temperature and humidity, which get read from several Oregon Scientific sensors by and Arduino with a 433Mhz receiver, and then the values are sent to a DB hosted in a Raspberry Pi.

So far, so good. I found a lot of info in this forum and elsewhere to do this bit. Now the difficult part:

I want to be able to:
1.- Know if the heating is on or off
2.- Know what temperature the remote thermostat is setting

My home has a Saunier Duval Isofast F35 boiler, with a remote thermostat.

As far as I've been able to find out, the remote thermostat uses a frequency of 868MHz to send its commands. I've also read that it uses the EBUS protocol, but I'm not sure how that works over the air (if at all). I'm quite lost at this

I cannot hack the boiler (rented apartment). So I thought that the best way to solve 1 and 2 above was to read the 868MHz signals and decode them. But so far I have not found a way to do it, or more importantly, anyone that has done it before.

I'm looking for ideas on how to do 1 or 2 above. Either by decoding the 868 signals, or otherwise.

Thanks in advance, and if anybody wants more details on what I'm doing, I'll post some more data

Thats an interesting idea. I had a similar idea once but it didnt go anywhere due to lack of info.

I assume that you've tried the user manuals without success? (Saunier duval ISOFAST CONDENS F 35 E Manuals | ManualsLib) This page has info on EBUS EBUS (serial buses) - Wikipedia

The rtl-sdr project and Gnu radio might be good places to start if you wish to attempt to sniff and reverse-engineer the wireless protocol- these are $20 USB sticks sold as TV tuners but can be re-purposed for a wide range of things. Also this page links to one guy's efforts to decode an unknown signal, probably worth a read for the steps he took.

You may be able to sense the boiler running by other means- the sound of the fans running or temperature of the outlet perhaps?

Sensing the set-point might be harder as I imagine that information stays in the thermostat and only on/off commands are sent to the boiler (but I could be wrong..)

Yes, i tried the manuals, with no luck. I did not know about the rtl-sdr project you mention, so I'll have a look, although it may prove too complex for me at the moment.

I did think about listening to the sound of the fans. However, since the boiler also provides domestic water, it makes noise also when I open the hot water...

Will keep trying, and open to new ideas from the forum!


using a temperature sensors on an outgoing pipe gives you the temperature of the outgoing water.

If it is rising, the boiler is (switched) on
If it is stable and high the boiler is on
If if is falling, the boiler is (switched) off
if it is stable and low the boiler is off

If you use two sensors a distance D apart you can measure the flow (approx)
if you read sensor A in a tight loop and when it rises (TIMEA) you start reading B in a tight loop.
When that rises [TIMEB] the warm water passed both sensors

speed = D/ (TIMEB-TIMEA);

Hi Albertop,

If you have already got the Oregon Scientific siganls worked out you may be interested in my "pseudo" OS sensors that you could easily attach to the heating system without voiding warranties/leases/bonds etc and monitor the activity of the central heating yourself??

Make your own OS sensors

and then integrate that into your monitoring/control system??

Cheers, Rob

OS WS + Arduinos

Apologies for the long delay in replying. Haven't been able to get enough time to hack my system until now

robtillaart, thanks a lot for your reply. I have implemented this today as a prototype, and it works great. I've used a moteino board with a DS18B20 temp sensor. This sends the outflow pipe temperature to another moteino gateway and finally stored in a Raspberry Pi. I am now testing it to see the pattern and convert temperature changes to heating ON or OFF. But it looks very promising.

robwlakes, I've gone through your site and it is very interesting. I had the moteinos already so I went that route, but I may change that in the future using your guide, so that I have only one Arduino gateway.

Thanks for your replies and I'll get on working

... I'll get on working

Please keep us informed of the progress and if possible share your code :slight_smile:

I am curious why the arduino can be only used to read ebus ?

can you share a simple trace for curiosity