Opentherm Gateway

This Forum is about the Opentherm gateway (OTG) from Schelte

Moderator: hvxl

Opentherm Gateway

Postby fabian » Sat Feb 25, 2012 11:17 pm

So far this gateway has only been discussed in the Homeseer script forum, but while there is a new 'Hvac Heating Opentherm' forum, I think it's time for a new thread regarding the hardware.

Documentation, design, software: http://tclcode.com/opentherm/
More technical details: http://home.xmsnet.nl/openthermprotocol/
Homeseer script: Opentherm gateway and script integration into Homeseer by blb

Known supported central heating units: Remeha Avanta, Intergas combi compact cw4/cw5, Intergas prestige cw6

Functions:
    Forward OpenTherm messages between the thermostat and the boiler
    Report about the messages on the serial interface
    Change the thermostat setpoint
    Set the clock of the thermostat
    Send the outside temperature to the thermostat
    Control the domestic hot water option of the boiler
    Obtain additional information from the boiler

The gateway has been primarily designed for a Remeha Avanta heater with a Honeywell Chronotherm Modulation thermostat. With a lot of help it's now also perfectly communicating with Intergas heaters.

Intergas seems to have issues with encoding the messages in Manchester code when the flame is on or the pump is running. For the gateway to still decode messages and send messages during this time, it has to be less accurate then the Openthem Specification describes. There is a custom gateway firmware available for this.

My gateway has been running stable now for a week so it's time to round things up and mount it on the wall.

IMG_3881_mod.jpg
4 Status leds
IMG_3881_mod.jpg (46.21 KiB) Viewed 21643 times

IMG_3882_mod.jpg
Gateway in its enclosure. Leds glued.
IMG_3882_mod.jpg (79.72 KiB) Viewed 21643 times

IMG_3883_mod.jpg
LEDs side view.
IMG_3883_mod.jpg (57.59 KiB) Viewed 21643 times

IMG_3917_mod.jpg
Gateway + Intergas
IMG_3917_mod.jpg (60.46 KiB) Viewed 21643 times


Red = Opentherm Error
Yellow = Flame ON
Green / Green = Opentherm Messages
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Re: Opentherm Gateway, DomotiGa support

Postby BreFra » Sun Feb 26, 2012 1:56 pm

For everyone who is using DomotiGa,

I build this gateway myself and I am currently writing the code to connect this gateway to my DomotiGa system.
At the moment I'm figuring out the best way to expose the OpenTherm information to DomotiGa (devices).
As soon as I have a good working concept I'll share it with Ron and rest of the DomotiGa community.

So DomotiGa support is on its way :D ....
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Re: Opentherm Gateway

Postby wwolkers » Mon Feb 27, 2012 12:24 pm

Did you make the PCB yourself? I can't find any eagle files for the PCB on the mentioned site.
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Re: Opentherm Gateway

Postby Freemann » Mon Mar 19, 2012 9:37 am

Could this work with a Vaillant (OpenTherm compatible) and Honeywell Vision Modulation?
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Re: Opentherm Gateway

Postby hvxl » Mon Apr 09, 2012 1:43 pm

While checking the backlinks to my Opentherm Gateway web page (http://www.tclcode.com/opentherm), I found quite a few references from this site. So I thought it may be time for me to chime in.

The eagle files are included in the source code package that you can request via the web site. However, the PCB design for the current version of the gateway was intended for building the circuitry on perf board, not really for a proper PCB.

I am currently working on a new design with someone else interested in building the device. He has ordered a batch of 10 professionally made circuit boards. Once I'm confident the new design is working correctly, I will make the gerber files available for download so people can easily order their own batch.

A few planned improvements of the new design are:
  • Galvanic isolation of the boiler interface
  • Loading firmware updates via the serial interface
  • Header for connecting the LEDs
  • Header with two I/O pins that can be used to connect an outside temperature sensor, for example

Chances are quite good that the gateway will work (or the firmware can be tweaked to make it work) with a Vaillant boiler and a Honeywell Vision Modulation thermostat.
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Re: Opentherm Gateway, DomotiGa support

Postby sj3fk3 » Mon Apr 23, 2012 9:39 pm

BreFra wrote:For everyone who is using DomotiGa,

I build this gateway myself and I am currently writing the code to connect this gateway to my DomotiGa system.
At the moment I'm figuring out the best way to expose the OpenTherm information to DomotiGa (devices).
As soon as I have a good working concept I'll share it with Ron and rest of the DomotiGa community.

So DomotiGa support is on its way :D ....


I'm wondering what the status of this project is... I just bought a Remeha Calenta (with iSense) and was thinking about what would be the best way to get some data out of it (and posible also into it :-) and from what I've seen so far Domotiga looks like the best solution for Linux. It would be great if I could use it to control both the radiators (via the ELV max! system) and the Remeha via a OpenTherm gateway (maybe on a arduino?).
Kind Regards,
Greg.
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Re: Opentherm Gateway

Postby BreFra » Tue Apr 24, 2012 9:22 pm

As requested a short status update:

I currently have a working concept based on 4 DomotiGa devices. The themostat device shows the current setpoint but also allows to override the setpoint.
The other devices contain the other OpenTherm info like: water pressure, flame status, burner counters, outside temperature.

I'm still bussy fine tuning and testing the code. I expect to finish this within a few weeks...
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Re: Opentherm Gateway

Postby RDNZL » Wed Apr 25, 2012 2:40 pm

Nice work!
I like projects like this that are a mix of soldering electronics, Linux and DomotiGa :D
Regards, Ron.
http://domotiga.nl - open source home automation software for Linux.
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Re: Opentherm Gateway

Postby sj3fk3 » Wed Apr 25, 2012 9:26 pm

Just thinking out loud: Wouldn't it be great if the guys from http://www.rfxcom.com/ made an rf version of the (not)Opentherm Gateway? For me that would be the ultimo solution... and possibly their next step to TWD.
Kind Regards,
Greg.
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Re: Opentherm Gateway

Postby Digit » Wed Apr 25, 2012 11:44 pm

The Walking Dead, Total World Domination or Total World Destruction? :)

You mean like adding a RF transceiver to the OT gateway and transmitting all the output?
With OT you have 2 32-bit frames each second, for transferring those I would personally prefer a wired solution.
IMHO if you really want this done the RF way, I would add some additional local processing and only transmit changes, to minimize RF traffic.
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Re: Opentherm Gateway

Postby sj3fk3 » Thu Apr 26, 2012 7:10 am

Total world domination of course :-)

Good point about the traffic! Ok, this needs more thought...
Kind Regards,
Greg.
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Re: Opentherm Gateway

Postby RDNZL » Fri May 18, 2012 2:48 pm

Update:
DomotiGa support for this home-built gateway has been coded and shared by user BreFra, I have merged his code with DomotiGa version 0.1.206 and it's just committed.
Thanks a lot for your work!
Regards, Ron.
http://domotiga.nl - open source home automation software for Linux.
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Re: Opentherm Gateway

Postby FoRMaTC » Thu Jun 07, 2012 2:17 pm

Hi Guys,

I'm not a techie with a soldering iron so is there anyone who is selling these kind of OT Gateways to monitor my AWB 3HR?

Cheers,

Bjorn
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Re: Opentherm Gateway

Postby FoRMaTC » Thu Jun 07, 2012 11:24 pm

I found out that there are some ppl willing to help me out.
The funny part is that they are collegues of mine :-)

Anyhow, i need to order some PCB's.
According to the website (http://www.tclcode.com/opentherm/pcb.html) this can be done with batches of 10.
Anyone willing to buy some?
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Postby Rene » Fri Jun 08, 2012 7:12 am

Count me in for one.
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