Overruling thermostat room and DHW temperature setpoint

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Overruling thermostat room and DHW temperature setpoint

Postby alcindo » Mon Apr 15, 2019 8:52 pm

Hi (Schelte),

Kudo's for the great work!

I have a OTGW (as sold by Nodo-shop) between my Atlantic Loria-duo (v26) and its simple thermostat. (And a second OTGW I use for testing.)
Officially the Atlantic Loria-Duo with the v26 (or earlier) software/hardware does not support OpenTherm.
But as described in https://gathering.tweakers.net/forum/li ... 7#56462237 you can still use the OTGW.

With Domoticz (running on a Raspberry Pi 3) I can plot the room, outside and DHW temperature.
Only overruling the thermostat setpoint fails. I.e. having Domoticz changing the target room temperature on the boiler.
Trying to understand I did some tests and found OTGW, Calenta, Toon and Setpoint override not working.

As I understand it now, the OTGW sends the TT/TC setting to the thermostat.
And unless the thermostat understands the command, nothing happens.
Correct?

So I have several options:
1) Give up, let it as it is. This will cost me money in the long term.
2) Get another smarter thermostat. But I may lose some options. (Such as DHZ boost function.) And it costs money ;-)
3) Hack the thermostat. I think would cost too much time. And I have not found any documentation of others hacking this type of thermostat.
4) Ask for or make some changes to the OTGW firmware "to make it work".

I am looking for two features:
1) Set the target DHW temperature and changing the value sent from the thermostat to the boiler in the OTGW.
2) Set the setpoint / target TC value and changing the value sent from the thermostat to the boiler in the OTGW.
So if the termostat does not accept the value I set via Domoticz (or other tool) it will overrule it.
What I would give up is being able to set it on the thermostat. (Or ideally if/when the TC/TT value is changed on the thermostat this should overrule the Domoticz setting until the next time.)

The way the Loria Duo works, the thermostat only is used to set the target temperature and report the current room temperature. The thermostat does not modulate. Modulation is configured on the boiler itself.

It is not clear to me how much flash memory is left/available on the OTGW to add this. (Or at the moment even where to start.)
So I am wondering if it feasible to make this change in behavior in the OTGW.

You may ask yourself why I would want to do this.
I want the boiler (both DHW and CH) work as much as possible when my solar panels are delivering power.
It is better to use the electricity from the solar panels than to sell cheap (about half price if I am lucky) and buy back later at a higher rate.

Best regards,
Alcindo
alcindo
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Re: Overruling thermostat room and DHW temperature setpoint

Postby hvxl » Thu May 02, 2019 9:01 pm

Unless I misunderstand what you want, the current gateway firmware can already do feature #1 using the SW command. Feature #2 is not implemented.

May I suggest option 5: Use the "interface" firmware. That just reports the messages it receives, and then expects to be instructed what message to send. In most cases the program handling the serial interface to the OTGW can just return the exact same message (with the B or T stripped off) back to the OTGW to pass it on unaltered. But it can also alter the values in the message, or send a completely different one. You just have to write that program in whatever language you like.
Schelte
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Re: Overruling thermostat room and DHW temperature setpoint

Postby alcindo » Wed Jun 12, 2019 4:01 pm

Hi,

Thanks. I will give your suggestion a go.

Best regards,
Alcindo
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