I am waiting for the Heat demand implementation on the firmware to compare what the OT Bridge is sent. At the moment I dont think Domoticz is tracking the correct value, largely driven by the fact that Dan doesn't have an OT Bridge. My biggest worry is that there doesn't appear to be a great deal of RF chatter between the controller and the OT Bridge. It almost appears that the OT bridge reads all the messages flying around and decides what to do without the controller telling it. But am not entirely sure too.
OpenTherm control behaviour
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I very much doubt that's happening. Given the relative location of a couple of my HR92s and my OT Bridge, I don't think they'll be able to hear each other.
When you say "there doesn't appear to be a great deal of RF chatter", how are you gauging that? Remember that the firmware we're running on the radios doesn't parse OT messages very well, so you won't see them at all in the Evohome logs unless you're looking for parsing errors. (Oh, unless you're using an HGI80? I can't remember.)
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Originally posted by bruce_miranda View PostI have an HGI80.
Is this what you see ?
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I suspect that a BDR91 boiler relay and an OT Bridge are effectively working off the same signal from the controller.
The only difference is how they deal with anything less than 100% heat demand. With the BDR91 it's by pulsing the boiler on and off, whilst with the OT bridge it's by passing the relative heat demand through to the boiler. The controller doesn't micro-manage either device.
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Originally posted by paulockenden View PostI suspect that a BDR91 boiler relay and an OT Bridge are effectively working off the same signal from the controller.
The only difference is how they deal with anything less than 100% heat demand. With the BDR91 it's by pulsing the boiler on and off, whilst with the OT bridge it's by passing the relative heat demand through to the boiler. The controller doesn't micro-manage either device.
I really must find the time to figure out why my radio firmware can't receive the messages from the OT bridge (I suspect a timing issue), fix it and then get some OT messages over to DanD for analysis.
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DanD has a lot of OT messages from me already which he has looked at. But there is definitely an issue with the implementation or interpretation of the OT Bridge and Domoticz. Currently my OT Bridge Heat Demand messages seem to track those of my Kitchen zone. Which is the only zone in the house which used a BDR91/TR87 combination for an UFH zone. The thing is I have a Boiler Device and an CH Valve Device too, but I have neither of those two as BDR91s. I suspect this is all wrapped up in the issue with the various heat demand messages from the BDR91 and how Domoticz is currently reading them.
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Originally posted by fergie View PostCould it be as simple as the BDR telling the boiler to turn on or off where as the OT tells it turn the temp up or down? If it’s not specifying an exact temp, would explain a few things.
P.
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