I've posted about my issues trying to get my E32S (Rinnai/Atag) to work with OpenTherm which it claims to support (though I think it's in the moderation queue). Looking at Dutch forums it may not be possible.
It got me thinking about alternatives to try to modulate the flow - the boiler allows an external thermometer to be connected and has parameters to control a curve allowing the external thermometer to control the flow temperature (ie so when it's warm outside the flow temperature will be lower as we expect there to be less heat demand). Obviously this isn't quite as good as a genuine opentherm connection.
The manual contains expected resistance readings for the temperature sensor at different temperatures, and I wondered whether it might be possible to use a digital potentiometer (controlled by arduino/raspberry pi etc) to provide a fake outdoor temperature reading, and thus indirectly control the flow temperature (as the curves to use are also printed in the manual)
Has anyone tried anything like this? Am I being silly?
My main issue with this plan is that I have no way of easily knowing what the heat demand is at any given moment - though I gather this can be read from the Evohome protocol as it goes over the air (using HGI80 or a homebrew version).
I have experience with ESP8266s so I'd intend to try something with one of those, but would be grateful for any suggestions/advice. Obviously if it works I'll publish details! (though it would probably only be relevant to people with modulating boilers that don't support OpenTherm properly/at all)
It got me thinking about alternatives to try to modulate the flow - the boiler allows an external thermometer to be connected and has parameters to control a curve allowing the external thermometer to control the flow temperature (ie so when it's warm outside the flow temperature will be lower as we expect there to be less heat demand). Obviously this isn't quite as good as a genuine opentherm connection.
The manual contains expected resistance readings for the temperature sensor at different temperatures, and I wondered whether it might be possible to use a digital potentiometer (controlled by arduino/raspberry pi etc) to provide a fake outdoor temperature reading, and thus indirectly control the flow temperature (as the curves to use are also printed in the manual)
Has anyone tried anything like this? Am I being silly?
My main issue with this plan is that I have no way of easily knowing what the heat demand is at any given moment - though I gather this can be read from the Evohome protocol as it goes over the air (using HGI80 or a homebrew version).
I have experience with ESP8266s so I'd intend to try something with one of those, but would be grateful for any suggestions/advice. Obviously if it works I'll publish details! (though it would probably only be relevant to people with modulating boilers that don't support OpenTherm properly/at all)
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