Long story short (for people that would look for the same thing as I did):
Evohome with the Opentherm R8810A1018 cannot control DHW.
Only the DHW kit allows Evohome to control DHW.
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Hi all,
I've just had my Evohome setup installed.
Initially, the installer went the BDR91 route, considering my boiler was not (officially) supporting Opentherm protocol.
It ment changing the wiring between the controler to the Boiler (as the Boiler was previously controlled by a single programmable Thermostat) to control it with the plain relay on/off.
Full disclosure, the Boiler is an Atlantic Perfinox 4100 (yup, I'm from France).
This Boiler is actually built around an LMU64 from Siemens, and was previously controlled by an QAA73.110 (also from Siemens).
It turns out that those two elements are actually talking to each other using Opentherm. This is their design.
I then assumed that it shouldn't be an issue to switch back to a Opentherm mode, and ordered on my own the R8810A1018 Evohome Opentherm controller, and installed it "manually".
Turns out I was actually right, it works flawlessly since then.
Modulation is done properly, and thanks to the new firmware that I've requested to Honeywell (.17 instead of an old .11), it is confirmed by the Evohome controller.
However, my question is actually regarding the DHW.
Previously, the QAA73.110 was able to handle some parts of the DHW management (not much more than plain 'activate' DHW or 'de-activate' DHW.)
Since moving back to the Opentherm management of the Boiler, the Boiler disabled itself the Heating logic (Flow control, CH temperature, Daily Programmation, ...), but kept the DHW management internally.
The Evohome shows nothing regarding the DHW, and everything needs to be done at the Boiler directly.
It feels a bit strange, considering that the Opentherm IDs that the QAA73.110 & the LMU64 are supposed to handle include the DHW, and same goes for the Evohome + R8810A.
In theory, the R8810A controls the ID #26 (DHW Temperature), similar to the QAA73.110, and the LMU64 should be able to execute the command sent by the Thermostat (wether it is R8810A or QAA73.110).
Does any one of you, having a combined boiler (Heating + DHW internal storage), have their DHW managed by Evohome ?
Or, on the opposite, does Evohome only handle DHW with the "DHW kit" ?
I've ordered the components to assemble an Opentherm Gateway to inspect the traffic between the R8810 and the boiler controller to try and confirm the situation, but I'd love to have other feedbacks from what to expect.
Some of the specs sheets of the components:
LMU64 : https://be.elco.net/sites/be.elco.ne...(20031226).pdf
QAA73.110 : https://be.elco.net/sites/be.elco.ne...(20031226).pdf
Opentherm IDs handeled : http://otgw.tclcode.com/matrix.cgi#thermostats
Evohome with the Opentherm R8810A1018 cannot control DHW.
Only the DHW kit allows Evohome to control DHW.
---
Hi all,
I've just had my Evohome setup installed.
Initially, the installer went the BDR91 route, considering my boiler was not (officially) supporting Opentherm protocol.
It ment changing the wiring between the controler to the Boiler (as the Boiler was previously controlled by a single programmable Thermostat) to control it with the plain relay on/off.
Full disclosure, the Boiler is an Atlantic Perfinox 4100 (yup, I'm from France).
This Boiler is actually built around an LMU64 from Siemens, and was previously controlled by an QAA73.110 (also from Siemens).
It turns out that those two elements are actually talking to each other using Opentherm. This is their design.
I then assumed that it shouldn't be an issue to switch back to a Opentherm mode, and ordered on my own the R8810A1018 Evohome Opentherm controller, and installed it "manually".
Turns out I was actually right, it works flawlessly since then.
Modulation is done properly, and thanks to the new firmware that I've requested to Honeywell (.17 instead of an old .11), it is confirmed by the Evohome controller.
However, my question is actually regarding the DHW.
Previously, the QAA73.110 was able to handle some parts of the DHW management (not much more than plain 'activate' DHW or 'de-activate' DHW.)
Since moving back to the Opentherm management of the Boiler, the Boiler disabled itself the Heating logic (Flow control, CH temperature, Daily Programmation, ...), but kept the DHW management internally.
The Evohome shows nothing regarding the DHW, and everything needs to be done at the Boiler directly.
It feels a bit strange, considering that the Opentherm IDs that the QAA73.110 & the LMU64 are supposed to handle include the DHW, and same goes for the Evohome + R8810A.
In theory, the R8810A controls the ID #26 (DHW Temperature), similar to the QAA73.110, and the LMU64 should be able to execute the command sent by the Thermostat (wether it is R8810A or QAA73.110).
Does any one of you, having a combined boiler (Heating + DHW internal storage), have their DHW managed by Evohome ?
Or, on the opposite, does Evohome only handle DHW with the "DHW kit" ?
I've ordered the components to assemble an Opentherm Gateway to inspect the traffic between the R8810 and the boiler controller to try and confirm the situation, but I'd love to have other feedbacks from what to expect.
Some of the specs sheets of the components:
LMU64 : https://be.elco.net/sites/be.elco.ne...(20031226).pdf
QAA73.110 : https://be.elco.net/sites/be.elco.ne...(20031226).pdf
Opentherm IDs handeled : http://otgw.tclcode.com/matrix.cgi#thermostats
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