Mapping EMS/ESP32 sensors for SAT

[sergeantd83]

Following this issue #2103, we are doing an initially effort to map the EMS/ESP sensors for SAT usage.

Part I ( Mapping EMS/ESP32 sensors for SAT )

SAT	EMS Sensor	UOM	Read / Write	Description	Mandatory Values
DATA_FLAME_ACTIVE	"burngas"	Binary	R	Whether the flame is ON or OFF	✔️
DATA_DHW_SETPOINT	"dhw/seltemp"	°C	R / W	The DHW setpoint	✔️
DATA_CONTROL_SETPOINT	"selflowtemp"	°C	R / W	The Boiler flow water temperature setpoint	✔️
DATA_REL_MOD_LEVEL	"curburnpow"	%	R	The current boiler power	✔️
DATA_BOILER_TEMPERATURE	"curflowtemp"	°C	R	The boiler flow water temperature	✔️
DATA_RETURN_TEMPERATURE	"rettemp"	°C	R	The return water temperature	✔️
DATA_DHW_ENABLE	"tapwateractive"	Binary	R	When the DHW is in use	✔️
DATA_CENTRAL_HEATING	"heatingactive"	Binary	R	When the thermostat asks for heating	✔️
DATA_SLAVE_MEMBERID	-	Integer	R	The unique number of the Boiler Manufacturer	❌
DATA_BOILER_CAPACITY	"nompower"	kW	R	The Rated maximum power in kW of the boiler	❌
DATA_REL_MIN_MOD_LEVEL	"burnminnpower"	%	R		❌
DATA_MAX_REL_MOD_LEVEL_SETTING	"burnmaxpower"	%	R / W	The maximum allowable power of the boiler	✔️
DATA_DHW_SETPOINT_MINIMUM	-	°C	R	The min value for the DHW setpoint	❌ ( But nice to have )
DATA_DHW_SETPOINT_MAXIMUM	-	°C	R	The max value for the DHW setpoint	❌ (But nice to have)

Part II ( Boiler control )

OTGW Command Payload	EMS/ESP32 Command Payload	Description
await self._send_command(f"CH={1 if state == DeviceState.ON else 0}")	-	The CH command starts / stops the heating
await self._send_command(f"CS={value}")	await self._send_command({"cmd":"selflowtemp","value":0 if value == 10 else value})	The CS command manipulates the boiler flow water setpoint
await self._send_command(f"MM={value}")	await self._send_command({"cmd":"burnmaxpower","value":value})	The MM command manipulates the maximum modulation of the boiler
await self._send_command(f"SW={value}")	await self._send_command({"cmd":"dhw/seltemp","value":value})	The SW command changes the DHW setpoint
await self._send_command(f"SH={value}")	await self._send_command({"cmd":heatingtemp","value":value})	The SH command manipulates the max allowable boiler flow water temperature

Part III ( Command Topic )

OTGW Command Topic	EMS/ESP32 Command Topic
await mqtt.async_publish(self.hass, f"{self._topic}/set/{self._node_id}/command", payload)	await mqtt.async_publish(self.hass, f"ems-esp/<base>/boiler", payload)

Part IV ( Publish Topic )

OTGW Publish Topic	EMS/ESP32 Publish Topic
OTGW/value/{self._node_id}	ems-esp/boiler_data

[proddy]

Could you add the unit of measure (uom) and a description of the SAT name? That will help us locate the EMS variant. Some of the names are very ambiguous, like "DATA_CENTRAL_HEATING" ? Also tapwateractive and heatingactive are not native EMS values as they are calculated by the EMS-ESP software based on boiler states, heating type and current flow temperatures, and not 100% accurate. So we may need to find alternatives if this is essential for SAT.

[proddy]

@MichaelDvP will need your wisdom here too as it progresses

[MichaelDvP]

Edit the table:
DATA_FLAME_ACTIVE "burngas" Binary R Whether the flame is ON or OFF ✔️
DATA_DHW_SETPOINT "dhw/seltemp" °C R / W The DHW setpoint ✔️
DATA_CONTROL_SETPOINT "selflowtemp" °C R / W The Boiler flow water temperature setpoint ✔️
DATA_REL_MOD_LEVEL "curburnpow" % R The current boiler power ✔️
DATA_BOILER_TEMPERATURE "curflowtemp" °C R The boiler flow water temperature ✔️
DATA_RETURN_TEMPERATURE "rettemp" °C R The return water temperature ✔️
DATA_DHW_ENABLE "tapwateractive" Binary R When the DHW is in use ✔️
DATA_CENTRAL_HEATING "heatingactive" Binary R When the thermostat asks for heating ✔️
DATA_SLAVE_MEMBERID Integer R The unique number of the Boiler Manufacturer ❌
DATA_BOILER_CAPACITY "nompower" kW R/W The Rated maximum power in kW of the boiler ❌
DATA_REL_MIN_MOD_LEVEL "burnminnpower" % R / W ❌
DATA_MAX_REL_MOD_LEVEL_SETTING "burnmaxpower" % R / W The maximum allowable power of the boiler ✔️
DATA_DHW_SETPOINT_MINIMUM 30 °C R The min value for the DHW setpoint ❌ ( But nice to have )
DATA_DHW_SETPOINT_MAXIMUM 60 °C R The max value for the DHW setpoint ❌ (But nice to hav

For DATA_DHW_SETPOINT we have also "dhw/settemp", readonly. This could be lower then dhw/seltemp if solar is active and wants to prevent dhw charging from boiler. But for controlling dhw/seltemp is right to read and write.
"tapwateractive" and "heatingactive" are calculated by ems-esp, but should work for all boilers.
For DHW there are flow systems, showing "tapwateractive" if there is flow and burner is on, for buffer systems "tapwateractive" shows charging of the dhw buffer (with burner on).
For DATA_BOILER_CAPACITY we have "nompower", but not published by all boilers. Also sometimes it is the power for dhw charging sometimes for heating. We have it editable.
DATA_DHW_SETPOINT_MAXIMUM is "dhw/maxtemp" for some boilers, but often not published.
burnminpower, burnmaxpower are only writeable for modulated boilers, otherwise fixed. I'm not sure how 2-stage burners handle burngas, maybe they switch to burngas2, maybe both are set.

[sergeantd83]

@MichaelDvP, @proddy thanks!
I added a Part II table in the original post about how we control the boiler. Is it helpful to match the commnads you send to the EMS gateway?

[proddy]

I prefer not to add more code to ems-esp and to adjust the SAT python code which is a Home Assistant add-on, or even better do a specific fork that doesn't use OpenTherm at all. The only logic we need is the self-learning heating curve.

[sergeantd83]

I prefer not to add more code to ems-esp and to adjust the SAT python code which is a Home Assistant add-on

Ok that was the original idea. I just asked because @MichaelDvP kindly offered.

or even better do a specific fork that doesn't use OpenTherm at all.

We don't care to create an "EMS-SAT"fork. Because SAT is a universal controller and an on-going development. It not our intention to maintain 2 repositories.

The only logic we need is the self-learning heating curve.

Probably you misunderstood SAT. The heating curve calculation is only one of the ongoing calculations and actually the easiest one. The hard part is the boiler control in the most efficient way while respecting the heating system limitations.

[Delta1977]

That would be a great addition to Ems-esp. I hope the implementation is going well—I can’t wait to try it out. I’d also be happy to be a beta tester!

[MichaelDvP]

I just asked because @MichaelDvP kindly offered.

Yes, ems-esp has a lot of code and special entities to adapt to the dump HA climate widget.
So i assumed that we can add a few lines to allow the different command format for the more powerfull SAT.
Sorry if i have promised too much.

[sergeantd83]

No worries, our job is to create the EMS coordinator without mistakes 🙂. Yesterday we worked with @Alexwijn and I think we finished the mapping. Can you please review the tables in the original post if they are correct? It will be a huge help since we can’t test anything.

Thanks again for your help!

[proddy]

@MichaelDvP we need your expertise here. On Discord there was a discussion on how the SAT would send the commands similar to the OpenTherm GW which uses heating on/off and setpoint values. I explained in EMS the boiler will only except a new setpoint temperature value if it's lower than the actual current heating temperature, which is why we have the forceheatingoff command to send 0's every minute. So for SAT to work with EMS-ESP this Setting needs to be enabled and SAT only needs to send MQTT topics ems-esp/boiler/selflowtemp.

Is this a correct understanding?

@sergeantd83 mention also

OTGW intercepts the Thermostat messages and prioritizes the published commands. When there is not a new command for 60 seconds then falls back to thermostat operation. With this solution we can have a back up OT thermostat while SAT controls the heating when network and HA are up and running.
CS=temperature
Control Setpoint — Manipulate the control setpoint being sent to the boiler. Set to 0 to pass along the value specified by the thermostat. To stop the boiler heating the house, set the control setpoint to some low value and clear the CH enable bit using the CH command. A CS command with a value of 8 or higher must be repeated at least every minute as long as adjustment is needed. This is a vigilance check to prevent runaway heating in case the controlling program loses its connection, or crashes.
Warning: manipulating these values may severely impact the control algorithm of the thermostat, which may cause it to start heating much too early or too aggressively when it is actually in control.
Examples: CS=45.8, CS=0

[sergeantd83]

forceheatingoff overrides any selflowtemp setting, so has to be off to control the boiler.

Thanks for the confirmation. It is included in the commands list.

I don't know if a low selflowtemp value like 8°C is possible. Someone without thermostat have to check.

We use this logic for the selflowtemp command.

You can't use SAT or direct boiler control if a ems(+)-thermostat is connected. The thermostat will overwrite the any selflowtemp setting.

Who knows, you may found a solution for EMS/ESP32 firmware to intercept the thermostat messages to the boiler. Then SAT can work on top of an existing EMS thermostat 😄.

Thank you very much for the information. @MichaelDvP and @proddy, without your help, the EMS coordinator would have been impossible.

[csutcliff]

I don't know if a low selflowtemp value like 8°C is possible. Someone without thermostat have to check.

My HT3 system will accept down to 11°C. Writing 10°C or below it goes to 0°C instead.

@sergeantd83 is DATA_RETURN_TEMPERATURE completely mandatory? Some boilers (mine included) do not have the "rettemp" available.

If it is absolutely required, could it be provided by a temp probe stuck to the return pipe? These sensors are natively supported in EMS-ESP so it would just need some setting to choose the correct sensor.

[sergeantd83]

It is not necessary to have this value reported. SAT can handle the calculations without this value. We are also working on a new feature to dynamically change the selflowtemp based on the boiler flow water temperature, a feature that will be quite beneficial for boilers that don’t report the return water temperature and TRVs are installed.

[MichaelDvP]

@sergeantd83 You have set return temp as mandatory, but some bosch boilers does not have a sensor connected. In this cases rettemp is missing in publish payload. If SAT needs it to work, could there be a fallback to a DS1820 temperaturesensor? We could advice users to connect a DS1820 and name it rettemp, then it is published with topic temperaturesensor_data, payload as normally in boiler_data: {"rettemp":xx}

Also possible: we can use custom entities in RAM (topic custom_data, payload {"rettemp":xx} with fixed names and users have to create on-chang-schedules to fill them with values.

[sergeantd83]

That would be a great addition! Then SAT will be able to monitor the return temperature here. This is the true power of open source and cooperation.

[proddy]

@MichaelDvP do you know if we can get the minimum power from the boiler that it needs to modulate? Like we do with nompower for the maximum power. We get the min and max from x04/UBAFactory and use this to set the min/max range for burnMaxPower but I think that is a % and not a kW, although we can convert it.

[sergeantd83]

We need this value in % not kW. So the min value from x04/UBAFactory is just fine.

[MichaelDvP]

telegram 0x04 is not implemened in all boilers.
The actual boiler setting is burnMinPower from telegram 0x16(ems) or 0xE6(ems+).
It's also in percent.

[csutcliff]

This also needs to be able to be manually set. My boiler reports 0% as the minimum but in actuality it can only go down to 30%

[proddy]

Same with my Nefit boiler. burnMinPower value is 0, unless manually set, and the actual min power is from the UBAFactory telegram which shows a value of 23 (%) which also matches the min value in the boiler's manual.

[MichaelDvP]

Then i think we have to add an entity for factoryMinPower from 0x04.
My burner is single stage oil and the boiler could be equipt with different burner types, so there is no nompower.
In 0x04 i have min=100%, max=100%, nompower=0 and indeed burnMinPower from 0x16 is 0.
I don't know what burnMinPower is used for, i thought it was the min setting, but i was wrong.