Wow, you have great thermal efficiency on such a low temperatures.
My setup produces 21.5 degrees at boilers 27-33 (+3…7 outside)
GitHub - Joparmen/diyless-opentherm-ota: OTA addition to diyless opentherm for home assistant here you go. This is the sketch I am using btw, maybe you could take a look why I am not capable of reading flame status, modulation, …
I use a wemos D1 mini btw
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Hi there!
I recently got the thermostat working but im very intrested in the eco mode that shuts the boiler down completely. but how would one go on implementing that? Im using the DIYLess sketch for home assistant on a wemos D1 mini with the esp8266 thermostat shield from DIYLess.
Anyone has a solution for the following problem: my boiler stops when the temperature reaches a certain target. Most thermostats work with a tolerance. How can I implement this in the code?
Secondly I would like to choose my temperature according to the moment of the day. In the morning a high system temperature is good to warm up the house, in the evening I prefer it to raise the temperature with low system temperature with gas. How can I do this?
The cause was bad soldering. I can see three parameters now current boiler temperature, target, flame status
Does anybode know what you can do with these
// setpoint topic
const String SETPOINT_OVERRIDE_SET_TOPIC = BASE_TOPIC + “setpoint-override/set”;
const String SETPOINT_OVERRIDE_RESET_TOPIC = BASE_TOPIC + “setpoint-override/reset”;
Great you have resolved your problem with soldering.
Setpoint_override topics are for manual setting boiler temperature bypasing internal PI algorithm. Ive used that for some internal testing and needed some times to set constant heating water temperature.
Do you know how I could set a tolerance?
For example setpoint 21
Boiler starts at 20,7 with heating
Boiler stops at 21,3
Hi All,
I have adjusted my repository to add support for the cv water temperature setting
@shcherban could you also add these changes to the general repo?
There is no tolerance, PID calculates heating water temperature depending on room temperature.
At least it should.
I have twin opentherm boilers in a cascade arrangement. Either or both can be used. How would I drive them both from these DIY devices from the same EvoHome or Nest thermostat? I’m assuming I can’t connect them just in parallel.
My thought are I need one slave that the Thermostat connects to and this is passing same commands to two master devices, one for each boiler? Initially I’m OK with the boilers sharing the same commands but later in the warmer months I would like to be able to alternate which boiler is used to heat. I think I’m comfortable with altering the code myself to achieve this.
Am I on the right track as I’ve never used opentherm before? Slightly confused by the published info that says the slave units are receive only… surely they transmit too when polled.
One other question - is code available for a slave that emulates a boiler such that I can connect EvoHome or Nest and observe the data interchange of the system with an emulated boiler and modify things in between if needed? Do I need two slaves for this ?
We meant that you can not control boiler with slave, because it should be polled. Maybe bad wording.
Nope, we have no good example for that yet, you should develop your own or ask community, i think some people here used a setup with existing thermostat and slave.
I think you can share commands between two boilers for simplicity, but it would be smarter to fully emulate boiler with slave and then decide by yourself how much heat actually you’ll need and turn on one or both.
If you’re using one room thermostat at a time you need one slave for it. And two masters if you have two boilers.
For start it might be better to use gateway (master+slave), and attach slave to EvoHome/Nest and master to your real boiler to see real commands and responses, that would simplify boiler emulation engineering. And for that we have a sample, which just passes commands back and forth and prints them to Serial.
That’s quite a bit of code to create though….
This approach sounds much easier although somehow I’d need to combine the returned status from both boilers into one to return to the thermostat.
When I go to choosing only boiler to run then emulating a boiler sounds the way to go which was why I’d hoped such a firmware already existed.
Ideal….
I placed an order (actually two) with you yesterday , I might want to add to it.
well, for fast start you can use Nest as a control unit only, i.e. get ‘desired-actual’ temperatures from it and always respond to it with some static data (get it from real boiler) and the rest of logic can be pulled from existing examples.
How is your setup working now? i mean you already have 2 boilers and one thermostat
Ahh no - my boiler (non opentherm) has failed and can’t be repaired so I am planning having two ATAG boilers installed , for redundancy. I am just trying to understand aspects of the dual control that might be problematic.
So I can’t test currently but I will follow that advice when they are installed.
I have been without heat for 6 weeks and still 4 more until install 
the only problem is that you need to write code by yourself) but the logic can be any you wish, and once you’ve figured out how to talk to nest - controlling boilers is easy, just a few commands
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It will likely be evoHome that I use - anyone using that with this DIY project ?
My whole HA system centres around MQTT so that I’m very familiar with.
I have changed the system to constant modulation now instead of on/off modulation due to high consumption. I will verify if this makes a difference in the comming days. Is anyone using zone heating here? I have valves that shut off the water to certain radiators if things get too warm in these rooms. But how do you tell the diyless if a room is too cold. For example my living room is south based, it easily gets 23 degrees there on a sunny winterday. The back of my house is north, and it can get 18 degrees there on the same sunny day if the heating is off. do you guys use a sensor with a mean value or do you use another strategy?
In my home I’ve set the “coldest” place / room as a reference and feed the temperature from there to opentherm. I use the valves on my radiators to limit the heat, just to make sure other rooms wont get to hot. OT takes care about the central heating water temperature, so the temperature is sufficient to heat up the house and the valves control the temperature individually in each room.
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Hello, I want to use the opentherm protocol for my boiler.
I got the different source codes from the diyless blog, site on which I also bought the gateway (master + slave)
Shcherban in your message you indicate that there is an option to put an other sensor than the internal sensor of the shield, but where is this option in the sketch ?
Also in the DIYLESS blog I did not find a tutorial to use both the master shield with homeassistant in mqtt and the slave shield with a wall opentherm thermostat (in the event of a homeassistant crash).
FYI, I’m very bad at programming;)