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Laxilef edited this page Nov 28, 2023 · 28 revisions

Quick Start

  1. Download the latest firmware from the releases page (or compile yourself) and flash your ESP8266 board using the ESP Flash Download Tool or other software.
  2. Connect to OpenTherm Gateway hotspot, password: otgateway123456
  3. Open configuration page in browser: 192.168.4.1
  4. Set up a connection to your wifi network
  5. Set up a connection to your MQTT server: ip, port, user, password
  6. Set up a Opentherm GPIO IN & Opentherm GPIO OUT. No change for my board. Typically used IN = 4, OUT = 5
  7. Set up a Outdoor sensor GPIO & Indoor sensor GPIO. No change for my board.
  8. if necessary, set up a the Master Member ID

After connecting to your wifi network, you can go to the setup page at the address that ESP8266 received. The OTGateway device will be automatically added to homeassistant if MQTT server ip, login and password are correct.

HomeAsssistant settings

By default, the "Equitherm" and "PID" modes are disabled. In this case, the boiler will simply maintain the temperature you set. To use "Equitherm" or "PID" modes, the controller needs to know the temperature inside and outside the house.

The temperature inside the house can be set using simple automation:
sensor.livingroom_temperature - temperature sensor inside the house.
number.opentherm_indoor_temp - an entity that stores the temperature value inside the house. The default does not need to be changed.

If your boiler does not support the installation of an outdoor temperature sensor or does not provide this value via the opentherm protocol, then you can use an external sensor or use simple automation:
weather.home - weather entity. It is important that the address of your home is entered correctly in the Home Assistant settings.
number.opentherm_outdoor_temp - an entity that stores the temperature value outside the house. The default does not need to be changed.

After these settings, you can enable the "Equitherm" and/or "PID" modes and configure them as described below.

Equitherm mode

Weather-compensated temperature control maintains a comfortable set temperature in the house. The algorithm requires temperature sensors in the house and outside.
Instead of an outdoor sensor, you can use the weather forecast and automation for HA.

Ratios

N - heating curve coefficient. The coefficient is selected individually, depending on the insulation of the room, the heated area, etc.
Range: 0.001...10, default: 0.7, step 0.001

K - сorrection for desired room temperature.
Range: 0...10, default: 3, step 0.01

T - thermostat correction.
Range: 0...10, default: 2, step 0.01

Fit coefficients

Tip. I created a table in Excel in which you can enter temperature parameters inside and outside the house and select coefficients. On the graph you can see the temperature that the boiler will set.

  1. Set the K and T coefficients to 0.
  2. The first thing you need to do is to fit the curve (N coefficient). If your home has low heat loss, then start with 0.5. Otherwise start at 0.7. When the temperature inside the house stops changing, increase or decrease the coefficient value in increments of 0.1 to select the optimal curve.
    Please note that passive heating (sun) will affect the house temperature during curve fitting. This process is not fast and will take you 1-2 days. Important. During curve fitting, the temperature must be kept stable as the outside temperature changes.
    At this stage, it is important for you to stabilize the indoor temperature at exactly 20 (+- 0.5) degrees.
    For example. You fit curve 0.67; set temperature 20; the temperature in the house is 20.1 degrees while the outside temperature is -10 degrees and -5 degrees. This is good.
  3. After fitting the curve, you must select the K coefficient. It influences the boiler temperature correction to maintain the set temperature. For example. Set temperature: 23 degrees; temperature in the house: 20 degrees. Try setting it to 2 and see how the temperature in the house changes after stabilization. Select the value so that the temperature in the house is close to the set.
  4. Now you can choose the T coefficient. Simply put, it affects the sharpness of the temperature change. If you want fast heating, then set a high value (6-10), but then the room may overheat. If you want smooth heating, set 1-5. Choose the optimal value for yourself.
  5. Check to see if it works correctly at different set temperatures over several days.

Read more about the algorithm here.

PID mode

See Wikipedia. PID example

In Google you can find instructions for tuning the PID controller.

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