IRT-ESP is a project to build an electronic controller circuit using an Espressif ESP8266 micro controller to communicate with iRT based Boilers from the Nefit Ecomline HR Classic range and compatibles such as Buderus.
This project is a fork of the Victor-Mo iRT-ESP and Proddy EMS-ESP project. Victor is no longer actively maintaining his project, so I've decided to do my best to develop it further.
It can operate in two modes: active and passive. In passive mode it just decodes iRT messages and report the status via MQTT or the build-in web interface. In active mode it can maintain a set water temperature, but this is a work in progress. Currently the only supported hardware is a modified EMS Bus gateway from BBQKees. Without the hardware modification it will not work !
For more information about the iRT protocol have a look at Victors wiki, additional information you can find here.
In passive mode the firmware can decode the water temperature, if the boiler is running, what mode: heating or warm water, and if the pump is running. It also can show the number of burner starts, runtime of the burner, set- and current power of the burner, set- and current flowtemp, the return temperatur of the boiler, ... if the connected thermostat request the information.
In the active mode it will start the burner and sets a max water temp. The burner power will be set by a PID-regulator depended on the water temperature you set, 'boiler flowtemp 35' will set a target flow temperature of 35°C and a very low burner power. 'boiler flowtemp 90' will run the boiler at full power but not necessarily on a maximum flow temperature of 90°C because it is limited on a setting which can be changed by 'set maxflowtemp XX' (standard value is 60°C).
For my needs it is useful to target the regulation on the return-temperature, but you can change this in the user-settings.
I also added a restart delay, so the burner will not immidatly restart if the flow- (or return-) temperature falls below the selected flow-temperature, but will wait for (standard) 10 minutes and start again. In the meanwhile the burner is off, but the heat pump is running.
Please keep in mind this software is not anymore too experimental. It works on my boiler, it may not work on yours. The active mode can seriously damage your boiler, for example running it at full power for extended time. Always monitor your boiler when running in active mode !
Please keep also in mind, that in active mode, the gateway must be the only device on the bus (beside the boiler ;-) ). That means you can't use your thermostat anymore.
But if it does not work, create a log file (log j), create a ticket, and I will see what I can do.
For building the software, have a look at the EMS-ESP wiki and iRT-ESP wiki.
The default tx_mode is now set to passive IRT mode. Telnet to the device and enable logging (log j). The output should look like this (depending on your thermostat):
log j
System Logging set to Jabber mode
(00:56:43.985) irt_parseTelegram: 00 05 35: 01 01 FE 90 90 E6 E6 D0 D0 2E 2E CF 30 82 82 6B 6B B8 B8 86 86 00 FF A3 A3 07 07 D3 D3 CA CA 03 FC A4 A4 7D 7D AC AC DC DC 2A D5 8A 8A A1 A1 98 98 83 83 FE 01
(00:56:48.985) irt_parseTelegram: 00 05 35: 01 01 FE 90 90 40 40 5A 5A 61 61 CF 30 93 93 73 73 0E 0E 4D 4D FF 00 C9 C9 C3 C3 79 79 AB AB 00 FF F0 F0 01 01 CD CD ED ED 00 FF F0 F0 01 01 D8 D8 B9 B9 05 FA
(00:56:54.025) irt_parseTelegram: 00 05 35: 01 01 FE 90 90 C3 C3 79 79 F2 F2 CF 30 82 82 C3 C3 79 79 E0 E0 00 FF A3 A3 C3 C3 79 79 C1 C1 03 FC A4 A4 C3 C3 79 79 C6 C6 2A D5 8A 8A C3 C3 79 79 E8 E8 FE 01
(00:56:59.065) irt_parseTelegram: 00 05 35: 01 01 FE 90 90 C3 C3 79 79 F2 F2 CF 30 81 81 C3 C3 79 79 E3 E3 51 AE 86 86 C3 C3 79 79 E4 E4 E9 16 85 85 C3 C3 79 79 E7 E7 74 8B 83 83 C3 C3 79 79 E1 E1 A0 5F
(00:57:03.625) irt_parseTelegram: 00 05 35: 01 01 FE 90 90 C3 C3 79 79 F2 F2 CF 30 82 82 C3 C3 79 79 E0 E0 00 FF A3 A3 C3 C3 79 79 C1 C1 03 FC A4 A4 C3 C3 79 79 C6 C6 2A D5 8A 8A C3 C3 79 79 E8 E8 FE 01
In order to work in active mode the IRT-EMS-ESP should be the only device on the bus ! Telnet to the device and issue the following commands:
set tx_mode 5 (also possible to set in the web-UI of the device)
restart
The device will now restart, if the device is back. Reconnect and enable logging (log j). The output should look like this:
log j
System Logging set to Jabber mode
(00:00:14.769) irt_rawTelegram: 00 05 01: 00 - "."
(00:00:14.869) irt_rawTelegram: 00 05 01: 01 - "."
(00:00:14.990) irt_rawTelegram: 00 05 01: 02 - "."
(00:00:15.110) irt_rawTelegram: 00 05 01: 03 - "."
(00:00:15.230) irt_rawTelegram: 00 05 01: 00 - "."
(00:00:15.288) irt_tx: 01 05 1E: 90 A5 F0 28 00 00 82 A5 F0 3A 00 00 A3 A5 F0 1B 00 00 A4 A5 F0 1C 00 00 8A A5 F0 32 00 00
(00:00:15.330) irt_rawTelegram: 00 05 01: 01 - "."
(00:00:15.450) irt_rawTelegram: 00 05 01: 02 - "."
(00:00:15.570) irt_rawTelegram: 00 05 01: 03 - "."
(00:00:15.670) irt_rawTelegram: 00 05 01: 00 - "."
set(00:00:16.571) irt_rawTelegram: 00 05 35: 01 01 FE 90 90 A5 A5 F0 F0 28 28 67 98 82 82 A5 A5 F0 F0 3A 3A 00 FF A3 A3 A5 A5 F0 F0 1B 1B 03 FC A4 A4 A5 A5 F0 F0 1C 1C 20 DF 8A 8A A5 A5 F0 F0 32 32 FE 01
| 81:35 82:00 83:A0 85:74 86:E9 8A:FE 90:67 A3:03 A4:20 0H
Set the desired water temerature (set_water 30) and change the logging to only show the status line (log s):
log s
System Logging set to Solar Module only
01:35 04:00 05:04 07:00 11:FF 14:00 15:04 17:FF 73:52 78:05 | 81:35 82:00 83:A0 85:74 86:E9 8A:FE 90:67 93:00 A3:03 A4:1F A6:1E C9:05 E8:05 ED:00 0H
Starting scheduled query from EMS devices
01:35 04:00 05:04 07:00 11:FF 14:00 15:04 17:FF 73:52 78:01 | 81:35 82:00 83:A0 85:74 86:E9 8A:FE 90:67 93:00 A3:03 A4:1F A6:1E C9:05 E8:05 ED:00 0H
set_water 30
Irt set water temp, wc 1
Water temp set to 30 (1e)
01:35 04:00 05:04 07:69 11:FF 14:00 15:04 17:FF 73:52 78:07 | 81:35 82:00 83:A0 85:74 86:E9 8A:FE 90:67 93:00 A3:03 A4:1F A6:1E C9:05 E8:05 ED:00 0H
01:23 04:00 05:04 07:75 11:FF 14:00 15:04 17:FF 73:52 78:05 | 81:35 82:84 83:00 85:04 86:E9 8A:FE 90:67 93:00 A3:53 A4:24 A6:1D C9:02 E8:05 ED:00 -H
01:23 04:00 05:04 07:75 11:FF 14:00 15:04 17:FF 73:52 78:05 | 81:35 82:84 83:00 85:04 86:E9 8A:FE 90:67 93:00 A3:53 A4:24 A6:1D C9:01 E8:05 ED:00 -H
The web UI is initially reachable on 192.168.4.1, the PW is admin. Here you can see the values fetched by the gateway and do some general and user settings.
The software runs on a modified EMS Bus Wi-Fi Gateway. In short; Remove the 100 KOhm resistor (R5) to ground and replace it with a 1.5 MOhm resistor to 5 Volt. Without the modification it will not work !
The 1.5 MOhm resistor works for my setup where the Thermostat is 5 meters a way from the boiler. This value may have to be adapted for different distances.
Victor-Mo adapted BBQKees's schematic to show the change: 
BBQKees also sold an already modified interface board but this is not available anymore (11/2022). But he sells the EMS interface board V3. Here you need to remove the 100 KOhm resistor (R22) to ground and replace it with a 1.5 MOhm resistor to 5 Volt (between pin 2 and pin 8 of U2).