Evolution of the LWZ Monitoring: From Python to ESPHome

May 29, 2026

It’s been over a decade since I first poked around the serial interface of my Stiebel Eltron LWZ 403 SOL. What started as a “cable investigation” with a technician’s notebook has grown into a long-running community project. Today, I am happy to announce a major update to the project’s documentation and architecture!

I have moved away from the dedicated Linux server and Python daemon in favor of a modern ESPHome and Home Assistant integration. This transition makes the setup much leaner, more robust, and natively integrated into a modern smart home ecosystem.

Key highlights of the update:

• New ESPHome Integration: I’ve replaced the long serial cables with a small ESP8266 (NodeMCU) Wi-Fi bridge installed directly inside the heat pump.
• Custom C++ Protocol Handler: A new DLE protocol implementation that handles modern firmware quirks, including a fix for the elusive “0x18 ghost byte” found in versions like v4.39.
• Modern Visualization: Complete Home Assistant dashboard configuration using the ApexCharts card to replicate (and improve upon) the classic RRDTool look.
• Full Technical Deep-Dive: I’ve added detailed data block mappings and offset tables to the main page for those who want to build their own implementation.

You can find the updated guide, technical tables, and the new source code for download on the main project page:

Read the updated LWZ Monitoring Guide

A big thank you to the community for the feedback over the years. I hope this new direction helps you keep your heating systems running efficiently!

Microsoft Remote Connectivity Analyzer

May 23, 2013

By pure luck I found the Microsoft Remote Connectivity Analyzer as I’m not into the Microsoft world. Anyway this web site lets you test easily if the Groupware server you’re using is configured correctly. For example if you’ve problems connecting/syncing with your mobile or tablet to a server via ActiveSync. This protocol is not just used by Exchange but also by some OpenSource Groupware applications. Anyway its a nice link to know.

Clicky Web Analytics the alternative to Google Analytics

December 14, 2008

I’m using Google Analytics for some time now, it basically works, but it has some short comings like that the reports do only get updated every 24h, or that it is not able to track bound links without extra work on my side. But the most import part is that I don’t want that google knows everything. So I started to look for a valid alternative. I tried some local installable open source tools but decided to go with an other SaaS. If you’re using NoScript for your Firefox you might know it already I started using Click Web Analytics. Take a look at this screenshot, it looks like most web 2.0 sites, simple, clean design with a white background.

Whats nice is that you can do a real time campaign and goal tracking and that you can track every visitor who comes to your web site and if they accept cookies all their history. This will show you which power cookies gives website providers. You should really think to disable them or remove them on every start of your browser. But as long the most users have activated it I will also take a look at it and have a nice show case for people I talk over this.

Hidden Firefox feature and the plugin Pencil

September 3, 2008

I found something interesting, which I guess some already know, but still I though its a nice feature. Copy following into your Firefox browser address bar and hit enter.

javascript:document.designMode='on'; void 0


You can now change a homepage by deleting stuff or replacing some text to test something or making a faked screenshot. I think this can be really handy sometimes and it is build in. Something more sophisticated is following Firefox 3.x plugin, called Pencil (You can also download it here). Pencil is a Firefox add-on to do GUI prototyping and simple sketching, take a look at this blog post which shows what Pencil can do. As a teaser I put a screenshot at the end to this post 😉