Bazsi's Home Automation blog

This post is a continuation of my last post about KNX thermostats , which is part of my series about the troubleshooting of our heating system. In the last post I gave a "software sided" intro on our smart thermostats, but I've found the control theory behind these devices even more fascinating. But first of all, let me introduce you to our thermostats: As you can see, there are some leds, a push button and a rotary control labeled from -3 ... +3. The leds indicate the current operating mode (comfort, standby & night mode), as well as frost and heat protection. The rotary control allows the user to customize the temperature in the room: the mid-point is set with KNX parameters and the user may subtract from or add to maximum 3 degrees to that value. I mentioned in the last article that the midpoints were not set to the same value, which could explain some of the temperature differences. I also mentioned that you can set an adjustment to the temperature measu...

As described in the previous incarnations of this series ( part I: introduction , part II: heating manifolds ), the heating in our new house wasn't working very well, and I was working on finding out the root cause, as someone without too much proficiency in mechanical engineering, but with a software engineer background. This installment is about our smart thermostats connected to a KNX (aka EIB) based backbone , that control the valves (turn on/off) on our heating manifolds for per-room temperature control. I described in the previous post, I was suspicious of the thermostats, as some of our rooms were set to the same temperature, and one was warm while the other was cold. These thermostats have a couple of parameters that can be adjusted that would significantly change their behavior. The most important ones from my perspective are the temperature adjustment: to offset to be added/substracted to the measured temperature to counter potential sensor errors the base setpoi...

In the last part of this series , I've outlined the heating system in our newly acquired house, which had some issues: namely it was not warm enough. As a  software engineer I was trying to find the problem by modeling the components in the system, then by coming up with a theory that could be the root cause, then either prove or disprove it by doing measurements. Even if the theory is wrong, I learn something about how the stuff works. If I am right I get closer to solving the problem. The first theory I had was about water flow. I was kind of sure that the boiler produces enough heat, but if the hot water is not flowing through the pipes in sufficient quantities our rooms will remain cold. So I was trying to find how I can find the flow information. The answer lies  in the heating manifolds: I have one of these on all floors of the house, their role is to distribute the incoming hot water into multiple downstream pipes (under the floor heating or wall heating) and...

This story is about my journey as an IT professional into the realms of heating control systems, where I had basically zero experience. I was learning the guts of such a system at my own expense, and today I am confident in changing even major parameters of my pretty complicated setup (for a house anyway). My motivation for writing this story is 1) to document it for myself and 2) to make it useful for those who are fighting similar issues. I am an engineer, but not a mechanical engineer: I had no clue about pumps, valves and control systems. Yet, I was able to decompose and understand what I found and came up with solutions to my problem(s). So here it goes. How it all started We've recently moved into a new house with one nightmare scenario: it's not going to be warm enough. I was telling my wife that this was impossible: just look at the oversized boiler in the basement. 55kW, it's HUGE. No way, we'll have issues with temperature. But at the end she is a...