We are an Austrian engineering consultancy: punktwissen – two physicists tinkering with control systems, heat pumps, and computer networks.

This page is a compilation of Science Officer elkement’s English blog posts tagged with ‚punktwissen‘.

[Page last edited: 2019-04-23]


Ribbed pipe collector – harvesting energy from air in winter.

[2019-01-18] Modbus Server on Raspberry Pi as Babelfish for UVR16x2. A nice-to-have extension to the existing control infrastructure. As the CMI has a Modbus interface it can log data from a Modbus running on Raspberry Pi, and this Modbus server can forward data from other loggers as a ‚protocol translator‘ and provide values derived from calculations.

[2018-12-15] Unintended 2nd Order SQL Injection. I have accepted a benign version of 2nd order SQL injection as a fact of life. But then interesting things happened when a parcel was (not) delivered.

[2018-11-18] A Color Box. Lost in Translation. The control system was turned upset down again and the Data Kraken was looking at its entangled tentacles, utterly confused.

[2018-10-14] Cyber Something. Is it called Cyber Security or IT Security? Or should we use ‘Infosec’? elkement asked Google Trends – and got some surprising results!

[2018-08-05] Hacking. Sort of an Away Note – elkement gone hacking: „I discovered the pentesting platform hackthebox and spend all my online time there! It’s all new, yet familiar as I feel I have always reverse engineered anything in some sense.“

[2018-07-10] Sources of Heat, Life, and Everything. Same procedure as every summer: Science and tech blogging comes to a halt – look at (engineering-themed) avant-garde art instead.

[2018-06-25] Cloudy Troubleshooting (2) Write-up of a hacking challenge 😉 When some network infrastructure loses packets, but seemingly only for one site / cloud app … so that it takes you a while to realize that it’s not an issue with this cloud app.

[2018-05-28] Where Are the Files? [Winsol – UVR16x2] A little bit of reverse engineering to find out where log files (retrieved from the data logger CMI) may be stored. The question was more interesting than expected – I learned something about Windows security!

[2018-05-13] Cloudy Troubleshooting. Tales from the field – presented as a drama featuring Cloud, Cliend, Telco and elkement – going down the rabbit hole of debugging, network sniffing, and mind-numbing tests.

[2018-04-24] Logging Fun with UVR16x2: Photovoltaic Generator – Modbus – CAN Bus. Playing with Modbus inputs on the Control and Monitoring Interface of the UVR16x2 controller (and corresponding settings at the Fronius Symo inverter) – step-by-step description.

[2018-04-09] Can the Efficiency Be Greater Than One? This is one of the perennial top search terms for this blog. Anticlimactic answer: Yes, because input and output are determined also by economics, not only by physics.

[2018-03-03] Consequences of the Second Law of Thermodynamics. Theory – Carnot’s efficiency again. Most textbooks introduce Carnot’s cycle by calculating energies for an ideal gas – but the efficiency would not change if the substance was not ‘ideal’ in the sense that the equation of state – p(V,T) – were different.

[2018-01-19] The Heat Source Paradox – a simple relation between a heat pump system’s key data; yet used in a misleading way in adverts: The worse performance is, the smaller the heat source can be built.

[2018-01-12] Things You Find in Your Hydraulic Schematic. I am starting the New Year of Engineering Blogging at a lighter pace – don’t expect too much content this time!

[2017-12-13] Cooling Potential. I had an interesting discussion about the cooling potential of our heat pump system – in a climate warmer than ours. So I started to think about improving cooling power, by adding active cooling functionality.

[2017-12-05] Reverse Engineering Fun. Recently I read a lot about reverse engineering – in relation to malware research. I for one simply wanted to get ancient and hardly documented engineering software to work. Write-up of an analysis I found very interesting!

[2017-11-28] Simulating Life-Forms (2): Cooling Energy. Thoughts of the ’simulation department‘ triggered by a detailed research report by the Australian government. It confirms my reluctance to ‚predict‘ cooling energy as usage of air conditioning depends strongly on life-style choices.

[2017-11-01] The Collector Size Paradox. Results and data for 5 heating seasons. Emphasis on data/tests and ‘theory’/simulations for the impact of changing the size of the solar/air collector. For our system’s parameters, using only half of the solar/air collector does not change collector energy harvest drastically.

[2017-10-21] The Orphaned Internet Domain Risk. If you abandon a domain, malvertizers may re-use it – using even your former content available on public archives … taking advantage of your former reputation. Think twice before ‘decluttering’ your digital possessions.

[2017-10-12] Data for the Heat Pump System: Heating Season 2016-2017. The usual number crunching – performance, energies, temperatures, ice – plus a summary of the system’s configuration and ‘cultural’ context. Also presenting data on passive cooling.

[2017-09-17] Tinkering, Science, and (Not) Sharing It. That moment when you realize that your tinkering with PVC piping is actually science.

[2017-08-17] Simulations: Levels of Consciousness. Getting philosophical – what is a simulation (of our heat pump system), and what are the challenges? For modern buildings, simulating ‘user behaviour’ can be as critical as simulating ‘physics’ and control logic.

[2017-07-28] Bing Says We Are Weird. I Prove It. Using Search Term Poetry. Bing (Places, Business) has done so repeatedly. What else should elkement do than creating poetry from search terms that Bing users submitted to find our websites?

[2017-07-14] Heat Transport: What I Wrote So Far. A list of all of elkement’s blog posts focussing on heat transport, plus short summaries: Heat transfer and energy storage in our heat pump system, in ground, in ice. Analytical solutions versus numerical simulations versus maverick’s heuristics.

[2017-06-17] Spheres in a Space with Trillions of Dimensions. From the theory department – just ‚old-school textbook stuff‘, nostalgically looking back on first encounters with statistical mechanics and thermodynamics. Admittedly, we don’t need this on a daily basis to size heat pump systems or the like – but sometimes obscure know-how and mathematical techniques come in handy in places where you don’t expect it

[2017-05-02] Simulating Peak Ice. Continued from last post – comparing measurements of the level in the tank with simulations of the evolution of the volume of ice. Simulations comprise a model of the control logic, the varying performance factor of the heat pump, heat transport in ground, and energy balances for the hot and cold tanks, and the heat exchangers connected in series.

[2017-04-08] Mr. Bubble Was Confused. A Cliffhanger. Tales of a level sensor: In the coldest January since 30 years Mr. Bubble ware driven over the edge. He had to deal with a cliff … of ice.

[2017-03-18] Where to Find What? A list of lists – our web resources related to the heat pump system: Data, brief explanation, FAQ, this list of postings here.

[2017-02-22] Ice Storage Hierarchy of Needs. Why the maximum volume of ice obtained in a season depends sensitively on the properties of ground and the collector.

[2017-02-05] Earth, Air, Water, and Ice. Data Kraken in action: Analyzing data for the heating season 2014/15, in terms of two different energy balances: 1) The net energy ‘in the tank’ (allowing for calculating the contribution of ground) and 2) the three heat exchangers that are connected in series in the brine circuit.

[2017-01-20] Frozen Herbs and Latent Energy Storage. From root cellar to heat source … using pond liner. Sort of step-by-step instructions, using an every day analogon.

[2017-01-07] On Photovoltaic Generators and Scattering Cross Sections. A physicist’s musings about the unit used to characterize solar panels’ peak power: kWp.

[2016-12-22] My Data Kraken – a Shapeshifter. Answer to the question: How do you analyze and consolidate your logging data? What is the biggest challenge? It’s the ongoing change of the ‘database schema’: New sensors, shuffled columns in log files, new calculated values…

[2016-11-20] Give the ‘Thing’ a Subnet of Its Own! A brief report ‘from the workbench’: How recent Internet of Thing hacks reminded me of the often overlooked ‘routing feature’ in Windows… which was helpful in quickly giving control units’ data loggers access to the internet.

[2016-11-03] And Now for Something Completely Different: Rotation Heat Pump! An invention – an answer to: Can a compression heat pump be built in a completely different way?

[2016-09-18] Re-Visiting Carnot’s Theorem. From the theory department: Why can’t there be any heat pump / heat engine better than Carnot’s reversible machine? A closer look at the proof by contradiction.

[2016-08-24] Hacking My Heat Pump – Part 2: Logging Energy Values: Querying the heat pump’s CAN bus for temperature and energy values, plus: network traces and details of CAN frames sent and received by open source tool can_scan.

[2016-08-03] Hacking My Heat Pump – Part 1: CAN Bus Testing with UVR1611. Extending logging infrastructure – automating reading off our heat pump’s internal energy meter by using Raspberry Pi as monitoring device. Before connecting to the heat pump hardware and software is set up and tested with a CAN bus we are familiar with.

[2016-06-22] First Year of Rooftop Solar Power and Heat Pump: Re-Visiting Economics. Monthly statistics: Energy ‘generated’ by the PV panels, fed into the grid or supplied from grid, consumption in the house and by the heat pump in particular. 30% of total energy consumption was provided directly by the PV generator (no battery).

[2016-06-01] Photovoltaic Generator and Heat Pump: Daily Power Generation and Consumption. Comparing detailed time curves – illustrating why it is hard to raise self-consumption and self-sufficiency above statistical averages for homes without heat pumps: PV output, input energy for the heat pump’s compressor, and the home’s total smart meter balance.

[2016-05-19] Everything as a Service. Trying to predict the not-to-distant future of heating for consumers – following the ‘as a service’ philosophy introduced to software products long ago: Heating will be turned into monthly subscriptions bundled with internet access and bank accounts, and home owners will host aesthetically pleasing black-boxes operated by ‘platforms’.

[2016-04-17] Alien Energy. An update to the previous two articles in this category. Our PV generator and power metering infrastructure is now operational for nearly a year, and I am analyzing the most peculiar day. In February, the peak power was close to the generator’s rated power for half an hour.

[2016-03-01] Rowboats, Laser Pulses, and Heat Energy (Boring Title: Dimensional Analysis). Re-visiting heat transport and heat diffusion length, this time only analyzing dimensional relationships. I introduce the concept of dimensional analysis by answering the question: How does the speed of a rowing boat depend in the number of rowers?

[2016-02-08] No, You Cannot ‘Power Your Home’ by One Hour of Cycling Daily. You need to get a feeling for numbers ‘in renewable energy’ – and it more than baffles me when authors of click-bait articles don’t bother to the most basic cross-checks. It seems we lost the feel for ‘what can power what’ when engines replaces horses and humans.

[2016-01-22] Temperature Waves and Geothermal Energy. For our numerical simulations of the heat pump system (estimating the maximum volume of ice, for example) we need 1) to make an assumption for the thermal diffusivity of ground, to calculate heat transport between the ice storage and ground, and 2) find a simplified way of accounting for the solar energy deposited near the tank. For both purposes, it is interesting to have a look at the evolving of temperature in undisturbed ground, governed by the Heat Equation. This is a post in my capacity as the ‘Theory Department’.

[2016-01-07] How Does It Work? (The Heat Pump System, That Is) The reply to numerous questions like: Can you explain – using images, with an animation – how the combination of ice/water tank and solar collector works? Here is a slide-show of operating statuses throughput a typical year.

[2015-12-07] Half a Year of Solar Power and Smart Metering. Combining data harvested by three different loggers: 1) UVR1611: Ambient temperature, heat pump compressor’s energy, 2) Fronius Symo Datamanager: PV output energy, 3) Smart Meter B-Control EM-210: Energy consumed and fed into the grid.

[2015-11-25] Peter von Rittinger’s Steam Pump (AKA: The First Heat Pump). An account of the 19th century invention, based on the original German research reports.

[2015-11-13] The Impact of Ambient Temperature on the Output Power of Solar Panels. Verified by analyzing our monitoring data – combining logging from our heat pump’s control unit (UVR1611) and the PV inverter’s logging.

[2015-10-14] Economics of the Solar Collector. My reply to an interesting question on measurement data for last season: Why invest in a solar collector if the performance factor decreases just a bit if you turn it off? Performance would not have been that high after turning the collector off hadn’t we used the collector for months before.

[2015-09-29] Heat Pump System Data: Three Seasons 2012 – 2015. Brief summary of last season’s performance, plus back-of-the-envelope estimate of economics: Heat pump versus natural gas, based on costs of energy in Austria.

[2015-08-11] Having Survived the Hottest July Ever (Thanks Natural Cooling!)

[2015-08-01] Travelling Like Spam Poetry. Finally explaining how we really make life-altering decisions, like starting this company. In 2005 The Chief Engineer and elkement visited more than 100 villages whose names started with letter Z.

[2015-07-15] Solar Energy, Batteries, and Autonomy. Third post on our PV generator – with data for the first two months, and my personal assessment of using battery storage.

[2015-06-17] Solar Power: Some Data for the First Month. Figures and numbers from our PV generator’s logging: Efficiency of solar panels decreasing with temperature, intermittent short and very high power spikes, and daily energy balances (consumption / generation / grid).

[2015-06-01] An Efficiency Greater Than 1? The Coefficient of Performance of a heat pump is much greater than 1 which is due to the definition, omitting input ‘ambient energy’. The rather high factor gives proof of the fact that heat pumps operate well above absolute zero.

[2015-05-18] Two Weeks After Lift-Off. An update on our photovoltaic energy generator: safety features, startup, and data for the first two weeks. Currently about 55% of the energy consumed by appliances and the heat pump come directly from the solar panels.

[2015-05-07] Watching TV Is Dangerous. Data logger BL-NET is silenced by an IP-TV in the same LAN; solution: Put the logger in its private subnet.

[2015-04-21] How to Evaluate a Heat Pump’s Performance? Definitions of performance indicators and how to determine them – comparing alternative methods, based on sensors available (COP from temperatures versus Performance Factor from energy readings).

[2015-04-01] Ice Storage Challenge: High Score! At the beginning of February we had turned off the solar collector to mimic a harsher winter. The ice cube, generated by our heat pump since then, stopped growing at about 15m3. About 10m3 of water remained unfrozen. After a few days in this steady state we turned on the collector again and resumed standard operations.

[2015-03-23] We Have Come a Long Way: Rooftop Solar Power Now! We had rebuilt half of our house but not installed solar panels – until recently. Here are some photos and a back-of-the-envelope assessment of economics of PV (in Austria); so now we harvest both energy inputs for the heat pump: Ambient and electrical energy.

[2015-03-18] Data Logging with UVR1611 – FAQ. What I would have wanted to read when I once made myself familiar with the freely programmable controller. I am responding to several, similar questions in this post.

[2015-03-08] The Ice Storage Challenge. We switched off the solar collector at the beginning of February “for research purposes”. This is the status report!

[2015-02-27] “An Unprecedented Test for Europe’s Electricity System”. Solar power and the impact of a solar eclipse. Soon we will contribute – our PV generator has already been ordered.

[2015-02-14] A Sublime Transition. Phase transitions between water, vapor, and ice: Last winter’s viral trend of freezing boiling water in mid-air, and discovering that scientists discuss such effects to this day.

[2015-01-28] More Ice? Exploring Spacetime of Climate and Weather. A simplified simulation based on historical weather data: How big should the ice / water tank (used as a heat source) be?

[2015-01-22] Personal Risk Assessment. The previous post on our ice-storage powered heat pump triggered an interesting discussion about the risk of a power outage. Is it more risky to pick a heat pump – compared to other systems?

[2015-01-15] We Want Ice! Current measurement data showing the formation of ice in the ‚ice storage‘ water tank. Winter is mild here, so there was only 1m3 ice so far. But we might partially deactivate the collector to test the generation of a bigger ice cube.

[2014-12-14] Cistern-Based Heat Pump – Research Done in 1993 in Iowa. Elkement stumbled upon a research report that described a heat pump similar to ours – except for the fact that the authors considered the collector not essential, based on a crude steady-state estimate of the heat flow from ground to the tank. Pionieering work though as they built the solution incl. data acquisition from scratch.

[2014-11-29] “Being Creative with What Is Available” – this refers to playful tinkering in general, and to building solar collectors and ice storage systems for very special buildings.

[2014-11-15] Google and Heating Systems (2). Again the Internet of Things! One of my favorite things is the data logger for our heat pump system and gateway between CAN bus and ethernet – C.M.I. by Technische Alternative. Plus some consolidated research on how Things phone home, and my rants on not using passwords with internet-facing systems.

[2014-11-08] A 1970s Pioneer in Self-Sufficient Living. This is about heating power from compost and not even tagged with ‚Heat Pump‘ – but nonetheless I can relate to Jean Pain’s ideas. I know what it means to be driven by the quest for self-consistency in your life-style choices, your hobbies, and in the way you work.

[2014-10-04] Pumped Heat from the Tunnel – my summary of a press release that announced a EU ‚Smart City‘ project. I focus on using water from an infamous tunnel as heat source of a heat pump.

[2014-09-28] Biology / Chemistry Challenge or: Should We Really Blame the Dead Frog? Normally, the water in the tank does not need to be drained or replaced. Except: You started pesky anaerobic reactions as you feed the bacteria in the water too much brine.

[2014-09-07] Big Data, Big Plastic Worms, and How to Utilize Your Cellar: An update on the status of our heat pump system – the solar collector has been overhauled – and looking back with nostalgic feelings! What you never wanted to know about small houses and their earth cellars in Eastern Austria.

[2014-05-31] Art from Plastic and Wood: Some pictures of a solar collector built for a client. The water tank is located beneath the garage, and the solar collector installed on top of it.

[2014-04-13] Measurement Data for Our Heat Pump System – Finally Translated Documentation: This document also includes a more detailed description of the system and some configuration parameters.

[2014-02-20] Lost in Translation – an Overdue Update: Short overview and bold announcement of more technical documents to be translated to English.

[2013-09-04] Greatest Innovation Ever: Thoughts on the power grid – tangentially related to heat pumps that are often considered sort of buffer that will help too stabilize the smart grid (via demand side management).

[2013-08-14] Welcome to the Real World! Actually an away note from my social media break – but also showing off our tomato plants, attached to the solar collector used as an espalier. I’ve included brief information on the operations of the collector in winter versus summer (cooling mode)-

[2013-02-26] Controlling the Four Elements. Or: Why Heat Pumps Are Cool: Hydraulic design and short overview of our heat pump system that uses a water tank (‚ice storage‘) ‚powered by‘ an unglazed solar collector as its heat source.

[2013-01-22] Trading in IT Security for Heat Pumps? Seriously? More of a personal essay on my career transitions, including a small section on the system. Adding a note in 2014: I probably would not call it Trading in… today, but rather combining with...

[2012-12-10] The First Heat Pump Ever Was Built in Austria: History on engineering – set in my home country.

[2012-05-10] Why Do Heat Pumps Pump Energy so Easily? Brief (yes, really) explanation how a heat pumps works.