Tag: Engineering

Re-Visiting Carnot’s Theorem

The proof by contradiction used in physics textbooks is one of those arguments that appear surprising, then self-evident, then deceptive in its simplicity. You – or maybe only: I – cannot resist turning it over and over in your head again, viewing it from different angles. tl;dr: I just wanted to introduce the time-honored tradition…
Hacking My Heat Pump – Part 2: Logging Energy Values

In the last post, I showed how to use Raspberry Pi as CAN bus logger – using a test bus connected to control unit UVR1611. Now I have connected it to my heat pump’s bus. Credits for software and instructions: Special thanks to SK Pang Electronics who provided me with CAN boards for Raspberry Pi…
Hacking My Heat Pump – Part 1: CAN Bus Testing with UVR1611

In the old times, measuring data manually sometimes meant braving the elements: Now, nearly all measurements are automated: In order to calculate the seasonal performance factor of the heat pump system we have still used the ‘official’ energy reading provided by the heat pump’s display. Can’t this be automated, too? Our Stiebel-Eltron WPF7 basic is…
First Year of Rooftop Solar Power and Heat Pump: Re-Visiting Economics

After I presented details for selected days, I am going to review overall performance in the first year. From June 2015 to May 2016 … Disclaimer: I am from Austria –> decimal commas and dot thousands separator :-) The photovoltaic generator … Monthly energy balances show the striking difference between summer and winter: In summer…
Everything as a Service

Three years ago I found a research paper that proposed a combination of distributed computing and heating as a service: A cloud provider company like Google or Amazon would install computers in users’ homes – as black-boxes providing heat to the users and computing power to their cloud. In the meantime I have encountered announcements…
Alien Energy

I am sure it protects us not only from lightning but also from alien attacks and EMP guns … So I wrote about our lightning protection, installed together with our photovoltaic generator. Now our PV generator is operational for 11 months and we have encountered one alien attack, albeit by beneficial aliens. The Sunny Baseline…
How Does It Work? (The Heat Pump System, That Is)

Over the holidays I stayed away from social media, read quantum physics textbooks instead, and The Chief Engineer and I mulled over the fundamental questions of life, the universe and everything. Such as: How to explain our heat pump system? An astute reader suggested to create an ‘animation’ of the gradual evolution of the system’s…
Peter von Rittinger’s Steam Pump (AKA: The First Heat Pump)

Peter von Rittinger’s biography reads like a Victorian novel, and his invention was a text-book example of innovation triggered by scarcity. Born 1811, he was poor and became an orphan early. Yet he was able to study mathematics and physics as his secondary education had been financed by the Piarist Order. He also studied law…
The Impact of Ambient Temperature on the Output Power of Solar Panels

I have noticed the impact of traversing clouds on solar power output: Immediately after a cloud has passed, power surges to a record value. This can be attributed to the focusing effect of the surrounding clouds and/or cooling of the panels. Comparing data for cloudless days in May and June, I noticed a degradation of…
Economics of the Solar Air Collector

In the previous post I gave an overview of our recently compiled data for the heat pump system. The figure below, showing the seasonal performance factor and daily energy balances, gave rise to an interesting question: In February the solar collector was off for research purposes, and the performance factor was just a bit lower…
Heat Pump System Data: Three Seasons 2012 – 2015

We have updated the documentation of monthly and seasonal measurement data – now including also the full season September 2014 to August 2015. The overall Seasonal Performance Factor was 4,4 – despite the slightly lower numbers in February and March, when was the solar collector was off during the Ice Storage Challenge. Edit: I have…
Having Survived the Hottest July Ever (Thanks, Natural Cooling!)

July 2015 was the hottest July ever since meteorological data had been recorded in Austria (since 248 years). We had more than 38°C ambient air temperature at some days; so finally a chance to stress-test our heat pump system’s cooling option. Heating versus cooling mode In space heating ‘winter’ mode, the heat pump extracts heat…
Solar Energy, Batteries, and Autonomy

This is the third post in my series on our photovoltaic generator. It had been a part of previous post with the data for the first month, but I cut and saved it as the other post was so long already. I am now also able to present data for two months of operations: Below…
Solar Power: Some Data for the First Month.

On May 4, 2015, we started up our photovoltaic generator. Here are some numbers and plots for the first month – and what I plan to do next. Our generator has a rated power of 4,77 kWp (kilowatt peak), one module has 265 Wp. The generator would deliver 4,77 kW of electrical power under so-called…
Two Weeks After Lift-Off

After a little delay our photovoltaic generator went online – we had been waiting for the delivery of this sophisticated addition to our office decoration: People on G+ had very cool suggestions, such as a rotating alien-fighting device throwing darts. Closest to the truth were: fuse box and fire alarm. The box containing two knobs…
Watching TV Is Dangerous

I am not talking about humans. But TV-sets might threaten other devices in the smart home; this was a recent puzzle submitted by a blog reader. Two unrelated devices / services met on the user’s local computer network: This user had one of the solutions in place that I mentioned in my previous post on…
How to Evaluate a Heat Pump’s Performance?

The straight-forward way is to read off two energy values at the end of a period – day, month, or season: The Seasonal Performance Factor (SPF) is the ratio of these – the factor the input electrical energy is ‘multiplied with’ to yield heating energy. The difference between these two energies is supplied by the…
Ice Storage Challenge: High Score!

Released from ice are brook and river By the quickening glance of the gracious Spring; The colors of hope to the valley cling, And weak old Winter himself must shiver, Withdrawn to the mountains, a crownless king. These are the first lines of the English version of a famous German poem on spring, from the…