We have developed and built our heat pump system with an ice/water tank and a ribbed solar/air collector as heat source, we have programmed the control system and developed software for data analysis and simulations.

Since 2012 we have supported other Do-It-Self enthusiasts in middle Europe with building similar, but highly customized, systems. We have always worked remote-only. As of 2019, we provide these services only to long-term clients.

We have documented our research and the optimization of the system on our blog(s):

Ice Storage Heat Pump System
The heat pump system developed by punktwissen uses a water tank and an unglazed solar collector as a heat source.

Measurement Data
Yearly and monthly overviews of key performance data - energies - temperatures, diagrams of daily changes, and an overview of the system's specification

How Does It Work? (The Heat Pump System, That Is) (2016-01-07)
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 throughout a typical year.

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

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

The Collector Size Paradox. (2017-11-01)
‘Collector harvest’ does not change much if we only use half the collector. Perhaps counter-intuitive but explained by the characteristics of heat exchangers connected in series: Especially if one of the heat exchangers (in the tank or collector) is already much superior to the other one, it does not help to optimize the good one further.

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

Simulations: Levels of Consciousness (2017-08-17)
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.

Simulating Peak Ice (2017-05-02)
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. Simulated maximum volume is just 0,7m3 greater than the measured volume, and the true plateau of ice (for about two weeks) is modeled correctly.

Mr. Bubble Was Confused. A Cliffhanger. (2017-04-08)
Our automated level sensor underestimated the volume of ice in the melting phase. In the coldest January since 30 years Mr. Bubble ware driven over the edge. He had to deal with a cliff … of ice.

Ice Storage Hierarchy of Needs (2017-02-22)
Mulling upon ‘Peak Ice’ in our heat pump system – and detailed simulations versus simple energy accounting. Why the maximum volume of ice obtained in a season depends sensitively on the properties of ground and the collector.

Earth, Air, Water, and Ice. (2017-02-05)
Data analysis of the heating season 2014/15 (when we turned off the solar/air collector to simulate a harsher winter). From the net energy in the tank the contribution of ground can be calculated. Data also show that the collector is delivering the more energy the colder the tank is. There are two kinds of 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.

Same Procedure as Every Autumn: New Data for the Heat Pump System (2016-10-21)
Similar results as last year, minus special research projects but plus a bit of nostalgia – when celebrating the 4th anniversary of starting up the system.

Economics of the Solar Collector (2015-10-14)
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.

Heat Pump System Data: Three Seasons 2012 – 2015 (2015-09-29)
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.

Having Survived the Hottest July Ever (Thanks Natural Cooling!) (2015-08-11)
How to use the heat pump’s heat source – the underground water / ice tank – for natural cooling in summer (plus: a brief overview of the whole system, heating versus cooling modes).

Ice Storage Challenge: High Score! (2015-04-01)
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. Toying with theories about heat transport ...

The Ice Storage Challenge (2015-03-08)
e switched off the solar collector at the beginning of February "for research purposes". This is the status report!

More Ice? Exploring Spacetime of Climate and Weather (2015-01-28)
A simplified simulation based on historical weather data: How large should this tank be so that it would hardly ever freeze completely in typical Eastern Austrian winters?

We Want Ice! (2015-01-15)
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.

Big Data, Big Plastic Worms, and How to Utilize Your Cellar (2014-09-07)
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.

Art from Plastic and Wood (2014-05-31)
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. This is a condensed cross-post of a series of posts published to our German blog.

Controlling the Four Elements. Or: Why Heat Pumps Are Cool (2013-02-26)
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.

For an overview of all heat pump / energy engineering related articles see this overview page on the blog. Even more details are available on our German blog.

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punktwissen Proyer & Stangl OG, Zagersdorf, Austria
Consulting Engineers in Applied Physics and IT Consultants