Heat pump design: The key to efficient heating

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Heat pumps are a key technology for heating and cooling buildings. They are environmentally friendly and can help to reduce energy consumption and thus reduce energy costs. But as with any technology, there is room for improvement and optimization. When planning a heat pump, particular attention should be paid to a precise design and dimensioning.

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What is a modulating heat pump?

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Modulating heat pumps operate continuously within a defined output range. At moderate outdoor temperatures, they work as needed with lower modulation and dynamically increase their output when outside temperatures fall or short-term fluctuations in demand. This distinguishes them from older models with constant speed, which could only switch between operating states “on” and “off”. Their working curve is a line, as they work continuously and the compressor continuously adjusts its speed to the respective heating and hot water requirements.

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Consequences of an oversized heat pump

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An oversized heat pump can have adverse effects. It can waste energy by clocking unnecessarily — this is equivalent to stop-and-go operation. It delivers too much heat in a short period of time, which is why it must then switch off again. A high cycle rate excessively loads the individual components of the refrigeration circuit and leads to phases of hypothermia and overheating. This inefficient mode of operation can significantly reduce energy efficiency.

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The importance of outdoor temperatures

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When designing a heat pump, the temperatures in front of your own front door play a decisive role. There are regional differences, such as the “real winters” in the Ore Mountains or the more mild winters in the Rhine Graben. It is also necessary to consider how many hours per year the particularly low temperatures are actually reached locally.

Very good statistical data is available throughout Germany to answer these questions, for example from the Federal Heat Pump Association (bwp). This data can help design a heat pump and help to maximize its efficiency.

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The role of the heating rod

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The heating element is an important element when configuring a heat pump. It is used when the temperature drops below the bivalent point (maximum output of the heat pump at the bivalent temperature of the outside air) and the maximum output of the heat pump decreases slightly as temperatures fall. As temperatures continue to fall, the efficiency of the heat pump decreases and a so-called “supply gap” occurs between the output of the heat pump and the actual heating demand of the building. This gap is closed by the electric heating element, the heating rod. However, these particularly low temperatures only occur for very few hours a year, which is why the use of the heating rod is therefore rarely required.

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Benefits of optimised design and operation

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The correct planning and dimensioning of a heat pump can help to ensure that around 97% of the annual heating work is covered by the heat pump itself. This maximizes the operating hours of the compressor in modulating mode and enables uniform and demand-based heating of the building. Operation with long running times in the partial load range is extremely efficient, as flow temperatures can be minimized. At the same time, the components of the refrigeration circuit are protected.

In addition, a smaller size is cheaper to invest than a larger one. A modulating heat pump can use self-generated photovoltaic electricity very efficiently due to its continuous but low power requirement. During the transition period, it is therefore actually possible to heat independently of energy.

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Conclusion

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The correct design and sizing of heat pumps is essential for the efficiency and benefits of this technology. Using modulating heat pumps and taking outdoor temperatures into account can help to minimize energy consumption and maximize comfort. At the same time, this can help to reduce operating costs and extend the life of the heat pump.

We would be happy to provide you with support and further information on how to make optimal use of heat pump technologies. It is our goal to fully utilize the potential of the heat pump and make your home or business more sustainable and energy efficient.

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Image credits: Colasufa, pixabay.com