Set the heating curve of the heat pump correctly: Here's how!
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Stefano Fonseca ist Ingenieur für Energie und Umwelt mit über sechs Jahren Erfahrung in der technischen Gebäudeausrüstung (TGA). Er kombiniert technisches Fachwissen mit einer Leidenschaft für verständliche Kommunikation. Seit mehr als fünf Jahren schreibt er als freiberuflicher Redakteur über erneuerbare Energien und nachhaltiges Wohnen, insbesondere über Photovoltaik und Wärmepumpen.
If you want to operate your heat pump efficiently, there is no way around a term: the heating curve. But what is behind this inconspicuous characteristic that determines comfort and costs? In this article, you will learn why setting the heating curve correctly is much more than just a fine technical adjustment — and how it can save you money.
What is the heating curve of a heat pump?
The heating curve is a characteristic that describes the relationship between the outside temperature and the required heating flow temperature. It is an important metric for the efficient operation of heat pumps.
Why is the heating curve so important?
The heating curve is important in a heat pump because it controls the relationship between outside temperature and flow temperature. A correctly set heating curve ensures that the heat pump only delivers as much heat as is actually required. This improves efficiency, reduces heating costs and increases living comfort. If the curve is set too steep or too high, the heat pump works unnecessarily intensively — with higher electricity costs and possible wear as a result.
How does the heating curve work?
The heating curve works by providing a fixed relationship between the outside temperature and the flow temperature. If the outside temperature drops, the flow temperature rises — and vice versa. In this way, only as much heat is automatically provided as the building requires.
Two parameters determine the heating curve: the steepness and the parallel shift.
- The steepness regulates how strongly the flow temperature reacts to falling outside temperatures.
- The parallel shift Raises or lowers the entire curve without changing the slope.
What does such a heating curve look like?
A heating curve is an ascending line in a diagram that shows the relationship between outdoor temperature (x-axis) and flow temperature (y-axis). The curve starts with low flow values at mild temperatures and rises evenly as outside temperatures fall. The exact slope and location of the line depend on the type of building, insulation and heating system.
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Which values are ideal?
The heating curve of a heat pump usually has a slope of between 0.2 and 1.5. The ideal values depend on the type of building and the insulation standard. In well-insulated new buildings, a flat curve is usually sufficient, while unrenovated old buildings require a steeper setting so that they provide sufficient heating output.
Who adjusts the heating curve — specialist company or yourself?
The heating curve of your heat pump is usually set by a specialist company. The installer depends on the heat load, the insulation and the existing heating surfaces. In this way, it ensures that your heat pump works efficiently and comfortably.
You can also adjust the heating curve yourself later. Pay attention to small changes and observe the result over several days. If it gets too hot or too cold, adjust the curve again. If you are unsure, we recommend that you consult a specialist company.
How do you adjust the heating curve for a heat pump?
You adjust the heating curve of a heat pump by adapting the slope and parallel shift to your living situation. Proceed systematically:
- Check baseline values: Note the current slope and shift settings. These serve as a reference for subsequent changes.
- Check room temperature: Check that all rooms are pleasantly warm in current weather conditions. When doing so, watch out for cold corners or overheating.
- Adjust the slope: Increase the steepness when it's too cold when outside temperatures are low. Reduce the slope if it gets too warm or if there are high flow temperatures.
- Change parallel shift: Move the entire curve upwards when it's too cold in general — even in mild weather. Lower it if there is too much heating.
- Observe results: Wait a few days and check how room temperatures develop. Repeat the process as needed until the system is running optimally.
How do you recognize the right attitude?
The correct setting of the heating curve is indicated by the fact that all rooms are evenly warm and that the flow temperature remains as low as possible. It should be neither too cold nor too warm, even with changing outdoor temperatures. In addition, the heat pump works efficiently, i.e. without frequent cycles and with a stable annual performance factor. If comfort and power consumption are right, the heating curve is optimally adjusted.
What are the consequences of an incorrectly adjusted heating curve?
An incorrectly adjusted heating curve leads to higher energy consumption, rising heating costs and reduced living comfort. If the curve is too steep or too high, the heat pump works inefficiently and creates unnecessarily high flow temperatures. This can worsen the annual performance factor and shorten the life of the system. A curve that is too flat, on the other hand, results in hypothermic rooms, especially when outside temperatures are low.
Does the heating curve have to be adjusted regularly?
The heating curve does not have to be adjusted regularly, but should be checked if the building or heating behavior changes. After a renovation, a radiator replacement or a change in living habits, a new setting can be useful. Fine adjustment is also worthwhile if rooms are permanently too cold or too warm. As a rule, a one-time adjustment of the heating curve is sufficient and repair only when necessary.
Optimizing the heating curve — practical tips
To ensure that your heat pump runs efficiently and you save heating costs, you should specifically optimize the heating curve. Improve comfort and efficiency with these tips:
- Adjust the slope when it's cold: If individual rooms freeze at low outside temperatures, slightly increase the steepness of the curve.
- Correct the parallel shift in mild weather: If it is too warm even at outside temperatures above 10 °C, lower the curve slightly.
- Avoid making too frequent changes: Watch each change for at least three days before intervening again.
- Only use the night reduction in a targeted manner: It is of little use in well-insulated houses; in older buildings, it can reduce heating costs.
- Check the room temperature regularly: Use simple thermometers in different rooms to check.
- Keep a log: Note down any changes and outdoor temperatures so that you can better understand the adjustments.
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