NIBE heating curves

Let’s start with the most important thing. My NIBE heating curve charts are, somewhat inexplicably, the main reason people visit this website. There is a good chance they are the reason you are here as well.

The documentation supplied with many NIBE heat pumps is not particularly helpful if you actually want to understand or adjust the heating curve. It tends to focus on setting a desired room temperature, often assuming that an indoor room sensor is installed. If you want to understand the relationship between outdoor temperature, curve slope, offset and supply temperature, you are mostly left to figure it out yourself or ask your installer.

My own system, like many others, has no indoor room sensor and is controlled by the outdoor temperature. There are good reasons for running a heating system this way, but that is a separate discussion. What matters here is that being able to actually see the heating curves gives you a much better starting point. You can compare different slopes and offsets, see what supply temperature a curve will produce at the design outdoor temperature (DUT), and get an idea of whether the whole curve should be raised or lowered, whether the slope is wrong, or whether part of the curve may need to be adjusted separately. That is considerably more useful than waiting for colder weather, changing the slope a little, waiting again, changing it some more, and repeating the process throughout the winter.

Heating curve charts

I have created two charts. The first covers the range normally useful for a typical house in northern Sweden. The second covers a much wider range of settings and is useful for systems that require unusually low or high supply temperatures, such as underfloor heating or houses with basements.

Download whichever one matches your system and start there.