Heating check

Save cash with the heating check

A heating system that is incorrectly dimensioned or incorrectly adjusted uses more energy than necessary. This has a negative impact on your costs and on the environment. The heating check reveals any weak points in your heating system. This saves you valuable and costly energy.

What is the difference between a heating check and heating maintenance?

Heating maintenance involves evaluating the efficient functioning of the heating system and carrying out any necessary repairs. The heating check is a procedure defined in the DIN EN 15378 standard, with which the entire heating system is assessed for optimum heat generation.

During the check, the individual components of the heating system are evaluated according to a points system and opportunities for improvement are thus identified. The check consists of various measurements and assessments of the individual components of the heating system.

Who carries out the heating check?

The heating check according to the DIN standard is exclusively carried out by specialist companies. Qualified installers have to regularly take part in appropriate training courses to keep them up to date.

How a heating check is conducted

The heating check according to DIN EN 15378 consists of 13 individual steps.

Step 1 – Measurement of the exhaust gas loss

The measurement of the exhaust gas loss is based on the 1st German Immission Protection Ordinance (BImSchV). If this measurement has already been carried out by a specialist in the current heating period, it is need not be repeated. The value obtained by the specialist is then adopted.

Step 2 – Measurement of the surface losses

In this case, the heating expert scans the surface of the boiler with a temperature sensor in order to measure the surface loss or the heat loss at the heat generator.

Step 3 – Measuring the ventilation loss

Ventilation loss refers to the heat lost after the burner has been switched off.

Step 4 – Use of condensing technology

All modern gas and oil heating systems use condensing technology. Only old heating systems lack this process. They have a significantly lower degree of efficiency, which adversely impacts the point total in the heating check.


Step 5 – Size of the boiler

An overdimensioned boiler also results in a worse score because it is inefficient.


Step 6 – Control of the boiler

In this case, the points depend on the type of control. There are three options: no control at all, room-based control or control based on outside temperature.


Step 7 – Domestic hot water (DHW) heating

Another important question is: Does the heating system heat the drinking water or is there an independent DHW heating system?


Step 8 – Hydronic balancing

In this step, things like the dimensioning of the heating pump, the setting of the differential pressure regulator or the presence of thermostatic valves are checked.

This enables the specialist to see whether hydronic balancing has been carried out or not. The heating can only work optimally with this hydronic balancing.


Step 9 – Checking the heating pump

Is the heating pump correctly designed and set correctly? How much electricity does it use? These questions are not answered by measurements, but by evaluating planning documents.


Step 10 – Insulation of the pipes

Ideally, all heating pipes should be insulated. This is particularly important in unheated rooms such as the basement. Uninsulated pipes make for a worse score.


Step 11 – System temperature

The system temperature is the difference between the feed and return temperatures. If it is set incorrectly, this has a negative effect on the efficiency of the heating system.


Step 12 – Check control equipment

In this case, the heating technician checks whether the radiator thermostats in various rooms are equipped with modern, energy-saving technology. If it is an underfloor heating system, the specialist will check the room controller.

Step 13 – Renewable energy sources

Do you use renewable energies such as a heat pump to produce heat or hot water? This will improve your score.

What a heating check tells you

Points are awarded for each of the components listed above. The lower the number of points, the better the heating system. The points are awarded as follows:


  • Boiler: The first six steps of the test relate to the boiler. Together they add up to 0 to 50 points.
  • In the worst case, domestic hot water generation scores 3 points.
  • The next four steps deal with the heat and hot water distribution. Here between 0 and 55 points can be assigned.
  • The heat transfer has an impact of up to 15 points.
  • If you are not yet using renewable energy, this results in up to 15 additional points.


The maximum possible number of points for the worst system is 138. If the result of the heating check is between 0 and 25% of the total number of points, your heating system is in top shape.

In that case, you don’t have to do anything else. If the system is rated at a percentage between 25 and 75, it is time for the corresponding optimisations (i.e. from around 35 points).

A specialist company can give you specific recommendations for optimising the system based on the respective scores for the individual areas. For example, you could have the control retrofitted or install new thermostatic valves.

The closer the score of your heating system to the maximum 138 points, the sooner you should think about replacing the heater.

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