Heating with fuel shortage

What levers can the housing industry and end consumer use?

CANZLER shows suitable levers for housing companies and their tenants. The focus is on the simplest possible ways of dealing with energy consumption - from heat generation to the heat user.

By Andreas Stehling, Managing Director at CANZLER GmbH and Head of the Technical Equipment Division for the sanitary, media and fire extinguishing technology, heating, ventilation and refrigeration technology trades.

Current situation

Over the past three decades, most existing heating installations have been converted to gas heating, which was previously inexpensive. But now the popular fuel gas has become much scarcer and no one can reliably foresee what will happen to gas as a fuel on the world markets. In view of the energy crisis, impending supply bottlenecks and rising prices, politicians and various experts are advising people to cut back. This presents companies in the housing industry with the major challenge of how to save energy.

Against this backdrop, CANZLER looks at heating and the water heating system attached to it, and points out suitable adjusting screws for housing companies and their tenants. The focus is on the simplest possible ways of dealing with energy consumption - from heat generation to the heat user, the people.


Optimize settings

Before the heating period begins, usually from October to April, it is advisable to check the systems and readjust them if necessary.

  • Heat generators in the sense of residential construction form the district heating, the central boiler or the gas floor heating. As it stands today, such generators have an outdoor sensor, a flow sensor and a timer. Depending on the outdoor temperature, the flow temperature is set with a so-called heating curve. Again in relation to the time specification, this heating curve is run. The stored curve means that the colder it is outside, the warmer the flow.

    To check the heating curve setting, responsible janitors or FM service providers should perform a simple test. To do this, turn up the heat in a cold room with the radiator cold, i.e., the thermostatic valve. If you feel a hot water flow that you don't want to touch because of the heat, and later, e.g. after half an hour, you feel that only the top ten or 20 cm of the radiator are warm, but the room is sufficiently heated, then it can be assumed that the heating curve is set significantly too high.
  • The following applies to the timer: the times should be set according to the demand. Radiators react quickly, so set the clock so that the heating starts half an hour before use. Since underfloor heating reacts rather sluggishly, set the clock to operate one hour before use. This rule applies analogously to the reverse case in order to use the residual heat! In addition, it remains to consider whether it makes sense to switch off the heating by timer for two to three hours, e.g. over midday.

    Usually the clock switches a so-called day and night operation. Night operation is then lowered, e.g., 3 °C less than during the day is often preset as the standard room temperature. Modern, well-insulated houses manage without nighttime heating operation. How the shutdown works in individual cases can be found in the instructions.


Use internal loads

Circulation areas such as hallways and stairwells do not need their own heating, even if there are waiting areas for people in these areas.

  • Usually, the building has enough internal loads that adequate temperatures will occur. Freezing temperatures will not occur. Ideally, the operator locks the return screw connection of the heating surfaces, because a turned-down thermostatic valve fails to work, since it can be adjusted by anyone.


Pay attention to consumption

The usage behavior of end users has a major impact on energy consumption. This is why they are particularly called upon to reduce consumption for heating and hot water.

  • If you heat the room to 22 °C when the thermostatic valve is set to e.g. 2.8, try setting the valve to e.g. 2.4 to heat the room 2 °C lower. Thermostatic valves are sensitive to small readjustments. However, an adjustment from e.g. 4.0 to 1.5 (i.e. from open to frost protection) misses the desired target and does not ensure uniform heating.
  • If you do not use a room for a longer period of time, do not set the valve to frost protection, but e.g. to 1.5 or 2.0. A room temperature of 16-18 °C should be reached. Below 16 °C the cooling is too big, then also the walls cool down so much that they radiate the cold again. With 18 °C in the room, a rather fast reheating can be assumed for sporadic use.
  • There are not so many options when it comes to heating water. The water in the storage tank must be kept at 58 or 60 °C, otherwise there is a risk of contamination. In addition, the generally accepted rules of technology, in particular VDI 6023, prescribe keeping the temperatures high. For hygienic reasons, switching off the circulation pump should not be considered. Should the users manage without constant circulation by self-testing, it would have to be consistently disconnected from the system. This is because no standing water should remain in the system at the end. The energy for heating drinking water can only be reduced by lower consumption by the users and by using water-saving fittings.


Excursus on the subject of airing and Corona

Regular ventilation was the motto in the last two years because of the Corona pandemic. In practice, it often turned out that in the corridors of administrative buildings, with the windows constantly set to tilt, the radiators fought against the cold and drafts. We can no longer afford this in view of rising prices and the impending gas shortage.



The key message involves cautious trial and "play" with the thermostatic valve and setting options. In residential areas, radically turning the valve up and down or on and off misses the point of saving energy. In circulation areas, it pays to try out whether the building's residual heat is sufficient. In addition, the energy efficiency of the heating system can be increased with hydraulic balancing, but this requires the skills of a specialist. Cost-intensive conversions, on the other hand, are more likely to be considered in the long term according to the current market situation; major work on the system is often then also due.