The boiler industry has long recognised the advantages of full modulation, and it is surprising that systems without stepless modulation are still used, especially in energy-intensive industrial buildings. Example radiant tube heaters: Conventional tube heaters often operate with a fixed output. The adjustment to the required heat demand is only controlled by a cycle (on/off) of the burner. But this results in some major disadvantages: The energy efficiency of the burner decreases in these switching cycles and the pollutant emissions increase significantly.
The solution is a continuously modulating system, i.e. a gas/air combination that can vary the burner output within a wide range. For this purpose, not only the fuel quantity but also the combustion air is adapted to the respective power requirement. In this way, the best combustion in terms of energy and the highest radiation factor (even in partial load operation) can be guaranteed.
The advantages of simultaneous adjustment of fuel and combustion air:
- Increase in overall energy efficiency by adapting fuel and combustion air to the heat demand required.
- High annual efficiency: the lower flue gas temperature in part-load operation results in a lower flue gas velocity. The exhaust gas flows more slowly through the system, leaving more time for heat to be transferred to the system
- Pollutant reduction: the reduced cycling reduces the formation of unburned pollutant components, which are produced especially when the system is started.
- Prevention of heat loss: since the system does not have to be restarted, the mandatory “purging” with fresh air is eliminated. This allows unnecessary heat losses to be reduced.
Due to these advantages, modulating tube heaters are rated up to 5% better than non-modulating devices when determining the seasonal energy efficiency (Ecodesign Regulation EU2015/1188).
