Control

There is also great potential for savings in optimising and adapting the control of hot water boiler systems to actual operation. This optimisation is always advisable, as the design conditions and actual operating requirements of boiler systems differ. This is already the case for new installations, as there are safety margins in the design with regard to the required temperature level or the heating surfaces of the consumers, or even if, for example, additional consumers have been installed retrospectively. Even for existing systems, if the current operation has changed due to conversion and expansion of production, we recommend adjusting the control system.

Setting back the flow temperature

When designing and dimensioning a hot water boiler system, a target flow temperature is determined based on the required temperature levels of the individual heat consumers. However, this design is often very conservative and includes appropriate safety measures, which means that a slightly lower flow temperature would also be sufficient in actual operation.

For energy optimisation during operation of the system, and particularly when changes are made to the system, it is therefore advisable to determine the minimum flow temperature actually required and set this on the boiler control. Setting back the flow temperature reduces the temperature in the boiler and the connected pipes, thereby reducing radiation and conduction losses.
In modern, large hot water and heating systems, not only are external temperature influences taken into account via the heating curve in the control system, but the actual minimum required flow temperature of all connected consumers is determined for each operating condition throughout the year and specified as the target flow temperature for the boiler.

Setting the flow temperature back by approx. 5 °C reduces heat loss through conduction and radiation by 3 %, resulting in fuel savings of around 0.1 %.

In addition to heat losses, the flue gas temperature is also slightly reduced, which further improves the annual efficiency.

Even outside the main operating hours of a hot water boiler system (e.g. at weekends), the maximum flow temperature is not always required. In such cases, it often makes sense to set the flow temperature to a lower level.

Boiler sequence control

If several hot water or heating boilers are installed in a facility, the respective operation of the single boilers can be optimised via a boiler sequence control system.

The job of a boiler sequence control is to activate only as many boilers as are required to cover the current power requirement. This adjustment is achieved by automatically switching the follow-in boilers on and off according to the criteria of the sequence control. Economical and gentle operation of the boiler system is guaranteed. By optimising the boiler sequence to match the actual power requirements, pre-purging losses are reduced, boilers are automatically switched to warm-up mode, and boiler-efficiency-optimised operation can be achieved. These adjustments and the resulting reduction in heat loss improve the annual efficiency.