What is modulating heating control? What are the benefits over a relay (On/Off) control?

The most common heating system control interface by far is still the On/Off control via a relay. It allows a controller to request either none or full heating power. Advanced algorithms enable a good control of the room temperature with a relay, however, the system is balancing between efficient heating and good temperature control. Modulating control, on the other hand, allows to increase or reduce the heating power to the actual required output and therefore allows efficient heating control and high comfort at the same time. Most modern heating systems allow some type of analog or digital heating control.

Modulating control has the following advantages when compared to a traditional relay On/Off control:

  • Higher comfort levels are achieved because there is less fluctuation in the room temperature, especially at moderate outside temperatures.
  • The average boiler output temperature is lower which increases the efficiency of the boiler.