When the heating is on, most modern domestic boilers are designed to run at about 1.5–2.0 bar pressure as shown on the gauge. This is slightly higher than the “resting” pressure (usually around 1.0–1.5 bar when the system is cold and off).

Ideal pressure range (Quick Scoop)

  • Typical target when heating is on: around 1.5–2.0 bar on the boiler gauge.
  • Normal when heating is off and system is cold: roughly 1.0–1.5 bar.
  • Many boilers mark the “good” range in green and low/high danger zones in red, often below 1 bar and above about 2.5–3 bar.

In simple terms: if your heating is on and the needle sits somewhere around the middle of the green zone, that’s usually where it should be.

Always check your specific boiler’s manual, because the exact recommended working pressure can vary slightly by brand and model.