Bleeding a radiator

In short: If the radiator gurgles or stays cold at the top, there is often air in the system. With a bleed key you let the air out at the valve until water emerges.

In more detail: Air in the heating circuit hinders water flow and worsens heat output. That raises heating costs.

In detail

• When: At the start of the heating season and when noises or cold spots appear.
• Preparation: Turn the heating fully up, briefly switch off the circulation pump, have a cloth and a container ready.
• Procedure: Open the bleed valve a quarter turn with a square key. When air hisses until water comes, close it again.
• Check pressure: Afterwards check the system’s water pressure on the gauge and top up water if needed (usually 1.0 to 2.0 bar).
• Help: In apartment buildings and with underfloor heating have a specialist do it (heizkosten-senken-und-richtig-heizen, waerme-und-temperatur).