Summary: Learn how to drain a central heating system, drain the radiators, re-fill the central heating system and re-fill the radiators.
Various repairs to your central heating system will require you to drain the system. The following method is suitable for an open-vented system, which is the most common type of system installed today.
If you cannot find a stop-tap or it is too stiff to undo, place a length of wood across the top of the cistern and tie the ballvalve to it.
Open the drain valve by turning it anti-clockwise.
On the lower floor open up one of the radiator air vents and when water comes out in a steady flow, close it.
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