Most overhead closers have two or three adjustment valves and a power adjustment. Setting them correctly takes a few minutes and makes the difference between a door people accept and a door people wedge. One adjustment is off limits on a fire door, and it is the one most often reached for.
What each valve controls
The closing speed valve governs the main sweep from fully open down to the last part of the swing. The latching speed valve governs that last part, where the door needs a burst of speed to drive the latch home. Backcheck, where fitted, cushions the door near the fully open position so it cannot be flung into a wall. Power adjustment, on variable power closers, changes how much force the spring delivers overall.
The order to set them
Set power first, because everything else depends on it. Then closing speed, slow enough to be safe and fast enough that the door is shut promptly. Then latching action, fast enough that the latch engages every time from a narrow opening. Then backcheck if fitted. Re-test from several angles after each change, including a very small angle, because that is the condition that fails.
The adjustment that is never acceptable
Winding the power down until the door is easy to open but no longer latches. This is the single most common field modification and it turns a compliant door into a non compliant one in thirty seconds with a hex key. If the door is too heavy for its users, the answer is a different product, not a weaker setting.
When adjustment is not the answer
If the door will not latch at full power, the problem is elsewhere: a misaligned keep, a dropped leaf, swollen timber, a carpet fouling the bottom edge, or a closer at the end of its life. Adjusting harder against a mechanical obstruction wears the closer out and leaves the door failing.
Questions people ask about how to adjust fire door closer
Which valve stops the door slamming?
The closing speed valve controls the main sweep. Backcheck cushions the door at the open end. If a door slams it is usually closing speed set too fast, or latching action set too aggressively.
Can a caretaker adjust a closer?
Yes, with the manufacturer's instructions and an understanding that the door must still latch afterwards. The check after adjustment is the part that matters.
How often do closers need adjusting?
Whenever the routine check finds a door not latching, and after any work that changes the door, the floor finish or the ventilation in the building.