Overhead closers are the default for fire doors because the mechanism sits above the leaf where it is out of the traffic and can be sized properly. Within that there are three arrangements and several arm geometries, and the choice affects how the door feels to use as much as whether it closes.
Surface mounted
The body is screwed to the face of the leaf or the frame with a visible arm. It is the cheapest, the easiest to adjust and the easiest to replace, and it is visible. For most buildings it is the right answer, and the objection to it is almost always aesthetic. It is also the arrangement that can most easily be upsized later if the door turns out to need more power.
Concealed in the leaf or the frame
The body is morticed into the top of the leaf or into the transom, with a slide arm running in a channel. It looks better and it is harder to adjust, harder to service and more expensive to replace. On a fire door the mortice is a void in the core and therefore needs the certified intumescent protection, which is often omitted because it is invisible afterwards.
Arm geometry
A standard projecting arm gives the most power for a given closer size and projects into the opening. A parallel arm folds back against the leaf, projects less and delivers less closing power for the same size, which is why parallel arm installations are the ones most often found under powered. A slide arm gives a cleaner look and the least power of the three.
Adjustment and maintenance
Closing speed, latching action and backcheck are usually adjustable by valves on the body. Adjustment is a maintenance activity rather than a one off at installation, because seals bed in, buildings move and air pressure changes with ventilation. A closer that leaks oil is at the end of its life and is replaced rather than topped up.
Questions people ask about overhead fire door closer
Is a concealed closer as good as a surface one?
It can be, within its power range, and it is harder to specify correctly and harder to maintain. On a heavy door the surface closer usually wins on performance.
Which arm should be used on a fire door?
Whichever the doorset certification permits at a power size that closes and latches the door reliably. Parallel arms need a larger closer to achieve the same result.
Can a floor spring be used instead?
Floor springs exist in fire rated versions and are used on heavy doors and double action doors. They are a construction decision because the spring box sits in the floor.