The best way to tell whether or not the damper is open is to check the controls.
Fireplace damper handle which way is open.
Operating the fireplace with the damper partially closed will not.
Fireplace dampers are typically made of metal or ceramic so they can tolerate the heat of the fire without suffering damage.
The damper can be opened and closed through a few different mechanisms including a latch a pull chain or a handle.
Carry out a visual check.
Fireplaces are constructed fairly simply.
If your chimney has a traditional throat damper it will either be controlled by a metal rod or a knob also called a rotary style.
Damper controls are usually located near the top of the firebox.
As a rule the operating mode for a damper is about one fourth of the way open.
The damper should always be fully open before lighting a fire and when the fireplace is in use.
If the flue is open the smoke will go out of the chimney without any problem.
A damper plate located at the top of a chimney within a top mounted damper is usually square in shape and spring loaded to open or close via a pulley chain with the chain handle to control the damper located within the fireplace.
These dampers are open by lifting the handle up pushing the damper upwards and pinning the damper in the upward position by setting one of the notches on the handle onto the mounted ratchet on the frame of the fireplace.
You can look up into the chimney and see it open and close.
If the damper is closed then the smoke will come out of the chimney and fill out the room.
Optimal temperatures vary by house.
Check up into the chimney from your fireplace.
How your damper is controlled depends on the type of damper your chimney has.
Test out the damper when the fireplace is not in use to get a feel for how it works.
This is a good way to get a feel for how the damper and its controls work.
This kind damper poker dampers we commonly refer to as a banana handles this is because of the banana shape arch in the handle.