Chimney damper advantages
The chimney damper is used to retain hot air inside the house when a fire isn’t lit in the fireplace. There are many modern types of chimney dampers that have adjustable lids.
The chimney damper, and especially the damper with a rubber seal, will prevent the entrance of any small animals that could formerly enter the chimney and do damage to it or block it.
Heating and cooling costs
The chimney damper will reduce your heating and cooling bills. It will retain hot air inside the house instead of letting it rise and exit through the chimney like it normally would.
An open damper will feed oxygen into the fire so it will make it bigger and more efficient. After the fire has been lit and is big enough, you must close the damper, and the fire will retain its force.
A chimney damper will allow a much better smoke control. Smoke is always an issue when tending a fire or putting it out.