The purpose of the fireplace damper is to keep the outside elements, outside. The damper is opened only when there is a fire in the fireplace.
the flue should be opened
To properly close a fireplace flue, you should make sure the damper is fully closed and secure. This helps prevent heat loss and drafts when the fireplace is not in use.
You close the damper when you are not using the fireplace too keep air from coming in and to keep the air from being sucked out. This is most important in the winter. You don't want cold air coming in and your heat sucked out. When you are using the fireplace you have to open the damper to allow the smoke and fumes to escape.
Then you have a shortage of combustion air, and it is drawing air down the unused fireplace flue. Close the damper of the unused fireplace, and check for exhaust fans that may be drawing air out of the house.
If the damper should close while a fire is burning, all of the smoke will be coming out in the house- NOT a good thing. Most dampers have a hold-open device held in place by gravity.
To properly close a fireplace for safety and efficiency, make sure the damper is closed when the fireplace is not in use to prevent drafts and heat loss. Use a fireplace screen or glass doors to contain sparks and embers. Keep the area around the fireplace clear of flammable materials. Have the chimney inspected and cleaned regularly to prevent buildup of creosote, which can cause chimney fires.
It closes by itself.
The main thing that one should do to make sure that heat is not being lost through the chimney of a fireplace is to always close the damper when the fireplace is not in use. In addition, you can also use a fireplace door or cover to prevent additional heat loss.
its a automatic door which open and close by itself when the people want to pass it through..
There are many kinds of dampers, depending upon how old the house is and the choice by the masons. Many dampers have a hinge on the rear and a handle that can be pushed or lifted to lift the front and latch it open. Others have a lever designed to move with a knob or chain connected to the damper. Some chimneys have counter-balanced dampers on the top of the chimney that are opened by pulling and latching a chain. A "tilt and slide" damper not only opens with a handle, but also has a movable grating that can be "slid" open and shut using a knob cast into it. If you have a gas log fireplace and can not close your damper by the handle it is very possible that the damper has been disabled or welded open according to the 1991 building code that states that dampers in new gas log fireplaces must be disabled. The only type of damper that is allowable to use in a gas log fireplace is an inflatable damper. If you do not have a gas log fireplace and you cannot open or close your damper it is likely that it has corroded to the point of non-function. The chimney is a very acidy and corrosive environment any metal in it will rust and degrade rapidly over time. Lubricate the damper with a penetrating oil and try to loosen it by hand or call a chimney sweep to come and work on it.
A top damper or cap damper is a metal spring door placed at the top of the chimney with a long metal chain that allows one to open and close the damper from the fire place.