Is this brick wall continuous with the outside? or more of a decorative element inside?
When it come to retaining heat, two basic principles are used. The first is insulation...here the R value that insulation has refers to it "resistance" to heat flow. This is normally done by trapping air in some type of matrix. Whether this is fiberglass batts, cellulose, or bubbles in foam. The trapped air provides the Resistance.
The second main way to retain heat is to prevent "leakage" this is done by sealing air gaps, this can be done with caulks, spray foam, weather stripping etc.
Contrary to what many folk think a "traditional" fireplace can actually remove more heat from a room than it generates...if the fireplace has doors that can close and a secondary blower or heat transfer system then they will help, as do sealed wood stoves etc. an open hearth fireplace moves a lot of hot air up and out of the chimney. A lot of this hot air is combustion byproducts but a lot of "room" air is also sucked up the chimney pulling air from other parts of the home.
One way to evaluate your particular case is to have a home energy audit done...this will determine what your insulation and leakage conditions are. Once this baseline is established to can make improvements based on where the greatest needs are.
Thank you for the suggestions but this doesn't answer my question because
Brick is on inside,not decorative ( I think) Can feel cold on brick. Asbestos shingles on outside. What is transfer heating? Was told by company that installed new flue that everything is closed up top but a lot of cold air can still be felt. nay have baseboard heating on wall beside my sliding doors to deck..
doors or even a solid screen in front of the fireplace would help a little. a friend of mine closed off her fireplace and put a beautiful pot-bellied wood burning stove inside of it (it actually looks pretty neat) i already had a wood burning stove, and i framed, insulated, and sheetrocked around the rest of the room leaving the only brick area surrounding the stove itself. there often is not enough insulation in the ceiling-more could be added there. if re-doing the entire room is not an option even hanging fabrics and canvassed art will help insulate the room. its all about air pockets. good luck!
The cold air is coming out of chimney as a result of the exterior flue becoming cold from the outside causing the cold air to drop into the room.
If you do not have a damper just inside the chimney you can purchase foam boards and cut it to close off the front of the fireplace when its not in use. Just be sure that you put it in when you know for sure that the ashes from the last fire are cold.
here is a link for balloon damper sealer http://www.chimneyballoon.us/chimneyballoon.html
Other reasons why your cold is because there may be a lot of air getting around the edges of the brick. Wet the back of your hand on a cold evening and place it next to the wall where the brick meets up to it. Do you feel a draft? Bet you do. When we do energy audits we find air leakage in great amounts in this place. You will need to remove any trim boards if there are any and use caulk or slow rise spray foam if the gaps are larger and seal these openings. Once done replace the trim or even put new trim there from floor to ceiling where ever you feel this draft.
Also as KMS said. Get a home energy audit done. It will revel all sorts of things for you. If the company knows what there doing they can use a thermal imaging camera to locate missing insulation and the cause of the cold room as well. It is money well spent.
an Incense stick can also be used as a "leak or draft". I have know of some folks who have sealed off the top of "unused" fireplaces to prevent the cold air from dropping down the flue..
When a fire is burning all of the bricks will warn via conduction / convection. and provide some radiant warmth. This quantity of bricks provide "thermal mass"...warm when a fire is present cold when not being used.
Some fireplaces have "hollow" spaces built into the brick around the firebox etc. these area get warm and can provide for natural convective air flow that will heat the room, other are set up with a blower to make this even more effective.
In the photo below cool room air is drawn into the lower vents along the hearth....warmer air then exist the upper vents.