Improving efficiency of the fireplace
Q. Our free-standing double-faced fireplace betweent the living and dining rooms, while beautiful, is very wasteful of wood. We use only mesh screens. It is 34 inches wide by 24 inches high and the flagstone hearths ar raised about 14 inches above the floor. What do you suggest? Jean Frank Gettyburg, Pa.
A. Existing fireplaces may be redesigned or modified to minimize energy waste. Several new concepts have been developed which increase the energy efficiency of conventional fireplaces.
Multifaced fireplaces present engineering problems that have to be solved before their energy efficiency can be improved. It may take an on-the-job inspection by a knowledgeable designer or mechanic to handle the needed changes on your existing unit.
Unless exterior combustion and draft air are provided, large amounts of expensive, artificially heated interior air are consumed during combustion.
New combustion and draft air intakes may be located in crawl spaces or behind or alongside the chimney. Even ash pits may be helpful as sources of outside air to feed the fire.
Inlets bringing in outside air to the firebox should be dampered to control air volume.
Keep the dampers closed when the fireplace is not in use.
Your fireplace with two openings will require separate sources of outside air for each opening.
When operating a fireplace, it is better that the mechanical heating system be turned down or off.
Fireplaces such as yours, located entirely within the structure, provide maximum thermal benefits. The masonry mass stores heat inside the house and radiates it even after the fire has gone out.
Glass fire screens are recommended. Close them when the fire is out or only smoldering.
The very efficient single- faced Rumford-type fireplace features widely splayed sides, a shallow back, and a high opening. Rumfords may not be able to be retrofitted to an existing fireplace in most cases.
For more specifics regarding the Rumford fireplaces as well as information on the retrofitting of existing fireplaces to achieve greater efficiency, get in touch with the Brick Institute of America, 1750 Old Meadow Road, McLean, Va. 22102. Phone (703) 893-4010. Ask for pamphlets entitled: BIA Technical Notes on Brick Construction, No. 19, and BIA Brick Builder Notes, No. 11.
Additional references are:
* "The Right Shape for the Right Fireplace," by the editorial staff of the Old House Journal, March 1976.
* "Book of Successful Fireplaces, How to Build them," Structures Publishing Company, Box 423, Farmington, Mich., October 1977.
* "The Measured Performance of Fireplaes and Fireplace Accessories," by Dr. Jay W. Shelton, Williamstown, Mass., 1978.
* "The Forgotten Art of Building a Good Fireplace," by Vrest Orton, published by Yankee, Dublin, N.H., 1974.
* "Book of Successful fireplaces -- How to Build, Decorate, and Use Them," 20 th edition, by R.J. Lytle and Marie-Jeanne, Lytle, published by Structures Publishing Company, Farmington, Mich., 1977.
* "The Brick-o-Lator, Brick Association of North Carolina, Greensboro, N.C., 1979.
* "Book of Successful fireplaces -- How to Build Them," 18th edition, by the D onely Brothers Company, Cleveland Ohio, 1965.