The O’Hara cooking fireplace in the pioneer log house, built in 2008, looks like it’s been there for 150 years. The massive structure, nine and one half feet in width, is constructed from stone taken from local mid-1800′s barn foundations. Cooking utensils hang on two blacksmith-forged swing arms once used in Madoc Township pioneer homes.
Unlike many of the fireplaces built by the early settlers, this one works like a charm. It has all kinds of updraft, preventing any smoke from entering the room. And it throws far more heat than was customary in pioneer times.
In all fairness, most early fireplaces were likely built in a hurry, often by people with little experience in the working principles of a good fireplace. Fortunately, for us, some good books have been written by New England stone masons who have specialized in improving the performance of pioneer-style fireplaces.
Many old fireplaces had a vertical back to the firebox, allowing the heat to go straight up the chimney, with a minimal amount getting into the room. The back wall of the O’Hara firebox rises vertically for one foot, then slopes inward at an angle that leaves about six inches of opening at the top across the full width of the firebox. This inward sloping deflects plenty of heat into the room.
There are some unforgiving rules that must be followed to create adequate draft e.g., to keep the fireplace from smoking. The flue opening should be at least one tenth the size of the firebox opening. The firebox opening at O’Hara’s is five feet wide and four feet in height, or 2,880 square feet, so we needed a flue opening 18 inchessquare. About eight inches above the lintel, there must be a smoke shelf at least one foot in depth. This shelf, at the bottom, is the full width of the firebox, and tapers in, over a height of three feet or so, to the width of the flue. The back of the shelf should be perpendicular to the back of the flue.
The pioneers did not have the luxury of firebrick, dampers, flue tile, inserts, heatilators, or glass doors at the front. The O’Hara fireplace is an example of a working cooking fireplace using only materials they would have had at their disposal with the exception of masonry cement, an improvement over the lime-based mortar of early times.
