Masonry Magazine January 1984 Page. 31
The firebox and all other components constructed of refractory units should be placed using a fireclay mortar conforming to ASTM C 105, medium duty. Other refractory mortars have also been used successfully, and thus any high temperature-resistant mortars that have performed well may be used. It is not within the purview of the Brick Institute of America to recommend proprietary products. The selection of the proper mortars should be determined by an experienced fireplace expert for the specific design being considered. Grout is required for reinforced hollow walls and reinforced hollow brick construction. Such assemblies must be fully grouted. The grout should conform to ASTM C 476.
Steel Lintels and Dampers
Steel lintels should be used only above the firebox opening because of the high temperatures occurring within the heater. The thermal expansion characteristics of the different materials could cause cracking of the brick masonry heater. Lintels of corrosion-resistant steel, conforming to ASTM A 36, should be used to span over the firebox door openings. Non-combustible, compressible material should be placed at the ends of all lintels to provide for differential thermal movements.
Ties and Reinforcement
Corrugated Metal Ties. Corrugated metal ties may be used to anchor the baffles to the interior wythe of the heater walls and to tie the two wythes of the exterior walls of the heater. Ties should be corrosion-resistant, approximately 22 ga, % in. (22.2 mm) wide, and 6 in. (150 mm) long. Stiffer ties should not be used, as they may transfer stresses due to thermal expansion of the interior wythe to the exterior wythe of the brick masonry heater.
Prefabricated Joint Reinforcement. Prefabricated joint reinforcement should be used only in the exterior wythe of the heater walls. The joint reinforcement should be fabricated from wire which complies with ASTM A 82 or ASTM A 185, and must be corrosion-resistant.
Reinforcement. Reinforcement should conform to any of the following applicable standards:
Standard Specifications for Deformed Billet-Steel Bars for Concrete Reinforcement-ASTM A 615
Standard Specifications for Rail-Steel Deformed Bars for Concrete Reinforcement-ASTM A 616
Standard Specifications for Axle-Steel Deformed Bars for Concrete Reinforcement ASTM A 617
Corrosion Resistance. Corrosion resistance is usually provided by a copper or zinc coating, or by using stainless steel. To ensure adequate resistance to corrosion, coatings or materials should conform to any of the following applicable standards:
Zinc-Coating of Flat Metal-ASTM A 153, Class B-1, B-2, or B-3
Zinc-Coating of Wire-ASTM A 116, Class 3
Copper Coated Wire-ASTM B 227, Grade 30 HS
Stainless Steel-ASTM A 167, Type 304
Firebox Doors
The doors for the firebox opening may be fabricated locally, ordered from Europe, or may be conventional, metal Dutch oven doors, which are the most economical. The brick masonry heater is not designed for air-tight combustion and thus the doors need to be equipped with operable vents to control air intake into the firebox. The size of the firebox opening is determined by the size of the firebox door used. Other alternatives which exist for the firebox design and firebox doors are discussed in other Technical Notes in this Series. Glass screens may be used, but they must be capable of withstanding the high temperatures and severe exposure occurring within the firebox.
Clean-Out Doors
Conventional clean-out doors may be used, but to ensure tightness, refractory units should be placed within the door opening with a compressible material or set in a sand-lime mortar. The refractory units increase the resistance to combustion gas leaks, provide protection to the metal door from high temperatures, and may easily be removed and replaced when cleaning. This is shown in Technical Notes 19D. Clean-out doors for the ash drop may be conventional clean-out doors, installed in the conventional manner.
SUMMARY
The information and suggestions contained in this Technical Notes are an accumulation of the available information within the Brick Institute of America on brick masonry heaters. The information is based on empirical data from actual performance of such heaters here in North America and in Europe. The information provided in this Technical Notes and Technical Notes 19D does not address all of the possible variations, or alterations, which may be incorporated into a brick masonry heater by design or construction requirements. The information and recommendations provided in this Technical Notes discuss the basic principles and guidelines by which fireplace experts using good technical judgment may design and construct a functional brick masonry heater.
Final decisions on the design and use of materials, as discussed in this Technical Notes, are not within the purview of the Brick Institute of America and must rest with the project designer, owner, or both.
ACKNOWLEDGEMENTS
The assistance provided by Mira Wisniewska, of Technical Translation International, Limited, 500 Fifth Avenue, Suite 200, New York, New York, 10036, who translated the articles listed in References 1 through 5, 11