Masonry Magazine December 2012 Page. 22
FIREPLACES AND CHIMNEYS
Non-water soluble hydraulic-setting refractory mortar is a blend of dry Portland cement, dry fireclay, and dry aggregates. When mixed with water, it is not only heat resistant, but also acid resistant. This product is now the best all-around refractory mortar for fireplace and chimney construction. It is also the preferred choice for installation of the high-temperature resistant component parts for masonry bread ovens. It has the workability of a regular mortar mix, may have mortar color added to it, and is preferred if the joint thickness exceeds 1/8-inch. (By the way, always strike or finish smoothly the face of the joints, just like on a regular masonry wall, no matter the thickness of the joint.)
Non-water soluble refractory mortar is the only refractory mortar that should be used in outdoor applications. Premixed refractory mortars may wash out, even after drying. Due to the previously mentioned characteristics, non-water soluble product is the preferred choice for clay flue installations that may vent gas or oil appliances, or in any other instance in which moisture may be present within the clay flue. This is our overall refractory mortar of choice. It is used four to one versus other types of refractory mortar in residential construction.
Product Watch
# The ComfortGeni
The ComfortGeni model Geni 6xr is a through-wall fan that increases airflow from room to room or level to level, enabling building or home owners to enjoy the warmth from their fireplace or pellet stove in any room. With more than one-third of American homes using fireplaces as their primary heat source, it's important for home owners to ensure their appliances are ready for the upcoming fall and winter seasons. Because the Geni 6xr is a through-wall fan, most homeowners will require the expertise of a contractor for installation.
This new product also is not limited to residential use, and can be used in conjunction with any fireplace or HVAC system anywhere. The ComfortGeni is also eco-friendly and energy efficient. It has a built-in temperature sensor that automatically will shut the fan off when the source air temperature from a fireplace or wood stove is insufficient to create the desired temperature in the desired room. For more information, visit www.comfortgeni.com.
# Premixed refractory mortar
PREMIXED REFRACTORY MORTAR is a blend of clays, aggregates, and has a liquid silicate as a binder. Some masons prefer it simply because it is premixed, nothing needs to be added, and with a simple quick stir it is ready to use. Since the firebrick can be laid in place very rapidly (as with a firebox with firebrick joints 1/16- to 1/8-inch thick, for example) installation is a little quicker. Ten seconds after setting the firebrick, it takes some effort to dislodge them, and the fast-drying of the mortar does not compromise its strength like with regular mortar.
We usually recommend building Rumford firebox walls straight up, but premixed mortar makes building even a curved or slant firebox a breeze, because you don't have to form it or wait long for the mortar to set up. Premixed mortar can be a little messy to use, but remember, it is water soluble, so it cleans up easily with water.
You should butter a thin layer of refractory mortar on the firebrick that you are going to lay. Use a small margin trowel, because it fits in the bucket better than a pointed trowel. After applying a small amount on the firebrick, tap the firebrick in place so that the joint thickness is about 1/16-inch, and the excess mortar that oozes out from between the firebrick is removed with the margin trowel. Take your time and avoid the mess. The best thing is to lay a few firebricks, and then clean up the face of the firebrick with a sponge and clean water. The longer you wait to clean up the face of the firebrick, the harder it is to get all the particles saturated and removed.
In hot and dry climates we prefer the premised refractory mortar, because it does not seem to dry out as quickly as do other mortar types. Pre-wetting the firebrick helps if ambient conditions are hot and dry, no matter which type of refractory mortar is used. Even though there are some things that we prefer about the premixed products, the non-water soluble hydraulic setting refractory mortar is our first choice for all applications. In colder and damper climates, there is no question we like it better. IMAS
Jim Buckley is CEO at Buckley Rumford Co., www.rumford.com.
Bob Rucker is president of CMS Industries Inc., http://koppolay.com/Rumford/heatstop.html.
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