Purpose of a Fireback
Stainless steel firebacks have been used for centuries. Their purpose is to reflect heat back into the room and protect the actual firebox from damage. Firebacks have been used since colonial times here in America. Originally they were used to protect the back wall of the firebox,. This because the backwall has often been susceptible to damage from very hot fires burning over long periods of time. Fire clay and other advancements in fireplace technologies have made heat from burning logs less detrimental to the firebox. However, damage can still occur. Placing a stainless steel radiant fireback in the firebox will protect it from certain damages.
Reflection of heat
The bricks in your fireplace are able to withstand extreme temperatures. With this aside, firebacks absorb a lot of the heat. This is so it safely dissipates and does not catch other materials in the construction of the chimney on fire. A stainless steel fireback will allow heat it absorbs by the back wall to reflect into the room. Experts say that the installation of a radiant fireback increases the efficiency of your fireplace by almost 50%.

Lots of Options
Although there are plain, stainless steel firebacks that are most widely available, there are also some truly beautiful decorative firebacks to add to the ambiance of your living room in general. With an about standard size firebox, say 28″-32″ by 46″-50″, you can allow between 5″ and 15″ on either side of the fireback without firebox coverage. You want the fireback, at minimum, to cover the back wall of the firebox directly behind the fire. If you have grates in your firebox which you set your logs on, this is a helpful indicator of the minimum size of fireback you need to purchase.
Cast Iron and Stainless Steel
Cast iron firebacks are the most sure protection for the back wall of your fireplace. Both cast iron and stainless steel firebacks provide protection for the back wall, however, and the stainless steel version are far less expensive in cost but generally do not come with the beautiful and intricate designs available for purchase in stainless steel. Cast iron firebacks usually come in a wider range of sizes than stainless steel firebacks.
The cast iron firebacks get warmth from the heat of the fire which then spits back into the room by the process of radiation. Since stainless steel firebacks radiate less heat than cast iron firebacks due to their smaller size, but reflect more light. You can either lean the fireback against the back wall of the firebox or stand it in metal brackets that sit on the floor. This raises up the fireback for better view by those in the room with the fireplace.

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