ThisK-23 insulating firebrick (IFB) is a lightweight, porous refractory brick designed for high-temperature furnace and combustion chamber applications. Lynn MFG# 3123 K-23 Insulating Firebrick. Unlike dense firebrick, K-23 bricks heat up quickly, improving system efficiency and reducing fuel consumption in gas, propane (LP), or oil-fired heating systems.
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