Pellet Stove Manufacturers Installation Of A Pellet Stove Insert?

Installation of a pellet stove insert? - pellet stove manufacturers

We install insert a pellet into the existing fireplace. The manufacturer, Harman, who teaches a steel plate must be installed with rock wool (mineral wool) in the chimney. The wool is very useful for the condensation, and the effects of flame retardants, but what is the purpose of the steel plate?