DIY Firebox Inserts

Use a measuring tape to obtain the width, height and depth of the opening. Measure the dimensions for the hearth. Carry the measurements to the supplier to ensure that you purchase the correct insert for the opening. Learn the building code requirement for installing fireplace inserts. Some codes require a licensed technician to perform some parts of the installation. Obtain a building permit for the project if required by the codes.

Have the chimney inspected by a fireplace expert to ensure that the interior is in good working condition. Make sure the flue or liner meets the size requirement to make the proper connection and guard against gas exhaust back drafting. Make repairs by installing a new stainless steel liner down the chimney. This is cheaper than attempting to repair the chimney's liner or a deteriorated flue. Use flexible liner that will go down the chimney easier; insert one end of the liner section into another, twist and lock. Use a rope or winch to lower the liner down the chimney.

Take the damper off the entry into the chimney. Removing the damper creates more wiggle room when installing the vent pipe leading from the insert. Detach the ash pit cover, located at the bottom of the opening; it may obstruct the insert installation. Make sure the insert fits into the opening before making any electrical or gas connections.

Shut off the electricity at the main distribution panel. Follow the wiring schematic to make electrical connections. Run the gas line with black pipe if a gas line is not present. Make sure the gas pipe has the correct diameter, a measurement that considers the length of the pipe run and the insert size.

Refer to the manufacturer's installation instructions and local building codes for guidance on this aspect of the installation. Install a gas shutoff valve within three or four feet of the appliance. Follow the instructions for attaching the insert connector to the chimney liner.