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How to Install a Gas Fireplace Insert

Upgrade your old wood burning fireplace with a more convenient gas fireplace insert.

In this video, This Old House plumbing and heating contractor Richard Trethewey upgrades an old wood-burning fireplace by installing a gas fireplace insert.

Want to turn on your fireplace at the push of a button? To make this upgrade to your existing fireplace, you can install a gas fireplace insert.

Since this process requires working with vent pipes, electrical, and the gas supply, we recommend working with a professional instead of doing it yourself. In the video above, and step by step instructions below, we show you how to install a gas fireplace insert step-by-step.

How Much Does It Cost to Install a Gas Insert Fireplace?

Gas fireplace insert installation costs start at about $500 and up. This depends on the size of the fireplace. According to Home Advisor, the gas fireplace insert itself can cost about $2000.

How to Install a Gas Fireplace Insert in 15 Steps

  1. Run electrical power to fireplace and install a duplex receptacle.
  2. Remove existing chimney cap and damper from top of chimney.
  3. Drop both airflow intake and exhaust liners down the chimney flue.
  4. Use high-temperature silicone sealant to secure top plate to chimney top.
  5. Screw a termination fitting onto ends of the liners.
  6. Install a weatherproof cap onto the termination fitting.
  7. Insert a chimney cap into the furnace flue.
  8. Run new gas line to fireplace.
  9. Connect a flexible gas-supply line to gas line in the fireplace.
  10. Plug in the power cord from the fireplace insert.
  11. Make final gas connection between flexible gas-supply line and fireplace insert.
  12. Slide the insert into place, then turn on the gas.
  13. Make exhaust and intake connections at top of insert using high-temperature silicone sealant.
  14. Install glass doors to the fireplace insert.
  15. Test fireplace insert using the remote control.

Tools and Materials