Installing Gas Fireplaces

Beth Asaff
gas fireplace on red wall

A gas fireplace is an excellent way to get the heat and ambiance of a traditional fireplace without the need to remodel or adapt your home with expensive masonry. This eco-friendly conversion can be done by converting a wood burning fireplace, installing a prefab unit or using a gas insert.

Gas Fireplace Options

There are several options available for homeowners who wish to have the ease and convenience of a gas fireplace in their home:

Wood Burning With a Gas Starter

A wood burning fireplace with a gas starter simply uses a gas line to ignite the wood, making the fireplace easier to use. This conversion can be done to any existing fireplace that burns wood. You will need a representative of your local gas company to come and run the line for you, but no other work is needed.

Gas Logs

A gas log fireplace can be the answer for numerous homeowners. Gas logs come in three options:

Converting a Wood Burning Fireplace

Conversions are a good idea if you rarely use your existing fireplace due to the hassle of using real wood. You will need to have a gas line run to the fireplace by the gas company, if you don't already have one, and then just hook up the logs by screwing on the coupling to the gas line. They come in a variety of styles and can mimic the look, ambiance and heat of a wood burning fireplace. The logs themselves run about $450, including the line hooked up by the gas company, so they are also an affordable option.

Prefab Gas Log Fireplaces

prefab unit built into drywall

Prefab units are complete gas log fireplaces that are installed near a wall that has a vent running through it. They look a lot like traditional fireplaces, and are frequently installed in the corners of rooms where they don't take up a lot of space, or they are built into the drywall of the room. They don't require a chimney or masonry to function.

Freestanding Gas Log Fireplaces

Freestanding gas log fireplaces are also prefab units. They can be installed anywhere there is a vent in a nearby wall, but they do protrude into the room.

Gas Insert

A gas insert is a steel-encased firebox that is positioned inside of an existing and usable masonry fireplace. They are vented through a pipe that moves the fumes up into the chimney and outside. If you look within the firebox, you see nice looking logs that serve only as a decorative element. Underneath, there are gas jets working to make the fire. Gas inserts are a great way to heat your home, reducing your dependency on the furnace, because they are so efficient. Many have an energy efficiency rating of 99 percent. Turn down the thermostat for the entire home and instead use an insert to heat those rooms of your home you are most often in.

Before Installing

Safety and Legal Issues

Once you have decided on the type of gas fireplace you plan to use, talk to the local building inspector and see what permits and inspections are required. Never skip this step as it can cost you a lot of money in fines later on.

Next, call your local gas or liquid propane supplier. Not only do most gas and LP companies sell the gas logs, inserts and prefab units you need, they are also the ones who will run the gas line to the fireplace for you.

Financial Concerns

You will also need the help of a licensed electrician for the various wiring; many gas fireplaces need an electric outlet nearby so circulation fans can run. By talking to these people ahead of time, you can better estimate the cost of your project. When you figure in all of the estimates, you may find that it is more cost effective to have a contractor do the installation, or that just having the gas company and electrician run the relevant lines is enough, and you can do the rest yourself.

Shop around at the local home improvement stores as well as online to find a fireplace to enhance your home. You can choose styles from contemporary to colonial.

Positioning the Fireplace

If you are not converting an existing firebox, but are installing a prefab unit, you will need to plan its position and size carefully. Make a mockup of the gas fireplace you plan to install. The mockup can be as simple as a sketch on several pieces of newsprint or as detailed as a poster board model. The important thing is to use the mockup to give you an idea of how the fireplace will fit in the room and where it should be located. This way you can plan for the visual effect as well as be sure that the heat from the fireplace will not be blocked by walls or other architectural details. You will also be able to plan for electric and gas hookups.

Find the nearest vent by going outside and checking your roof line. Look for a metal pipe or chimney sticking about 2-feet off the roof as close to the room you plan on installing the fireplace in as possible. The closer to this vent you can get, the cheaper your installation will be. Your fireplace must tie into this vent, or it will not function. If the vent cannot be tapped from inside, you will need to arrange your fireplace on an outside wall, and cut through the wall to the outside, running a vent up the outside wall.

Installing a Prefab Unit

Prefab gas fireplace

These instructions are for installing a prefab gas fireplace unit with an exterior vent. Interior vents must be tapped by a plumber or the gas company; contact them before cutting into the wall where the fireplace will be set.

  1. Read the manual that comes with your fireplace. Be sure you understand the instructions and have the tools needed to do the job properly.
  2. Follow the directions that came with the mantle kit. Put it together and set it aside.
  3. Find the center point on the wall where the hearth will be located. Use a pencil to mark the spot. Using a level, carefully transfer the mark to the floor.
  4. Set the mantle in place against the wall. Mark where you need to cut the baseboards. Move the mantle back out of the way and cut the baseboards. Check your center mark again to make sure it is still center and adjust if needed
  5. Place the firebox on the supports, centering it. Decide where the vent hole will be by using the template and measurements accompanying the unit. Set the vent in the position it will ultimately be in.
  6. Move the fireplace. Mark the wall where the vent will go. Use a 10-inch square cardboard template to mark the position.
  7. Cut through the interior wall and frame the opening with 2 by 4's. Using each corner as your mark, drill four holes through the external wall on the outside of the square.
  8. Fit the fire stop in the opening you have cut. Attach it with four screws. Seal it by caulking around it on both the interior and exterior walls.
  9. Attach the vent elbow by twisting and locking it into place.
  10. Connect the termination cap and set the fireplace in position.
  11. Finish connecting the external vent using the drilled holes as a guide to cut through the siding on your home. Fit the vent cap to the vent pipe.
  12. Mark the sheathing and cut it.
  13. Attach the vent cap to the hole with screws.
  14. Carefully seal the cap by caulking around the edges.

At this point the gas company and electrician will need to be called again to finish the electrical and piping work. When that is done, the building inspector will most likely want to take a look before you go on.

Finishing the Prefab Unit

The second part of the installation is putting the hearth and mantle in position. This is not difficult, but it does require a lot of attention to detail. When you put together a mantle from a kit, always follow the manufacturer's directions exactly.

  1. Support the mantle by attaching a 3-foot long 2 by 4 board as a header to the back wall. The header should be located just below the thick upper rim of the mantel. Be sure to connect it to the studs.
  2. Put the hearth extensions together and place the tile on the firebox. It must fit exactly to the front rim.
  3. Position the mantle. Attach it to the header with wood screws. Attach other screws as suggested in the directions.
  4. Caulk the seams between the fireplace and the mantle.
  5. Install the accessories including the logs, lava rocks and screen.

Installing a Gas Insert

Gas insert

The gas insert is installed inside an existing firebox. Make sure you contact the gas company and electrician to make sure all lines are run to the fireplace before you begin.

  1. Examine the back of the insert for the mounting plate. Use screws to attach vent pipes.
  2. Remove the fireplace damper and test fit the vent pipes to the chimney flue.
  3. Remove any ash covers that may exist on the floor of the fireplace.
  4. Attach the insert's legs and place the insert in the firebox.
  5. Use a level to make sure the insert is plumb and adjust the legs as needed.
  6. Have the gas company and electrician hook up the necessary lines at this point.
  7. Slide the insert fully into the firebox, taking care not to kink the gas line.
  8. Slide the mounting plates to the top and bottom of the insert and secure them with screws.
  9. Position the ceramic logs and other accessories according to the manufacturer's instructions.
  10. Install the surround.

Add Efficiency and Ambiance

A gas fireplace is a convenient and energy efficient way to add warmth and ambiance to a room. Upgrade your existing fireplace, or install a prefab unit today to see what you've been missing.

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Installing Gas Fireplaces