Fireplace Insert Installation in Los Angeles

A fireplace insert is a firebox in a steel or cast-iron body, with a glass door, that slides into the opening of an existing masonry fireplace. A surround panel covers the gap between the insert and the brick.

The gain comes from closing the opening. An open fireplace pulls room air into the fire and up the flue, taking heat with it, and most of what it does radiate comes off the front. An insert controls the air it burns and pushes heat into the room through its body and, on many models, a blower.

The masonry stays where it is, which is why an insert is usually less disruptive than building a new fireplace. The same fact creates the one requirement people underestimate: the old flue was built for an open fire, and an insert cannot use it as it stands.

An insert needs a properly sized liner connected to its outlet and run the full height of the chimney. The original flue was sized for the large opening of an open fireplace, and an insert's outlet is a fraction of that.

Venting a small appliance into a large flue lets the exhaust slow down and cool on the way up. With wood, that cool, slow smoke is what deposits creosote; with gas, it is what condenses into acidic water inside the chimney. Either way the draft is weaker than the appliance was designed for. A liner matched to the insert's outlet keeps the exhaust moving and gives the chimney a clean, sealed path to the top.

The size and type of liner are set by the insert's installation manual. Chimney liner installation covers liner types and how a chimney is relined, and what a chimney liner does explains the job the liner is there to do.

The firebox sets the limit. The opening's width and height at the front, the depth, and the width at the back (many masonry fireboxes taper) decide which inserts physically fit. The manufacturer lists the minimum firebox dimensions for each model.

Within the models that fit, heat output is matched to the room. An oversized wood insert gets run with its air turned down to avoid overheating the room, which is how it produces the most smoke and creosote. The manual also sets the hearth extension in front of the insert and the clearance to a wooden mantel, and an existing hearth that was fine for an open fire may not meet them.

An insert covers the firebox and a liner runs up inside the flue, so both become hard to see once the job is done. Their condition is established first. A chimney inspection looks at the flue, smoke chamber, crown and cap; loose or cracked firebrick is covered on firebox repair.

If the fireplace has burned wood, the chimney is swept before the liner goes in. Once an insert is running, its own upkeep is different from an open fireplace's; see fireplace insert cleaning.

An insert is the right answer when the house already has a sound masonry fireplace in the room you want to heat. The chimney provides the vent path, and the brick surround usually stays.

A new fireplace is the right answer when there is no fireplace in that room, or when the existing chimney is beyond economic repair. A direct-vent gas unit needs no chimney at all. Fireplace installation covers the options.

Under SCAQMD Rule 445, a wood insert permanently installed in the basin has to be an EPA-certified wood heater or a pellet heater. Neither may be burned on a no-burn day; a gas insert falls outside that restriction. In a home whose construction began on or after March 9, 2009, no wood-burning device may be installed at all unless an exemption applies. What the rule allows in full is set out on the installation page, and EPA Burn Wise explains what certification means for a wood heater.