Fireplace vs. Fireplace Insert: What's the Difference?

Updated October 8, 2026

A fireplace is a firebox built into the wall with its own chimney or vent. A fireplace insert is a sealed heating appliance that slides into a fireplace you already have and vents up the existing chimney. You buy an insert to get real heat out of an old open fireplace. You buy a fireplace when there is no firebox to start with.

The difference in one paragraph

An open wood-burning fireplace sends most of its heat up the chimney and typically runs at 5 to 15 percent efficiency. An insert closes that opening with a steel or cast-iron firebox behind sealed glass and runs at 60 to 85 percent. Inserts are made for gas, wood and electric. All three need an existing firebox to sit in, and direct vent gas and wood models also need a liner run up the chimney. If you are opening a wall or building new, a built-in fireplace is the right product, and it usually costs less installed.

Fireplace vs. fireplace insert at a glance

An insert only works if you already have a firebox

This is the question that settles most decisions. An insert has no framing, no outer shell rated to touch wood studs and no vent run of its own. It relies on the masonry or prefab firebox around it and on the chimney above it.

If you have a working fireplace and want heat from it, shop fireplace inserts. If you have a blank wall, shop built-in fireplaces: a direct vent gas fireplace vents straight through the wall, with no chimney work at all.

Why an insert heats and an open fireplace mostly doesn't

An open fireplace pulls room air up the chimney the whole time it burns, and it keeps pulling until the damper is closed. Most of the heat goes with it.

An insert is sealed. The fire burns behind glass, the firebox walls heat up, and on most models a blower moves that heat into the room. That is the gap between 5 to 15 percent efficiency and 60 to 85 percent. Our gas inserts run at 70 to 85 percent.

What each one costs

Starting prices per model at Dreamwood Living as of October 2026. These are for the appliance only.

Most electric inserts are well below the top of that range: 20 of the 23 we carry are $3,799 or less.

The appliance price is not the installed price

A direct vent gas insert needs a flexible liner kit and a licensed installer. Take the Majestic Ruby 30":

• Majestic Ruby 30": $3,109
• Chimney liner kit: $400 to $900, depending on chimney height
• Licensed installer for the gas line and liner: $600 to $1,500
• Total: $4,109 to $5,509

For comparison:

• Vent-free gas insert: no liner, usually $2,500 to $3,500 fitted.
• Built-in direct vent gas fireplace: a comparable model usually lands at $3,500 to $4,500 fitted, because there is no chimney work.

So an insert is rarely the cheaper route. What it saves is the fireplace and mantel you already have.

Will an insert fit your fireplace?

There is no standard insert size. The opening you already have decides which models fit. Measure three things:

1. Width across the front of the opening
2. Height at the front
3. Depth from the front edge to the rear wall. Measure to the back wall, not to the damper.

An insert fits when your opening is equal to or larger than the model's minimum on all three. Across the 21 gas inserts in our fit table, minimum openings run from 24-1/4" to 36-5/8" wide, 17-5/16" to 25-3/4" high and 14" to 19" deep.

Depth is the measurement that rules fireplaces out. Nearly every model needs 14" to 15" at minimum, and shallow prefab fireboxes often fall short. Many fireplaces also taper toward the back, so check the rear width where the manufacturer publishes one.

The downsides of a fireplace insert

• You pay for more than the appliance. The liner and the labor add $1,000 to $2,400 to a direct vent gas insert.
• The flame is smaller and behind glass. The insert sits inside the old opening, so the viewing area shrinks.
• A shallow firebox can rule it out. Under about 14" of depth, very few models fit.
• You commit to a fuel. A gas insert is built for natural gas or propane. It can be converted only if the manufacturer publishes a kit for that exact model.
• Vent-free models are restricted. Some states and municipalities ban them, and most codes prohibit them in bedrooms and bathrooms.
• It is the wrong product for a new wall. If you are framing anyway, a built-in fireplace costs less installed and comes in far more sizes.

So which one

Buy an insert if:

• You have a masonry or prefab fireplace and want it to heat the room.
• You want to keep the mantel, surround and hearth you already have.
• You are tired of hauling wood and want push-button gas in the same opening.
• The fireplace is drafty and you want the opening sealed.

Buy a built-in fireplace if:

• There is no firebox today, or you are opening the wall.
• You want a linear, see-through or multi-sided fire. Inserts don't come in those shapes.
• You want the lowest installed cost for gas heat.

Keep the open fireplace if:

• You light it a few times a year for the fire itself and heat is not the goal.

Not sure what will fit? Call us at 888-486-2909 with your three measurements and your fuel, and we will tell you which models fit your opening. You can also start with the fit table on our gas fireplace inserts page.