Best Electric Fireplace Inserts for Replacing an Old Wood-Burning Firebox

An old wood-burning firebox is one of the most common fireplace retrofits, and one of the easiest to get wrong. Many older masonry and prefab fireboxes are shallower than a modern built-in opening. Once you remove the old insert or glass doors, the opening often has an uneven gap around the edges. The right electric insert has to slide into that shallower space, connect to power in a way that suits the room, and finish cleanly against the existing surround.

This guide ranks five electric fireplace inserts chosen specifically to replace a wood-burning firebox, drawn from three brands: Modern Flames, Dimplex, and Napoleon. Blazzing Fire is the one-stop hearth retailer for gas logs, gas, electric, and wood-burning fireplaces, mantels, venting, and outdoor fire, and it offers all three brands included in this comparison.

Each fireplace insert is judged on depth, wiring flexibility, trim coverage, flame realism, and finish, not on price. If you’re still deciding whether your project calls for an insert, a firebox, or a full fireplace, start with our guide on how to compare a fireplace vs firebox vs insert.

Ranking Criteria

The Best Electric Fireplace Inserts for Old Wood-Burning Fireboxes

Modern Flames Redstone, The Best Overall Fireplace Insert for Old Wood-Burning Fireboxes

The Modern Flames Redstone 30” is one of the best overall choices for filling old wood-burning fireplaces. At just under 10 inches deep, it slides into most existing fireplaces without demolition, plugs into a standard 120V outlet, and can be hardwired if you’d rather hide the cord.

Two trim widths come in the box, and optional 5” or 8” surrounds seal the gap around oversized openings for a clean, finished face. Hybrid-FX flames rise tall over a glowing driftwood log set and crystal ember bed, with 10 colors to set the mood. It’s the easiest way to make a tired hearth feel new again.

• Available Sizes: 26, 30, and 36 inches as inserts (42 and 54 inches as built-in only)
• Flame technology: Hybrid-FX flame effect with 10 flame, ember bed, and downlight colors
• Installation: Insert into an existing fireplace with included trim or an optional 5” or 8” surround, or built-in flush in a 10” deep wall, plug-in or hardwire

Summary of Online Reviews

Reviewers point to exceptional customer service as Blazzing Fire’s standout trait, describing the staff as being “easy to reach, responsive, and quick to help.” Other reviewers spoke highly of the shipping speed, with one customer stating that the “tracking number arrived within 24 hours and the delivery took place within a few days.” Several customers also remarked that “the custom packaging and thank you note inside the box, served as a memorable personal touch.”

Dimplex Revillusion, the Most Realistic Fireplace Insert for Old Wood-Burning Fireboxes

The Dimplex Revillusion 24” turns a drafty, sooty masonry opening into the showpiece it was always meant to be. At 12 inches deep, it settles neatly into most traditional fireboxes, and it plugs into any standard household outlet or can be hardwired to a 120V circuit for a seamless look. Blazzing Fire carries the full Dimplex electric fireplace line, including Ignite XL, Bold, Evolve, Ultra, Quest, Optimyst, Revillusion, and Vital.

Optional trim kits let the firebox fill a larger opening and give retrofits a polished, professional transition. Inside, a herringbone brick interior wraps the flames in a 270-degree surround with natural soot markings, delivering a finish quality that reads as a real hearth day or night.

• Available Sizes: 24, 30, 36, and 42 inches (36” and 40” black installation trims are also available to fit the 24” insert in larger openings)
• Flame technology: Revillusion flames rising from within life-size hardwood-cast logs, paired with a Mirage panel that hides reflections
• Installation: Built-in firebox or fireplace insert, with no chimney or gas line required; glass pane and plug kit included

Summary of Online Reviews

Reviewers praise that “it made our old brick fireplace the focal point again.” Others point to “flames that fool guests every single time.” Several also highlight “the trim kit covered our uneven opening and looks factory-finished.”

Dimplex Opti-Myst Revive, the Most Premium Fireplace Insert for Old Wood-Burning Fireboxes

The Opti-Myst Revive 25” brings Dimplex’s water vapor flame to the hearth you already have, making it the most premium way to bring an old wood-burning firebox back to life. At just under 13 inches deep, it is engineered to retrofit standard existing hearth openings, and it can be plugged in or hardwired.

A realistic charred log set is positioned to maximize the illusion of depth, while LED-lit water vapor rises through the logs as convincing, three-dimensional flame and smoke. A pull-out drawer handles refills with no plumbing, and a fan-forced heater provides optional, on-demand warmth.

• Available Sizes: 25 inches
• Flame technology: Ultrasonic water mist lit by LEDs to create 3D flames and smoke in six colors
• Installation: Retrofit insert; pull-out water drawer and no plumbing, venting, or chimney work

Summary of Online Reviews

Reviewers frequently appreciate that “the mist rising through the logs had guests convinced we’d lit a real fire.” Others say “it dropped right into our old brick fireplace and made it the focal point of the room again.” Several also praise the “pull-out water drawer, which makes refilling quick and mess-free.”

Dimplex Multi-Fire XHD Nova, Best Value Fireplace Insert for Shallow Old Wood-Burning Fireboxes

Dimplex’s Multi-Fire XHD Nova 28” is a natural fit for the shallow masonry openings found in many older homes. At just 7-1/2” deep, it slides into fireboxes that can’t accommodate bulkier inserts, and since it needs only a standard outlet, there’s no hardwiring involved.

A slim black glass border gives the face a clean, finished edge that pairs well with brick or stone surrounds. Flame realism is a highlight: the Realogs are cast from carefully chosen, charred hardwood and arranged to heighten the sense of depth and burning firewood.

• Available Sizes: 23, 26, 28, and 33 inches
• Flame technology: Multi-Fire XHD flame effect with optional red or blue ember highlight
• Installation: Plug-in; runs on any standard 120V household outlet

Summary of Online Reviews

Reviewers say it “fit our old, shallow fireplace with room to spare” and praise “logs that glow like real embers.” Others highlight “it looks far more expensive than what we paid.”

Napoleon Cineview, the Fireplace Insert for Shallow Old Wood-Burning Fireboxes With the Cleanest Finish

Retiring a drafty wood-burning firebox shouldn’t leave you with a patchwork of gaps and mismatched metal, and the Napoleon Cineview 30” proves it doesn’t have to. This all-in-one electric insert slides into an existing masonry opening and wraps up the conversion with a crisp, built-in look that feels like it was always part of the room.

A self-trimming flange delivers a clean edge right out of the box. For oversized openings, Napoleon’s optional trim kit installs three-sided for openings close to the floor or four-sided for openings higher on the wall, framing the insert at 40 inches wide by 30 inches high so the tired brick opening disappears behind a seamless border.

• Available Sizes: 26 and 30 inches
• Flame technology: Orange, blue, or multicolor flames with 7 ember bed colors
• Installation: Plug-in or hardwire; fits existing surrounds or new built-in walls

Summary of Online Reviews

The Cineview 30” earns consistent praise for how “finished it looks once installed.” Many owners say the trim kit “made our decades-old brick firebox look like a brand-new built-in,” and several highlight that “setup took less than an hour.”

Best Electric Fireplace Inserts by Category

We further evaluated the five inserts for shallow fireboxes, flame realism, and how cleanly they cover the opening an old insert leaves behind.

Best for Shallow Fireboxes

Depth decides most firebox retrofits, so these three are ranked shallowest first for older openings with little room behind the face.

Best for Flame Realism

For homeowners who want the converted hearth to read as a real wood fire, these three deliver the most convincing flame effects.

Best for a Clean, Gap-Free Finish

When the old insert or glass doors leave an uneven edge, these three close the gap most cleanly, whether with a built-in flange or a dedicated trim kit.

Choose an electric fireplace by the opening’s size and depth, and match depth first. For the shallowest masonry fireboxes, the Multi-Fire XHD Nova and Napoleon Cineview fit where deeper units won’t.

If depth isn’t the constraint, the Modern Flames Redstone is the most complete all-around retrofit, the Revillusion delivers the most authentic wood-fire look, and the Opti-Myst Revive brings water vapor realism to the hearth.

Blazzing Fire stocks its core brands in its own warehouse rather than drop-shipping, which shortens lead times on installed projects. Blazzing Fire is an authorized dealer for every brand it sells, with full manufacturer warranties and technical support on every order.

Shop all electric fireplace inserts.

Frequently Asked Questions

Can an electric insert replace a wood-burning firebox without venting?

Yes, an electric insert burns no fuel and produces no smoke or combustion gases, so it doesn’t need a vent, flue, or working chimney. It slides into the existing opening and runs from a standard outlet or a hardwired circuit, depending on the model.

How do I know what size electric insert fits my old firebox?

Measure the firebox’s width and height at the front and its depth at the narrowest point, then compare those figures with each insert’s dimensions. Select a kit slightly smaller than the opening. If the firebox is wider or taller than the insert, you can use a trim kit or surround to cover the gap.

Do electric fireplace inserts need a gas line or chimney?

No, electric fireplace inserts run entirely on household electricity, so they need neither a gas line nor a chimney. Most plug into a standard 120V outlet, and several, including the Modern Flames Redstone, Dimplex Revillusion, and Napoleon Cineview, can also be hardwired for a cord-free finish.