An electric fireplace insert for an existing fireplace is the simplest way to turn a drafty, rarely used wood-burning or gas firebox into something you will switch on every night. You keep the mantel and surround, slide an electric firebox into the opening, plug it in and get a flame effect with optional heat and no venting. This guide covers how inserts work, how to measure, what has to happen to the old fireplace first, the honest pros and cons, and which Amantii units we carry that are built for this kind of retrofit. For the bigger picture on built-in, linear and wall-mount units, see our electric fireplace buying guide.
How an electric fireplace insert for an existing fireplace works
An insert is an electric firebox sized to sit inside a masonry or prefab fireplace opening. It produces an LED flame picture and, when you want it, fan-forced heat. Amantii’s FAQ says its electric fireplaces are vent-free and need no chimney, venting or gas line, and that there is no open flame or cleanup. A trim kit or surround covers the gap between the insert and the edges of the opening so it looks built in.
Amantii sells dedicated insert lines on its own site, including the TRD Bespoke Insert in 26, 30, 33 and 38 inch models with 3-sided or 4-sided trim made from 22-gauge metal, and the TRD Lumina Insert. If one of those is what your opening needs, call us and we will check availability. From our in-stock range, the units below are the ones whose listings describe insert or existing-fireplace installs.
Amantii units we carry for fireplace retrofits
| Model | Price | Listed heat | Notes from the listing |
|---|---|---|---|
| Zero Clearance Square 31 in (steel surround) | $1,518 | 4,800 BTU, 400 to 500 sq. ft. | Described as installing into an existing fireplace or new construction; cast log set; Low, High and Auto heat; plug-in or hardwire |
| Zero Clearance Arched 31 in | $1,267 | 4,800 BTU | Arched heavy-gauge steel surround, deep tray, cast log set; plug-in or hardwire |
| Zero Clearance 26 in | $968 | 4,800 BTU, 400 to 500 sq. ft. | Log set plus ember or ice media; plug-in or hardwire; optional white surround |
| Zero Clearance 33 in | $1,298 | 400 to 500 sq. ft. | Top-vented heater; glowing log set; ember or ice media |
| Traditional XtraSlim 30 in Smart | $1,499 | 750W low, 1500W high, up to 400 sq. ft. | Wi-Fi app control; recesses into a 2 x 4 wall or mounts |
| Traditional XtraSlim 33 in Smart | $1,699 | Two heat settings, up to 400 sq. ft. | Wi-Fi app control; 11 up-light colors |
The Zero Clearance models are the closest to a classic square or arched firebox look. The Traditional XtraSlim units are slimmer and add app control; our listings call them inserts, but they are designed first as recessed wall units, so measure carefully if you plan to set one inside a masonry opening.
Step 1: measure the opening properly
Most fireplace openings are not simple boxes. Masonry fireboxes usually taper toward the back and sometimes slope at the top. Take these five measurements before you shop:
- Front width at the face of the opening.
- Rear width at the back wall, which is often several inches narrower.
- Height at the front, and again at the back if the top slopes.
- Depth from the face to the back wall, measured at the narrowest point.
- Distance to the nearest outlet, so you know whether the cord reaches.
The insert’s body has to fit the rear width and the shallowest depth, not just the front. The trim then needs to be larger than the front opening so it covers the gap. Send us all five numbers and we will check them against a specific model’s manual before you order. Never assume a built-in firebox will fit a masonry opening without that check.
Step 2: get the old fireplace ready
Electric fireplace insert for a wood burning fireplace
If the fireplace has been burning wood, have the chimney swept and the firebox cleaned first so soot and debris do not fall onto the new unit. Close the damper to stop drafts. Many homeowners also seal the flue with a chimney balloon or a top-sealing damper, since an open flue pulls warm room air up the chimney whether or not a fire is burning.
Converting a gas fireplace
If the fireplace has a gas log set or burner, the gas supply must be shut off and capped by a licensed gas fitter before an electric insert goes in. Do not do this yourself, and do not leave a live gas line inside the firebox.
Step 3: power and wiring
The models above can be plugged in, and the Zero Clearance units are also hardwire ready. Many older fireplaces have no outlet nearby. Your options are to run the cord out of the opening to a nearby receptacle, or to have an electrician add an outlet in or beside the firebox. A heater running at 1,500 watts on 120 volts draws about 12.5 amps, which is most of a standard 15 amp circuit, so many installers prefer a dedicated circuit. Follow the unit’s manual and your electrician’s advice; never use an extension cord or power strip.
Amantii’s FAQ also states that no permits are required for its electric fireplaces. Rules vary by city, so check with your building department if you are adding a circuit or changing the gas line.
Electric fireplace insert pros and cons
| Pros | Cons |
|---|---|
| No venting, gas line or chimney needed for the insert itself | Heat is supplemental, rated for one room (about 400 to 500 sq. ft. on the units above) |
| Flame can run without heat, so it works in summer | The flame is an LED picture, not a real fire, and there is no wood smell or crackle |
| No ash, smoke or chimney fires from the insert | Older fireplaces often need an outlet or new circuit |
| Keeps your existing mantel and surround | Tapered or very shallow openings can limit model choice |
| Amantii’s FAQ puts average running cost at about $0.02 per hour without heat and $0.07 per hour with heat | Running cost depends on your local electricity rate, so treat that figure as Amantii’s estimate |
Choosing media and finishing touches
Most of the Zero Clearance units include a log set and let you choose ember or ice media. If you want a more traditional look, the Amantii 10-piece birch log set and other log sets on our Amantii brand page swap in easily. For more on how the Amantii series differ, read our Amantii electric fireplace review, and if you are cross-shopping brands, our Amantii vs Dimplex comparison covers warranties and app control.
Ordering and support
Orders of $999 or more ship free by freight; below that, shipping is a flat $200. Returns follow our return and refund policy. Call 866-777-2590 (Mon to Fri, 9AM to 6PM PST) with your five measurements and a photo of the opening, and we will help you pick a unit that fits.
Frequently asked questions
Can you put an electric insert in a wood burning fireplace?
Yes. Clean and inspect the firebox and chimney first, close the damper, and make sure the insert’s body fits the rear width and depth of the opening. The trim covers the gap at the front.
Do electric fireplace inserts need a chimney?
No. Amantii says its electric fireplaces are vent-free and need no chimney or venting. Many owners still seal the existing flue to stop drafts.
How much heat does an electric fireplace insert give off?
The Amantii Zero Clearance units we carry list 4,800 BTU for 400 to 500 sq. ft., and the Traditional XtraSlim units list 750W and 1,500W settings for up to 400 sq. ft. Treat that as supplemental heat for one room.
Do I need an electrician to install an electric fireplace insert?
Not if a suitable outlet is within reach and you plug the unit in. You need an electrician to add an outlet or circuit or to hardwire it, and a licensed gas fitter to cap a gas line.
What are the main electric fireplace insert pros and cons?
The pros are no venting, no ash, flame without heat and an easy retrofit. The cons are supplemental rather than whole-home heat, an LED flame rather than a real one, and possible wiring work in older fireplaces.
