Electric fireplace inserts for existing fireplaces: fit, features & costs
The right insert starts with the opening you already have. Compare four documented options, understand the trim and check the electrical requirements before buying.
By the Renology editorial team Source research updated
An insert should fit the opening and the way you use it
Check the cavity, trim and electrical supply before comparing flame effects.
An enclosed electric firebox gives an existing fireplace a new front. An open log set leaves more of the original firebox visible. The four options below cover both approaches, with exact model references and links to the source documents.
We have not lab-tested these products. This comparison focuses on documented installation differences, price scope and practical questions, rather than declaring a “most realistic” or “quietest” winner.
Choose the kind of fireplace you want to keep
Enclosed firebox
Napoleon Cineview, Modern Flames Redstone and Regency Ei29 provide an enclosed appliance front. A trim or faceplate can cover the surrounding gap, but cannot make an undersized cavity larger. Confirm that the chosen model and installation method are approved for your existing fireplace.
Open log set
Dimplex RLG25 places an electric log display inside the opening. The existing firebox stays part of the appearance, so the condition, interior shape and viewing angle deserve attention. A log set and an enclosed insert are different aesthetic and installation choices.
Measure the space, not the product name
A “26-inch” model name does not describe every dimension needed for installation. Record the front width, rear width, height and usable depth. Then check the selected trim, clearances, power connection and instructions for the specific installation type.
What the measurements mean
Front width: clear space between the sides at the opening.
Rear width: available width where the appliance body will sit.
Height: the smallest usable opening height, including any arch.
Depth: usable space from the front plane to obstructions behind it.
What numbers alone cannot tell you
A tapering firebox, projecting lintel, uneven hearth or cord location can change the result. Trim coverage, ventilation, service access and combustible clearances remain separate checks. Photograph the opening and bring the measurements to the installer or dealer.
Opening dimensions, outside appliance dimensions and viewing-area dimensions are different. The comparison labels which kind of measurement each source provides.
From the front
Looking down from above
Renology measurement schematic, not to scale. Measure the clear front width, narrower rear width, smallest opening height and usable depth. Your firebox may have a different shape. Clearances, trim and the cord route still need a separate check against the model manual.
Keep your opening measurements together
Measure the clear opening, including the narrower back and any obstructions. Record the smallest usable dimensions. This worksheet converts units; it does not approve a model for installation.
Enter four positive measurements to see the converted dimensions. No product is marked as fitting from these numbers alone.
Compare four options for an existing opening
Choose two for a detailed comparison. Prices are in US dollars and exclude any unlisted installation work. Dealer-quote entries are not treated as cheaper or more expensive than the published base price.
4 options shown · 0 of 2 selected
Opening references use different configurations. Confirm fit against the full model manual. Select two for a detailed comparison.
Two selected options. Keep the price and dimension basis attached to each figure.
Compare
Price
Exact model
Opening reference (W × H × D)
Power
Connection
Finishing
Ask before committing
These dimensions are screening references, not a fit guarantee. Regency’s figures apply to the named trim configuration. Dimplex’s figures describe an optimal viewing opening. Always use the exact model’s complete current manual.
The differences that matter before ordering
Napoleon Cineview 26
$769Manufacturer starting base price, USD
A shallow firebox to investigate when depth is tight. The included logs and crystals let you change the appearance without buying another media set.
Keep in mind. The product page has inconsistent power descriptions. We use the model-specific manual: 120V and 1,465W. Have the dealer confirm the manual supplied with your unit before specifying electrical work.
A compact Redstone model with a documented opening table. It can be considered for an existing opening or a built-in installation, with different installation steps.
Keep in mind. The product name, firebox body and trim describe different dimensions. Do not use the larger trim width as the minimum cavity width.
Dealer quoteChoose faceplate and electrical configuration
An option to investigate when the project includes electrical work and a choice of faceplates. The manufacturer lists both 120V and 240V configurations.
Keep in mind. The higher-output configuration needs the appropriate electrical installation. The quoted opening is for a specific trim configuration; the rear-width requirement is 23 5/16 inches.
Exact model
Ei29
Opening reference (W × H × D)
29⅝ × 20 5/16 × 11 13/16 in; 3- or 4-sided finishing trim only
Power
1,400W at 120V / 2,800W at 240V
Connection
120V plug-in or hardwire; 240V hardwire only
Finishing
Faceplate choice changes opening requirements
Before you commit: Request the exact faceplate, opening diagram and electrical configuration together, before buying.
Retailer quoteLog set; does not enclose the opening
A different approach if you want to keep the existing firebox visible. A log set sits inside the opening rather than filling it with a new enclosed front.
Keep in mind. The recommended opening in the manual is for the viewing effect. It should not be presented as a universal safety clearance or an automatic fit verdict.
Exact model
RLG25
Opening reference (W × H × D)
26 × 22 × 15 in; recommended for optimal viewing, not a minimum-fit rule
Power
120V, 1,500W
Connection
Plug-in; 15A circuit, dedicated preferred
Finishing
Existing firebox remains visible around the logs
Before you commit: Check the appearance in your firebox, the cord route and the manual’s installation requirements.
Separate the appliance, trim or faceplate, delivery, electrical work, preparation of the old fireplace and finishing repairs. For an existing gas appliance, include the professional work needed to decommission it. For an old wood-burning fireplace, establish its condition and how the remaining chimney will be handled.
The $769 Napoleon figure is a manufacturer starting base price checked on September 26, 2026. It is not an installed price or a promise of the lowest retail offer. Ask other dealers to quote the exact model and accessory combination, rather than a similarly named series.
Heat output is not a room-size guarantee
Actual comfort depends on insulation, outside temperature, ceiling height, air movement and the room’s heat loss. Use an electric insert as supplemental heat unless the complete heating design establishes otherwise. We do not rank products using manufacturer room-coverage claims.
Regency lists a higher-powered 240V configuration for Ei29. That option needs the appropriate electrical installation; it is not something to assume from the appearance of the fireplace or an existing outlet.
Estimate electricity cost
Illustrative starting values: a 1,500W heater running continuously for four hours at $0.30/kWh. Enter your model’s rated wattage and your electricity rate.
$1.80 per day
$54.00 for 30 days at this usage. Formula: watts ÷ 1,000 × hours × $/kWh. Thermostat cycling can reduce actual use. Flame-only consumption varies and is not assumed to be zero.
Replacing wood or gas: plan the work around the insert
Existing wood-burning fireplace
Have the condition of the fireplace and chimney assessed and establish how the old system will be left safe and weather-resistant. Check the selected product’s instructions for preparation, ventilation and installation in that type of opening. An electric unit does not repair damaged masonry.
A nearby outlet is useful only if its circuit, grounding and location meet the appliance requirements. Confirm where the plug and cord will sit without obstructing the appliance.
Existing gas fireplace
Have a qualified professional handle gas disconnection and any required capping, removal or decommissioning. Do not assume an electric insert can be put inside an active gas appliance. Establish the approved replacement arrangement with the installer before ordering.
Hardwiring and circuit changes also need qualified electrical work. Follow the model manual for power supply and clearances. The Napoleon and Redstone manuals specify dedicated circuits; Dimplex’s RLG25 manual describes a dedicated circuit as preferred.
Can you show this exact model with the room lights on and the heater running?
Which trim or faceplate is included, and how much of the old opening will remain visible?
Does the opening meet the full manual, including its rear shape and clearances?
What electrical work is included in the installation quote?
Who supplies replacement parts and handles warranty labor locally?
What are the return terms if the unit or selected trim does not fit?
Flame appearance and fan noise are worth evaluating in person. Marketing images can show optional accessories, carefully controlled lighting and a different room scale from yours.
What this comparison is based on
We used US manufacturer product pages, owner’s manuals and specification sheets, checked September 26, 2026. Models were selected for documented existing-opening use and clear model identification. A log set is included as a separate product type. The list is a research shortlist, not an exhaustive market survey.
We have not measured heat output, sound levels or flame realism. We do not assign star ratings or use customer reviews as our own test results. Missing comparable prices remain dealer or retailer quotes. Where a general product page conflicts with a model-specific manual, the entry explains which source we use.
First published September 26, 2026. Confirm the current manual supplied with the appliance, exact SKU, included accessories, availability and warranty before purchase. Source links are provided with every model.
Common questions about electric inserts
Can I put an electric insert in an existing fireplace?
Potentially, if the chosen model is approved for that installation and the opening, power supply and preparation meet its manual. Measure the full cavity and have the existing wood or gas system assessed before ordering.
Is a 26-inch insert exactly 26 inches wide?
The name may refer to a nominal size or an outer dimension. The cavity, trim and viewing window can have different measurements. Use the exact SKU and its opening diagram, not the size in the product title alone.
What is the difference between an insert and an electric log set?
An enclosed firebox provides a new appliance front, often with a trim or faceplate. An open log set sits inside the existing firebox and leaves more of its interior visible.
Can these fireplaces plug into a regular outlet?
Some support plug-in installation, but the outlet, circuit and location must meet the specific manual. Other configurations use hardwiring. A 240V configuration requires the appropriate supply and installation.
How much does an electric insert cost to run?
Multiply kilowatts by hours and your electricity rate. At 1,500W, four continuous hours and $0.30/kWh, the illustrative cost is $1.80 per day. Actual use changes with heater cycling and settings.
Which electric insert has the most realistic flame?
This research does not establish a realism winner. Compare the exact models in person, in ordinary room lighting, and check whether the display uses the same media and accessories you plan to buy.
Can I convert an existing gas fireplace myself?
Gas decommissioning and electrical changes should be handled by qualified professionals. Confirm that the intended replacement is permitted by the selected appliance’s instructions and local requirements.
Plan the fireplace around the room
Once the model and opening work together, plan the surround, hearth and nearby built-ins. For a broader renovation, see our fireplace planning and remodeling-cost resources. Service availability depends on location.
