Electric Fireplace Insert for Existing Fireplace
Transform your outdated or unused fireplace into a beautiful, efficient, and low-maintenance focal point. This complete guide covers everything you need to know about choosing, sizing, and installing an electric insert for your existing masonry or prefab fireplace.
Start Learningđź“‹ What You'll Learn
Give Your Old Fireplace a New Purpose
If you have an existing wood-burning fireplace that is inefficient, messy, or simply unused, an electric fireplace insert is one of the most practical and cost-effective upgrades you can make. Unlike gas or wood inserts, electric models require no venting, no chimney liner, and no complex installation. They slide into your existing firebox, plug into a standard outlet, and instantly provide ambiance and supplemental heat.
This guide will walk you through every consideration, from measuring your firebox to understanding BTU output, so you can make a confident purchase. Whether you are looking for a compact insert for a small space or a top-tier model with realistic flames, we have you covered.
Why an Electric Insert Makes Sense for Your Existing Fireplace
Converting a traditional fireplace to electric is a popular choice for homeowners who want the look of a fire without the drawbacks of wood or gas. Here are the key advantages:
- Zero venting required: No chimney, flue, or gas line needed. This means you can use your existing fireplace even if the chimney is damaged or unlined.
- Plug-and-play installation: Most models run on a standard 120V household outlet, making them ideal for DIY-friendly projects.
- Clean and low-maintenance: No ash, soot, or creosote. Cleaning is as simple as dusting and occasionally wiping the glass — see our electric fireplace cleaning guide.
- Flexible heating: Use the flame effect with or without heat. Many models include thermostats and remote controls for precise comfort.
- Safe and efficient: Electric inserts produce no carbon monoxide and are considered one of the safest fireplace options. Learn more in our electric fireplace safety tips.
đź’ˇ Cost consideration: While electric inserts are generally more affordable to install than gas or wood inserts, running costs depend on your electricity rates. For a detailed breakdown, see electric vs gas running costs.
Types of Electric Fireplace Inserts
Electric inserts are not one-size-fits-all. Understanding the different types will help you choose the right model for your existing fireplace.
1. Standard Electric Inserts
These are designed to fit into a masonry or prefab firebox. They typically feature a realistic flame effect, a heater (often 1,500W), and a remote control. Many are equipped with a blower to distribute heat more effectively.
2. Electric Log Sets
If you prefer a more open look, an electric log set sits inside your existing firebox on a grate. It provides the illusion of burning logs without the heat output of a full insert, though some models include a small heater.
3. Infrared vs. Fan-Forced
Most electric inserts use either fan-forced or infrared heating. Fan-forced models are common and budget-friendly, while infrared models tend to be quieter and more efficient at heating people and objects directly. Our infrared vs fan-forced comparison explains the differences in detail.
4. Built-in vs. Freestanding
For an existing fireplace, you will want a built-in (insert) model. Freestanding units are designed to sit on the floor or a stand and are not meant to slide into a firebox. If you are considering a freestanding unit, see our guide to freestanding electric fireplaces with blowers.
Sizing Your Electric Insert: A Step-by-Step Guide
The most critical step is ensuring the insert fits your existing fireplace opening. Electric inserts are available in a range of sizes, from compact 18-inch models to large 60-inch units. Here is how to measure correctly:
- Measure the firebox opening: Record the width, height, and depth in inches. Be precise — measure at the narrowest point.
- Account for clearance: You need at least 1–2 inches of clearance on all sides for ventilation and to avoid scratching the surround.
- Check the hearth depth: If your hearth is shallow, a slim insert (under 10 inches deep) may be necessary.
- Consider the viewing area: A larger viewing area gives a more dramatic flame effect. For small fireboxes, look for electric inserts for small spaces.
For a more detailed sizing worksheet, see our fireplace sizing guide. If you are unsure about your fireplace type, our article on electric inserts for wood-burning fireplaces covers common scenarios.
Heating Capacity and BTU: What to Expect
Electric fireplace inserts are generally used for zone heating or supplemental heat. Their heating capacity is measured in British Thermal Units (BTUs). Most residential electric inserts produce between 4,000 and 5,100 BTUs, which is enough to heat a room up to about 400 square feet.
If you need to heat a larger area, you may need a more powerful unit or a different heating solution. Our electric fireplace BTU guide provides a full breakdown. You can also use a fireplace BTU calculator to determine your room's specific needs.
đź“Ź Quick rule of thumb: For a room up to 400 sq. ft., a standard 1,500W electric insert (about 5,100 BTUs) is usually sufficient. For larger spaces, consider a high-output electric fireplace or a secondary heat source.
Installation: What to Expect
One of the biggest advantages of electric inserts is their straightforward installation. In most cases, you can install an electric insert yourself in under an hour. Here is the general process:
- Unbox and inspect the insert and all included hardware.
- Prepare the firebox: Remove any old logs, grates, or ash. Clean the firebox thoroughly.
- Slide the insert into place. Ensure it is level and that the trim overlaps the fireplace opening.
- Secure the insert if required by the manufacturer (some models include brackets).
- Plug in the unit to a nearby outlet. If no outlet is available, you may need an extension cord or an electrician to add one.
- Test the flame and heater before finishing.
For a more detailed walkthrough, see our plug-and-play installation guide. If you are converting from wood, our article on converting a wood-burning fireplace to electric offers additional tips.
Efficiency and Running Costs
Electric inserts are 100% efficient at the point of use, meaning all the electricity consumed is converted into heat. However, the cost to run one depends on your local electricity rates and how often you use the heater.
Generally, using an electric insert for a few hours a day adds a modest amount to your monthly bill. If you are concerned about energy usage, look for models with a thermostat and timer. Our guides on are electric fireplaces expensive to run and fireplace electricity usage provide detailed cost analyses.
Compared to gas inserts, electric models often have a lower upfront cost but may cost more per hour to operate. See our electric vs gas running costs comparison for a full breakdown.
Safety First
Electric inserts are among the safest fireplace options available. They produce no open flame, no carbon monoxide, and no creosote. However, basic precautions still apply:
- Keep flammable materials (curtains, furniture) at least 3 feet away from the unit.
- Do not use an extension cord unless it is rated for the amperage of the insert.
- Ensure the insert is on a stable, level surface.
- Regularly inspect the cord and plug for damage.
- If you have children or pets, consider a model with cool-touch glass or a safety screen.
For more, read our comprehensive fireplace safety guide and electric fireplace safety tips.
Frequently Asked Questions
Can I put an electric insert in a wood-burning fireplace?
Yes. Electric inserts are specifically designed to fit into existing wood-burning fireboxes. You do not need to remove the chimney or make structural changes. See our guide on electric inserts for wood-burning fireplaces.
Do electric fireplace inserts need a chimney?
No. Electric inserts are ventless and do not require a chimney or flue. This makes them a great option for homes without a functional chimney. Learn more in our do fireplaces need a chimney article.
How much heat does an electric insert produce?
Most models produce around 5,000 BTUs, enough to heat a room up to 400 square feet. For larger rooms, consider a high-capacity model.
Can I use an electric insert as my primary heat source?
Electric inserts are typically used for supplemental or zone heating. While they can take the chill off a room, they are not designed to replace a central heating system. For whole-home heating, see can a fireplace heat an entire house.
Are electric inserts realistic looking?
Modern electric inserts offer remarkably realistic flames, with options like LED flame effects, crackling sounds, and faux logs. For the most realistic experience, look for models with crackling sound and high-definition flame technology.
What size electric insert do I need?
Measure your firebox opening (width, height, depth) and choose an insert that fits with at least 1–2 inches of clearance. For detailed guidance, see our fireplace sizing guide.
Final Thoughts
An electric fireplace insert is a smart, low-commitment way to breathe new life into an existing fireplace. It offers the charm of a real fire without the mess, maintenance, or venting hassles. By understanding your firebox dimensions, heating needs, and the available features, you can choose an insert that enhances both the comfort and aesthetics of your home.
Ready to explore specific models? Check out our best electric fireplace inserts for existing fireplaces or browse our full electric insert collection.
