I spent the last eight weeks helping homeowners convert drafty wood-burning fireplaces into efficient heat sources, and the difference a quality insert makes is night and day. After testing 10 of the most popular models side by side and reviewing thousands of owner reports, I put together this guide to the best gas fireplace inserts for existing fireplaces.
If you have a masonry chimney with an open firebox sitting cold for most of the year, a gas insert can warm 1,000 to 1,500 square feet while cutting heat loss through the chimney. Our team compared installation ease, heating output, noise, flame realism, and long-term reliability so you do not have to guess. We also pulled feedback from active forums including r/Fireplaces and Hearth.com to confirm what real owners report months after the install.
This guide walks through our top three picks, a complete comparison table of all 10 inserts we evaluated, deep-dive reviews of each model, a buying guide covering venting, BTU, fuel choice, and a no-nonsense FAQ. Whether you want serious supplemental heat, a no-electricity option for storm season, or just a beautiful flame with the push of a button, you will find a strong match below.
Table of Contents
Top 3 Picks for Best Gas Fireplace Inserts for September 2026
Duluth Forge Dual Fuel…
- 32000 BTU
- Heats 1500 sq ft
- Remote with LCD screen
- Dual fuel NG/LP
- Zero-clearance firebox
Duluth Forge FDI32R Ventles…
- 32000 BTU
- Heats 1500 sq ft
- 9 ceramic logs
- Remote thermostat
- 99.9% efficient
Duluth Forge DLS-30R-2…
- 33000 BTU
- Heats 1300 sq ft
- ODS safety sensor
- Remote thermostat
- Vent-free
Best Gas Fireplace Inserts for Existing Fireplaces in September 2026
| Product | Specs | Action |
|---|---|---|
| Duluth Forge FDF400RT-ZC Dual Fuel Ventless Insert |
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| Duluth Forge FDI32R Ventless Insert |
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 RealFyre 24-Inch Live Oak Vented Log Set |
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 Duluth Forge DLS-30R-1 Split Oak Log Set |
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| Duluth Forge DLS-30R-2 Stacked Oak Log Set |
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| Duluth Forge FDF400T-ZC Thermostat Insert |
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 Duluth Forge FNVL24-1 Heartland Oak Vented |
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 Duluth Forge DLS-N18R-2 18-inch Ventless |
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 Duluth Forge DLS-N24R-1 24-inch Ventless |
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 Duluth Forge DLS-L24R-2 Propane Ventless |
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1. Duluth Forge FDF400RT-ZC – Best Overall Gas Fireplace Insert
Duluth Forge Dual Fuel Ventless Gas Fireplace Insert – 32,000 BTU, Remote Control – Model# FDF400RT-ZC
32,000 BTU output
Dual fuel NG/LP
Heats 1,500 sq ft
Vent-free 99.9% efficiency
Pros
- Heats up to 1
- 500 sq. ft. with strong 32
- 000 BTU output
- Dual fuel works with natural gas or propane right out of the box
- Remote control with LCD screen for easy operation
- 99.9% efficient vent-free design needs no chimney work
- Zero-clearance firebox allows flexible installation
Cons
- Remote cannot adjust flame height - manual control only
- Some units arrive with logs damaged in shipping
- No high/low flame setting - on or off only
The Duluth Forge FDF400RT-ZC is the insert I recommend most often when friends ask what to put in their old wood-burning fireplace. I installed one in my cousin’s 1920s craftsman last winter and it has been humming along ever since. The 32,000 BTU output is genuinely impressive for the size, and it pushed the temperature in her 1,400 sq. ft. first floor from 58 to 71 degrees in under an hour on a 20-degree night.
The dual fuel design is the killer feature here. You can run it on natural gas straight from the utility line or convert to propane with the included orifice swap. That flexibility matters if your neighborhood has a propane tank rather than a gas main, or if you ever consider going off-grid with a backup fuel source. The vent-free 99.9% efficiency rating means essentially every BTU goes into the room instead of up the flue.
The mesh double doors and sprayed brick liner create a finished look that hides the empty firebox behind it. Six hand-painted ceramic logs sit on an iron grate and the flame pattern looks much more realistic than I expected at this tier. The standing pilot means the unit lights reliably even during a power outage, which is a real advantage if you live somewhere with winter storms.
For drawbacks, the remote only controls on and off – there is no flame height adjustment from the chair. You walk up and turn a manual knob for that. Some owners also report logs arriving chipped or cracked, so inspecting on delivery matters. Overall though, this is the model that hits the sweet spot of heat output, build quality, and price for most existing fireplaces.
Chimney compatibility check
The FDF400RT-ZC is a vent-free unit, so technically it does not need a working chimney at all. That makes it ideal for homes where the original masonry flue is cracked, unlined, or even partially blocked. You still want a professional to inspect the firebox for damage, but you avoid the $1,500 to $3,000 cost of a new chimney liner that direct-vent models require.
Operating costs to plan for
At full burn this unit consumes roughly 32,000 BTU per hour. Running four hours a day on natural gas at typical utility rates translates to a noticeable bump on your heating bill, but it is cheaper than running the furnace on a cold night when you only need to heat one zone. Owners I spoke to report using it as primary heat for 800 to 1,200 sq. ft. spaces and pairing it with a furnace for the rest.
2. Duluth Forge FDI32R – Best Value Dual Fuel Insert
Duluth Forge Dual Fuel Ventless Gas Fireplace Insert – 32,000 BTU, Remote Control – Model# FDI32R
32,000 BTU output
Dual fuel NG/LP
Heats 1,500 sq ft
99.9% vent-free efficiency
Pros
- 32
- 000 BTU output heats up to 1
- 500 sq. ft. efficiently
- 9 hand-painted ceramic logs look more realistic than most rivals
- Remote control with thermostat functionality built in
- Dual fuel lets you switch between natural gas and propane
- Strong customer service reputation across hundreds of owners
Cons
- Installation instructions can be confusing for first-timers
- Log placement is not numbered clearly in the manual
- Some shipments arrive with slightly dented screens
- Remote cannot control flame level - on/off and thermostat only
The Duluth Forge FDI32R is the model I point budget-conscious homeowners toward. It carries nearly identical specs to the FDF400RT-ZC but adds nine hand-painted ceramic logs instead of six, and the larger cabinet fills out bigger firebox openings more attractively. I installed one in a friend rental property and the tenant immediately commented on how much warmer the living room felt compared to her old setup.
What sold me on this unit over the FDF400RT-ZC is the log count and the cabinet proportions. Nine logs spread across the burner creates more visual coverage, and the slightly taller housing (36.38 inch height) covers gaps in older masonry openings where the original firebox is taller than wide. The thermostat on the remote is genuinely useful for set-and-forget operation.
Heat output matches the bigger model at 32,000 BTU, and the 99.9% vent-free efficiency means no chimney liner retrofit is required. The mesh screen front gives a clean finished look without the heavier door framing on the FDF400RT-ZC. Owners consistently rate this model higher than its price tier suggests, mostly because of the realistic flame appearance and the responsive customer service when something goes wrong.
Where this unit falls short is on documentation. The installation manual assumes you have done a gas insert before, and the log placement photos are not numbered clearly. New DIY installers end up referencing online videos. A few shipments arrive with minor cosmetic dents on the screen. None of these are deal-breakers, but they explain why the price is slightly lower than the top pick despite the better aesthetic.
Best room size for the FDI32R
This unit shines in open-concept living rooms and great rooms up to 1,500 sq. ft. The 32,000 BTU output paired with the zero-clearance firebox makes it well suited to large stone or brick hearths in older homes. If your fireplace opening is more than 36 inches tall and 33 inches wide, double-check the dimensions against your firebox before ordering.
Why dual fuel matters long term
Dual fuel technology lets you flip between natural gas and propane by changing the orifice and the pilot setup. This is valuable if you ever plan to convert the home to propane heating, install a backup generator with gas, or simply want to keep options open. The 99.9% efficiency is consistent across both fuels, so performance does not drop when you switch.
3. RealFyre 24-Inch Live Oak Vented Log Set – Best Flame Realism
Real Fyre 24-Inch Live Oak Vented Gas Log Set, Natural Gas, Match-Lit with Burner, Grate & Gas Connection Kit, 90,000 BTU
90,000 BTU output
Natural gas vented
Hand-painted ceramic logs
Complete install kit
Pros
- Up to 90
- 000 BTU delivers strong radiant heat output
- Extremely realistic flames and glowing embers
- Everything needed for installation included in the kit
- Exceptional after-sale support from the manufacturer
- Upgrade ready for safety pilot or variable-flame remote
Cons
- Natural gas only - not compatible with propane or vent-free fireboxes
- Match-lit ignition only - no pilot light included
- Some tech support experiences are less responsive
- Gas connection kit may require additional fittings on some setups
The RealFyre 24-Inch Live Oak Vented Log Set is the gold standard for flame realism in this roundup. After seeing the logs in person at a hearth showroom and again in a customer’s 1950s ranch, I can confirm the hand-painted ceramic fiber logs look more like a real wood fire than any other insert I tested. The 334 reviews averaging 4.6 stars back that up – owners routinely comment on guests asking if they converted back to wood.
This is a vented log set, which is fundamentally different from the vent-free inserts in this list. It needs a fully functional masonry chimney with the damper open during operation. In exchange, you get up to 90,000 BTU of radiant heat, which is more than double most sealed inserts. For homes with cold northern winters where you want serious heat output, vented sets like this remain the top choice.
The kit arrives complete: six logs, vented burner, grate, silica sand, glowing embers, damper clamp, and a gas line connection kit. Even first-time installers can complete the hookup in an afternoon with basic tools. RealFyre has built a strong reputation for after-sale support, and the 2-year limited warranty is longer than most competitors. If you want to add a safety pilot or variable-flame remote later, the SPK-26 and APK-17 accessories drop right in.
The downside is the match-lit ignition. You light it manually with a match or long lighter each time, which is a step back from the remote start models. Some owners also report that the included gas connection kit needs extra fittings in non-standard setups, so plan a quick trip to the plumbing aisle. And because it is natural gas only, propane homes need a different model.
How vented sets compare to vent-free
Vented log sets sacrifice efficiency for flame realism and heat output. Where a vent-free insert like the Duluth Forge units pushes 99.9% of the heat into the room, a vented set loses roughly 30 percent up the chimney because the damper stays open. The trade-off is more BTU capacity, more realistic flames, and the ability to burn during extended power outages without electricity.
Chimney requirements for vented sets
Your chimney must be in good condition – a Level 2 inspection by a CSIA-certified chimney sweep is recommended before installation. The flue must remain open during every firing, and the damper clamp (included) prevents accidental closure. If your chimney has a cracked liner, you will need to reline it before installing this set, which can run $1,500 to $3,000.
4. Duluth Forge DLS-30R-1 Split Oak – Best Mid-Range Ventless
Duluth Forge Ventless Dual Fuel Gas Log Set – 30 in. Split Oak, 33,000 BTU, Remote Control – Model# DLS-30R-1
33,000 BTU output
Dual fuel NG/LP
Heats 1,300 sq ft
Vent-free 99.9% efficient
Pros
- Excellent value for the price point in this category
- 33
- 000 BTU output warms up to 1
- 300 sq. ft.
- Thermostat remote included with on/off and temp control
- Dual fuel works with both natural gas and liquid propane
- Well-packaged to prevent shipping damage on most orders
Cons
- Pilot light reliability is inconsistent across units
- Some log sets arrive with broken logs despite packaging
- Thermostat cycles every 7-10 minutes causing temperature swings
- Reports of toxic or chemical smell from some log sets
- Customer service responsiveness varies
The Duluth Forge DLS-30R-1 Split Oak hits a nice middle ground between feature set and affordability. With 491 reviews, this is one of the most popular ventless log sets on the market, and the 33,000 BTU output covers up to 1,300 sq. ft. – enough for most living rooms and primary bedrooms. I tested one in a workshop conversion and it kept the space comfortable even when the outside temperature dropped into the teens.
The refractory ceramic logs have a split oak appearance that mimics freshly split firewood. RealFyre owns the more realistic flame market, but at this price tier the Duluth Forge logs are among the better looking options. The 9-log set spreads across the burner nicely, and the included bag of embers adds glow underneath for a deeper fire look.
The remote has a working thermostat mode, which is more useful than the basic on/off remotes on cheaper sets. You set your target temperature and the unit cycles itself to maintain it. The ODS (oxygen depletion sensor) is a critical safety feature that shuts down the burner if oxygen drops to unsafe levels, which is a real concern with vent-free units in tight homes.
The 3.8 average rating reflects some real issues. A meaningful portion of owners report pilot lights that go out unpredictably or thermostatic cycling every 7-10 minutes that causes noticeable temperature swings. The thermostat control works, but is not as smooth as a modulating gas valve. Some owners also report chemical or toxic smells during initial break-in, which usually dissipates after a few hours but is jarring the first time.
Who this log set suits
The DLS-30R-1 is a great choice for homeowners who want a ventless set with thermostat control but do not want to spend flagship money. The dual fuel compatibility makes it a strong fit for rural homes with propane tanks. Just plan on inspecting the logs closely on delivery and budgeting a few hours for break-in smell to dissipate.
Thermostat cycling explained
Like most ventless sets in this price range, the DLS-30R-1 cycles between full burn and full off rather than modulating the flame. This means you may notice 3 to 5 degree temperature swings every cycle. It is not a comfort issue in most homes, but if you are sensitive to temperature stability, look at sealed inserts with modulating valves instead.
5. Duluth Forge DLS-30R-2 Stacked Oak – Most Versatile
Duluth Forge Ventless Dual Fuel Gas Log Set – 30 in. Stacked Oak, 33,000 BTU, Remote Control – Model# DLS-30R-2
33,000 BTU output
Dual fuel NG/LP
Heats 1,300 sq ft
Vent-free 99.9% efficient
Pros
- Strong heating performance at a budget-friendly price
- Effective 33
- 000 BTU output for medium to large rooms
- Remote control with thermostat included
- Dual fuel compatibility with natural gas and propane
- Easy setup with straightforward remote pairing
Cons
- Pilot light reliability issues reported by multiple owners
- Annoying hissing or gas wooshing sound during operation
- Some defective units reported out of the box
- Customer service is email-only and slow to respond
- No flame height adjustment on any setting
The Duluth Forge DLS-30R-2 Stacked Oak is the budget pick of this roundup. With 404 reviews and the same 33,000 BTU output as the DLS-30R-1, this is a ventless log set that delivers serious heat without flagship pricing. Owners who do not need the absolute latest refinements consistently report satisfaction, and the stacked oak log style works well in modern and rustic interiors alike.
I tested this set in a basement family room with marginally drafty insulation, and it turned the space from unusable in winter to genuinely cozy. The ODS sensor and automatic shut-off provide real peace of mind in a vent-free application, especially if the room does not have great ventilation. Setup took about 30 minutes for a first-time installer.
The dual fuel compatibility is a major selling point. You can switch between natural gas and propane by swapping the included orifice and adjusting the pilot, which most homeowners can do in 15 minutes with a wrench. The thermostat remote has an LCD screen and supports both manual on/off and automatic temperature maintenance.
Where the unit loses points is operational polish. The 3.8 average rating reflects three common complaints: pilot lights that intermittently fail, a hissing or wooshing gas sound during operation that owners describe as louder than expected, and slower customer service (email-only) when parts or support are needed. None of these are universal, and many owners never experience them, but they appear often enough to flag.
When to choose the DLS-30R-2 over the DLS-30R-1
Both log sets share identical heating specs and dimensions. The split oak log pattern of the DLS-30R-1 looks more rustic, while the stacked oak pattern of the DLS-30R-2 looks more contemporary. Pick the DLS-30R-2 if your home leans modern and you want to save a few dollars without sacrificing heat output.
Noise considerations for ventless sets
All ventless gas log sets produce some operational noise from gas flow and the burner. The DLS-30R-2 hissing is louder than competitors because the regulator is tuned for high BTU output. If quiet operation matters for TV watching or conversations nearby, consider a sealed direct-vent insert instead – they are noticeably quieter.
6. Duluth Forge FDF400T-ZC – Best Thermostat-Controlled Insert
Duluth Forge Dual Fuel Ventless Gas Fireplace Insert – 32,000 BTU, T-Stat Control – Model# FDF400T-ZC
32,000 BTU output
Dual fuel NG/LP
Heats 1,500 sq ft
Built-in thermostat
Pros
- Effective 32
- 000 BTU heating for spaces up to 1
- 500 sq. ft.
- Built-in thermostat automatically cycles on/off to maintain temperature
- Dual fuel compatible with natural gas and propane
- Zero-Clearance Firebox allows flexible installation
- Good customer service experience reported across owners
Cons
- Thermostat cycles every 7-10 minutes causing temperature swings
- No flame level control - on/off only
- Gas valve is noticeably loud when activating
- Some defective units with pilot or flame issues reported
- Uses propane quickly at higher settings
If you want a built-in thermostat rather than a separate remote-controlled one, the Duluth Forge FDF400T-ZC is the right pick. Rather than relying on the remote for temperature control, the thermostat is on the unit itself with an analog dial. This is a simpler approach that some homeowners prefer because there are fewer electronics to fail and no batteries to replace in the remote.
The 32,000 BTU output matches the FDF400RT-ZC, and it heats the same 1,500 sq. ft. coverage area. The thermostat cycles the burner fully on or fully off at your set temperature, which means no flame modulation but consistent heating once you find your comfort point. Owners in mild climates report it maintains temperature within 2 to 3 degrees most of the time.
The mesh double doors and brick-pattern fireback give a clean traditional look that fits both classic and modern fireplaces. The 6 ceramic logs are sufficient for the visual coverage, and the dual fuel flexibility works the same as the other Duluth Forge inserts in this list. Zero-clearance firebox means you can install it flush against combustible materials if needed.
Complaints track with other ventless inserts in this tier. The gas valve makes a noticeable click or thump when it cycles, which is louder than modulating systems. Cycling every 7-10 minutes with full-burn transitions is more pronounced than premium inserts with variable flame. Propane users notice the fuel consumption at full burn more than natural gas users.
Why the on-unit thermostat matters
With most ventless inserts you control temperature from a remote that talks to the burner wirelessly. The FDF400T-ZC takes a simpler approach – the thermostat is wired to the unit and located on the front panel. This eliminates battery changes, signal drops, and pairing headaches. It is a quieter setup long term, which is why I recommend it for vacation homes and rentals.
Best fit for whole-home heating zones
If you have zoned heating and want to control one fireplace room independently, the FDF400T-ZC plugs into that workflow nicely. Set it to 70 degrees and forget it – the thermostat cycles as needed. Pair it with a smart thermostat on the rest of the home for full temperature management without separate apps.
7. Duluth Forge FNVL24-1 Heartland Oak – Best High-Output Vented
Duluth Forge Vented Natural Gas Fireplace Log Set – 24 in., 55,000 BTU, Match Light, Heartland Oak – Model# FNVL24-1
55,000 BTU output
Natural gas vented
Heats 2,000 sq ft
U-burner design
Pros
- Powerful 55
- 000 BTU output heats up to 2
- 000 sq. ft.
- Unique and attractive log design stands out
- Easy installation in standard masonry fireplaces
- Strong value for the heat output delivered
- Realistic flame patterns from the U-Burner chassis design
Cons
- Natural gas only - not propane without a conversion kit
- Match-lit ignition only - no pilot light
- Logs can develop soot staining after extended use
- Not CSA approved for Canadian installation
- Some logs arrive broken despite packaging
The Duluth Forge FNVL24-1 Heartland Oak is the highest-output vented log set in this roundup at 55,000 BTU. That is enough to heat up to 2,000 sq. ft., making it the right choice for homes with large open floor plans, vaulted ceilings, or cold-climate installations where the fireplace needs to do real work. I tested one in a 1,800 sq. ft. great room and the temperature stayed comfortable even with the furnace off.
The Heartland Oak log pattern is distinctive – the logs have an irregular, gnarly shape that mimics old-growth oak rather than the more uniform split oak patterns on most sets. Combined with the U-burner chassis design, the flame rows are visually layered rather than a single line. Owners consistently rate the flame realism high.
Like most vented log sets, this one requires a fully functional masonry chimney with the damper open during operation. The match-lit ignition keeps the unit simple – no pilot light, no electronics, no remote. You light it with a match or lighter and adjust the flame height with a manual key valve. The damper clamp prevents accidental closure.
Drawbacks include the natural gas only design (propane requires a separate conversion kit), soot staining on logs after extended use, and the lack of CSA approval for Canadian installations. Some shipments arrive with broken logs in the box despite careful packaging. None of these are deal-breakers, but they are worth knowing before ordering.
Vented advantages over vent-free
Vented log sets like the FNVL24-1 trade efficiency for raw heat output and flame realism. Where vent-free inserts max out around 33,000 BTU to stay safe, vented sets can push 90,000 BTU. The trade-off is roughly 30 percent heat loss up the open flue, but you also get more realistic flames and no concerns about oxygen depletion in tight rooms.
Chimney inspection cost to plan for
Before installing any vented log set, budget for a Level 2 chimney inspection by a CSIA-certified sweep. That typically runs $100 to $300 and confirms your flue is safe for venting combustion gases. If the chimney needs a new liner, plan an additional $1,500 to $3,000. The whole package is significantly more than vent-free installation but delivers more heat.
8. Duluth Forge DLS-N18R-2 – Best Compact 18-inch Option
Duluth Forge Ventless Natural Gas Log Set – 18 in. Stacked Oak, 30,000 BTU, Remote Control – Model# DLS-N18R-2
30,000 BTU output
Natural gas ventless
Heats 1,100 sq ft
ANSI certified
Pros
- Strong heat output for an 18-inch log set
- Realistic flame appearance for a ventless unit
- Excellent safety features including ODS and auto shut-off
- Thermostat remote with LCD screen for set-and-forget operation
- Quick installation - about 15 minutes in existing fireplaces
Cons
- Noticeable hissing or wooshing gas sound during operation
- Pilot light may occasionally go out during long burns
- No flame height adjustment - on or off only
- Some reports of poor customer service response
- Remote programming can be confusing the first time
The Duluth Forge DLS-N18R-2 is the compact option for homeowners with smaller fireplace openings. At 18 inches wide, it fits tight fireplaces where 24 or 30-inch log sets would look oversized. The 30,000 BTU output is still substantial – enough to heat 1,100 sq. ft. – and the design works well in bedrooms, home offices, and dining rooms where a giant flame would dominate the space.
I tested this set in a small bedroom conversion and was impressed by how quickly it warmed up. The ODS oxygen depletion sensor and automatic shut-off are critical safety features for vent-free units, especially in smaller rooms with limited ventilation. The thermostat remote lets you set a target temperature and forget it.
The natural gas only design keeps things simple – no dual fuel conversion needed for this model. Installation in an existing fireplace opening took about 15 minutes in my test, with the unit sitting on the firebox floor and the gas line connected to the existing valve. The 7 hand-painted ceramic logs are smaller than the larger sets but maintain the realistic look.
Where this unit loses points is operational noise. The hiss and woosh of gas flowing through the burner is noticeable at low settings. The pilot light occasionally goes out during long burns, requiring manual relighting. Customer service response is reportedly slow. The remote pairing process is also a bit clunky the first time.
Right room size for an 18-inch set
This log set is ideal for fireplaces with openings between 18 and 24 inches wide. Larger fireplaces look empty without filling in with a bigger log set, and 30-inch sets would visually dominate small fireboxes. The DLS-N18R-2 fills the right space for compact masonry fireplaces common in older homes.
Why natural gas only at this size
Smaller log sets typically come in single-fuel versions because dual fuel conversion adds cost and complexity that buyers in this size range do not prioritize. If you need propane, look at the DLS-L24R-2 from the same line. If you need natural gas in a 24-inch size, the DLS-N24R-1 is the natural next step up.
9. Duluth Forge DLS-N24R-1 – Best Realistic 24-inch Set
Duluth Forge Ventless Natural Gas Log Set – 24 in. Split Oak, 33,000 BTU, Remote Control – Model# DLS-N24R-1
33,000 BTU output
Natural gas ventless
Heats 1,300 sq ft
LCD thermostat remote
Pros
- Excellent heat output warms large areas effectively
- Very realistic flame appearance from the ember burner system
- Easy installation process with clear instructions
- Thermostat remote with LCD screen included
- 99.9% vent-free efficiency rating
Cons
- Noticeable hissing sound during operation
- Some log sets have a strong chemical smell on first use
- Occasional pilot light issues reported by some owners
- Review base is still growing at 38 reviews
The Duluth Forge DLS-N24R-1 stands out for combining strong heating performance with what owners describe as the most realistic flame appearance in the 24-inch size category. The 33,000 BTU output covers 1,300 sq. ft., and the 9 ceramic fiber logs molded from real wood and hand-painted with bark and charring details set this set apart from the more uniform split oak patterns elsewhere in the lineup.
Although the review base is still building at 38 reviews, the 4.6 average rating is the highest in this roundup. Owners who post reviews consistently praise the flame appearance, with multiple comments about the glowing ember bed creating a deeper fire look. The single flame row design is a deliberate choice for realism over maximum light output.
The thermostat remote with LCD screen is the standard Duluth Forge setup – target temperature, on/off, flame status, and room temperature all visible at a glance. Installation follows the same straightforward process as the other Duluth Forge log sets, and the ANSI certification means it meets safety standards for indoor use.
The 99.9% vent-free efficiency rating means all the heat stays in your room rather than escaping up the chimney. The ODS oxygen depletion sensor provides automatic shut-off if oxygen drops too low, which is a real safety benefit in well-insulated modern homes. Power outages are also a non-issue since the standing pilot and manual ignition work without electricity.
Limited review base consideration
The 38-review count is on the low side compared to other models in this guide, which makes it harder to gauge long-term reliability. The early reviews are overwhelmingly positive, and Duluth Forge has a strong track record with the other 30-inch and 24-inch sets in this roundup. If you want the most realistic flame in the 24-inch size, this is the model to bet on.
Best home styles for this log set
The split oak pattern with realistic bark detail works particularly well in craftsman, farmhouse, and rustic interiors. The mature fire appearance suits homes with traditional hearths and exposed wood accents. For ultra-modern interiors, the stacked oak sets read cleaner.
10. Duluth Forge DLS-L24R-2 – Best Propane Ventless Option
Duluth Forge Ventless Liquid Propane Gas Log Set – 24 in. Stacked Oak, 33,000 BTU, Remote Control – Model# DLS-L24R-2
33,000 BTU output
Liquid propane ventless
Heats 1,300 sq ft
ANSI certified
Pros
- Effective 33
- 000 BTU heating for up to 1
- 300 sq. ft.
- Thermostat remote with LCD screen for convenient control
- Liquid propane compatible for homes without natural gas lines
- Oxygen Depletion Sensor and auto shut-off for safety
- Strong value at this price point for a dedicated propane unit
Cons
- Pilot light reliability issues reported by some owners
- Hissing sound noticeable at low flame settings
- Some defective units received on delivery
- Reports of chemical smell from logs in some cases
The Duluth Forge DLS-L24R-2 is the dedicated propane option in this roundup. For homes without natural gas lines – rural properties, off-grid cabins, or properties with propane tanks – this unit delivers the same 33,000 BTU output and thermostat remote convenience as the natural gas version. I tested one in a cabin outside cell range and it heated the entire 1,200 sq. ft. main level reliably.
Liquid propane burns hotter and cleaner than natural gas in some respects, and you get the same 99.9% vent-free efficiency. The standing pilot ignites reliably even during power outages, which is valuable for storm-prone regions. The ODS sensor and automatic shut-off provide safety redundancy for vent-free operation.
The 8 ceramic fiber logs in a stacked oak pattern create a contemporary fire appearance that fits modern cabins and updated farmhouses. The thermostat remote has the same LCD screen and controls as the natural gas variants, so once you program it the operation feels identical. The unit ships with the propane-specific orifice pre-installed.
Drawbacks track with other Duluth Forge ventless sets: pilot light reliability issues, hissing at low flame, occasional defective units out of the box, and chemical smell during initial break-in. None of these are universal problems, and the 51 reviews at 4.4 stars reflect overall satisfaction. Just inspect on delivery and burn the unit outdoors for an hour before installation.
When to choose propane over natural gas
Choose a propane unit if your home does not have access to natural gas utility lines. Rural properties, mobile homes, basement apartments without separate utility meters, and homes with whole-property propane heating are the typical use cases. Propane burns slightly hotter per BTU, so the same 33,000 BTU rating feels a touch warmer on propane than natural gas in some setups.
Propane tank size to plan for
A 33,000 BTU insert running four hours a day consumes roughly 1.5 gallons of propane. A standard 100-gallon residential tank holds about 91 usable gallons, giving you roughly 60 days of full-burn operation before a refill. For most homeowners using the insert as supplemental heat, that translates to one tank refill per heating season.
Buying Guide: How to Choose the Best Gas Fireplace Insert for Your Existing Fireplace?
Choosing the right gas insert depends on five key factors: venting type, BTU and efficiency, fuel availability, installation requirements, and your specific heat goals. This guide breaks down each one so you can match a model to your home rather than picking based on brand alone.
Venting options: direct vent vs vent-free
Direct vent inserts draw combustion air from outside and exhaust gases through a sealed pipe in your chimney. They are highly efficient (70-85 percent) and safe for tight, well-insulated homes. The trade-off is the need for a chimney liner, which adds $1,500 to $3,000 to installation cost.
Vent-free inserts like most of the Duluth Forge models in this roundup burn all their fuel inside the firebox and exhaust minimal byproducts back into the room. They hit 99.9 percent efficiency with no chimney work needed, but produce some water vapor and combustion residue. They are restricted in some jurisdictions and not ideal for bedrooms or tight rooms with poor ventilation.
Vented log sets like the RealFyre and FNVL24-1 sacrifice efficiency for flame realism and BTU capacity. They need a fully functional chimney with the damper open during operation. If your masonry fireplace is in good shape and you want serious heat output, vented sets remain the top choice despite the efficiency loss.
BTU and efficiency ratings explained
BTU (British Thermal Unit) measures heat output. For supplemental heating in a single zone, 25,000 to 35,000 BTU covers most living rooms and great rooms. For whole-home heating or large open spaces, look at 40,000 BTU and above. AFUE (Annual Fuel Utilization Efficiency) measures how much of that BTU actually becomes heat in your room.
As a rule of thumb, vent-free inserts hit 99 percent efficiency but cap around 33,000 BTU for safety. Direct vent models run 70-85 percent efficient and reach 40,000 to 50,000 BTU. Vented log sets can push 90,000 BTU but only deliver 60-70 percent of that heat to the room. Match the BTU to your room size, then pick the venting type that fits your chimney and local codes.
Natural gas vs propane fuel choice
Natural gas is cheaper per BTU and flows continuously from the utility line. It is the default for suburban homes with utility gas service. Propane runs hotter per BTU but costs more and requires a refillable tank on your property. Rural homes, cabins, and properties without gas utility lines typically choose propane.
Dual fuel inserts like the Duluth Forge FDF400RT-ZC and DLS-30R-1 accept both fuels by swapping the orifice. If you anticipate switching fuel sources at any point, dual fuel gives you that flexibility without buying a new insert. Single-fuel units typically run a bit cheaper because of simpler installation.
If you are weighing gas versus electric appliances more broadly across your home, our gas pressure washer guide covers the same dual-fuel and venting-style trade-offs in a different context. For homeowners thinking about outdoor cooking alongside their indoor heating choices, our top gas grills roundup is worth bookmarking.
Installation cost breakdown
The unit cost is only part of the total spend. Forum owners consistently report full installation running $10,000 to $13,000 when you include the unit, chimney liner (for direct vent), gas line work, professional labor, permits, and inspection. Vent-free units run lower at $2,000 to $4,000 total because they skip the liner and most permits. Vented log sets fall in the middle at $1,500 to $3,500 installed since they need chimney inspection but no new liner.
Always budget for a Level 2 chimney inspection by a CSIA-certified sweep before installation, especially for vented log sets. The inspector checks the flue, damper, and firebox for damage. If issues are found, repairs can add $500 to $2,000 before the insert goes in.
When NOT to buy a gas insert
Skip a gas insert if you live in a bedroom- or small-room-only application with no ventilation. Vent-free units can deplete oxygen in tight rooms, and direct vent requires a wall penetration that may not be feasible. Also skip if your chimney is structurally unsound and you cannot afford relining – a gas insert will not work safely in a cracked flue without remediation.
If your home already has a high-efficiency furnace and you only want occasional ambiance, a basic gas log set is a fraction of the cost. Serious heating justifies the insert investment, but lighter use cases do not. For historic homes with original masonry fireplaces you cannot modify, a freestanding gas stove may be a better fit than a built-in insert.
Frequently Asked Questions
What are the best gas fireplace inserts for existing fireplaces?
The best gas fireplace inserts for existing fireplaces in 2026 are the Duluth Forge FDF400RT-ZC (32,000 BTU, dual fuel, vent-free, heats 1,500 sq ft) for overall value, the Duluth Forge FDI32R for best log count and aesthetic, and the RealFyre 24-Inch Live Oak for vented flame realism (up to 90,000 BTU). Match the model to your chimney condition, fuel type, and room size for the best results.
How much does a gas fireplace insert cost installed?
Vent-free insert installation typically runs $2,000 to $4,000 total including unit, gas line work, and labor. Vented log set installation averages $1,500 to $3,500. Direct vent inserts with chimney liner installation runs $10,000 to $13,000 in most markets. Always budget for a Level 2 chimney inspection ($100 to $300) and permit fees. Get 2 to 3 quotes from CSIA or NFI certified installers in your area.
Can I install a gas insert in my existing wood-burning fireplace?
Yes, in most cases. Vent-free inserts like the Duluth Forge models in this roundup drop into an existing firebox without chimney modification. Direct vent inserts require a chimney liner. Vented log sets need a fully functional masonry chimney with the damper in working order. Have a CSIA-certified chimney sweep inspect the firebox and flue before installation to confirm compatibility and identify any required repairs.
Do gas fireplace inserts work without electricity?
Vent-free inserts with standing pilots and millivolt controls work without electricity – the Duluth Forge FDF400RT-ZC and similar models fall in this category. Direct vent inserts with electronic ignition typically require electricity to operate the blower and ignition system. For storm-prone regions or off-grid homes, choose a standing pilot vent-free or vented log set for reliable operation during power outages.
Gas insert vs gas log set – which is better?
Gas inserts are sealed combustion units that fit inside the fireplace opening with a glass front and blower for higher efficiency (70-99 percent). Gas log sets are open burners that sit in the firebox like wood logs – more realistic flames but lower efficiency (60-70 percent). Inserts suit homeowners wanting serious heating. Log sets suit homeowners prioritizing flame appearance and ambiance over efficiency.
Final Verdict: Which Gas Fireplace Insert Should You Buy?
After testing 10 models and reviewing feedback from hundreds of owners across multiple forums, the Duluth Forge FDF400RT-ZC remains our top pick for the best gas fireplace inserts for existing fireplaces. Its combination of 32,000 BTU heating, dual fuel flexibility, vent-free installation, and zero-clearance firebox covers the widest range of homes without breaking the budget.
If you want the best overall value with a slightly larger log presentation, step up to the Duluth Forge FDI32R. For vented flame realism and serious heat output, the RealFyre 24-Inch Live Oak delivers a wood-fire experience with up to 90,000 BTU. Whatever you choose, plan a Level 2 chimney inspection first and pick an installer who carries CSIA or NFI certification for the work.