A gas fireplace insert drops into an existing fireplace opening and does the one thing a wood fire can’t: turn on with a switch.
No wood to split, no ash to shovel, no chimney fire risk from a decade of neglected creosote.
Just heat, on demand, at whatever setting you want.
That convenience is exactly why gas fireplaces have become the default choice for so many renovations, and why inserts specifically are popular — they retrofit into a fireplace you already have instead of requiring new construction.
The catch is that “gas fireplace insert” covers three genuinely different systems, and picking the wrong one for your house is an expensive mistake to walk back.
Direct vent, natural-vent, and ventless inserts all look similar in a showroom. They are not interchangeable.
We’ll get into exactly why below, along with five current inserts worth a look.
Direct Vent vs. Vented vs. Ventless: Pick the Right Category First
Before you fall in love with a specific model, figure out which of these three categories your house can actually support — this decision matters more than brand or price.
Direct vent inserts pull combustion air from outside through a sealed pipe and exhaust the byproducts the same way, so nothing from the fire actually enters your living space. That sealed design is why they’re considered the safest option and why building codes are generally most permissive about where you can install them. The tradeoff is installation: you need an exterior wall or a way to route venting outside, and that adds cost.
Natural-vent (“B-vent”) inserts use a standard vertical flue, similar to a traditional chimney, and burn gas logs that produce a realistic flame at the cost of some efficiency — more of the heat goes up the vent instead of into the room.
Ventless inserts burn gas cleanly enough that no venting is required at all, which makes them the cheapest and easiest to install. In exchange, they release combustion byproducts, including a small amount of carbon monoxide, directly into the room. Fairfax County Fire and Rescue’s guidance on ventless fireplace safety is worth reading in full before you buy one — the short version is: size the unit correctly for the room, run a working carbon monoxide detector in that room, and don’t run it unattended or all day. Some jurisdictions restrict or ban ventless units entirely, so check your local codes before you buy, not after.
If you’re still deciding between gas and an electric insert instead, that’s a genuinely different comparison worth reading separately — this guide assumes you’ve already settled on gas.
- For flexibility between fuel types: a dual-fuel insert with remote control runs on either natural gas or propane.
- For a natural gas line with thermostat control: a natural gas insert with thermostat control holds a set temperature instead of just on/off.
- For propane-only homes: a liquid propane insert with remote control is built specifically for propane, not adapted from a natural gas design.
- For retrofitting an existing masonry fireplace: a universal zero-clearance firebox insert is designed for that exact job.
The 5 Best Gas Fireplace Inserts Right Now
- VENTLESS DUAL FUEL TECHNOLOGY: Patented technology gives the option to fuel the Fireplace Insert with either Natural Gas or Liquid Propane; 32000 BTU Vent Free gas heater is 99.9% efficient; No outside duct or chimney is needed to heat up to 1500 sq. ft.
- VENTLESS DUAL FUEL TECHNOLOGY: Patented technology gives the option to fuel the Fireplace Insert with either Natural Gas or Liquid Propane; 32000 BTU Vent Free gas heater is 99.9% efficient; No outside duct or chimney is needed to heat up to 1500 sq. ft.
- CUSTOMIZABLE ZERO CLEARANCE DESIGN: Can be recessed into a wall or paired with a face mantel for a seamless, built-in look. Offers design flexibility to suit your home’s interior.
- CUSTOMIZABLE ZERO CLEARANCE DESIGN: Can be recessed into a wall or paired with a face mantel for a seamless, built-in look. Offers design flexibility to suit your home's interior
- ZERO CLEARANCE DESIGN: Easily installs flush into a wall or pairs with a mantel for a custom-built look. Ideal for maximizing floor space and clean aesthetics.
Gas Fireplace Insert Comparison
| Insert | Fuel | BTU | Control | Best For |
|---|---|---|---|---|
| Duluth Forge FDI32R | Dual (NG or LP) | 32,000 | Remote | Fuel flexibility |
| Duluth Forge FNF300T | Natural gas only | 26,000 | Thermostat | Set-and-hold temperature |
| Duluth Forge FLF300R | Liquid propane only | 26,000 | Remote | Propane-only homes |
| ProCom PC36VFC | Ventless, universal | Not stated | Not stated | Retrofitting an existing opening |
| Duluth Forge FDF400T-ZC | Dual (NG or LP) | 32,000 | Thermostat | Fuel flexibility, thermostat preferred |
“Not stated” means the seller’s current listing doesn’t specify that detail — check the listing directly before buying if it matters for your use.
1. Duluth Forge Dual Fuel Ventless Insert (FDI32R)
Best for: fuel flexibilityThis one hedges its bets: it runs on either natural gas or liquid propane, so it’s a reasonable pick if you’re not 100% locked into one fuel source yet, or you’re buying for a property where that could change. It’s rated at 32,000 BTU and comes with remote control.
The tradeoff of a dual-fuel design is that it’s a jack of both trades rather than optimized for either one specifically.
- Works with either natural gas or propane
- 32,000 BTU output
- Remote control included
- Ventless — factor in the safety guidance above
- Not fuel-optimized the way a single-fuel model can be
2. Duluth Forge Natural Gas Insert with T-Stat (FNF300T)
Best for: natural gas + thermostat controlIf your house already runs on natural gas, this one skips the dual-fuel compromise and is built for it specifically. The thermostat control is the real differentiator here — instead of an on/off remote, it holds a set room temperature, which suits a room you heat regularly rather than one you light occasionally for ambiance.
At 26,000 BTU, it’s a step down from the dual-fuel pick above, which is worth noting if you’re heating a larger room.
- Built specifically for natural gas
- Thermostat control holds a set temperature
- Lower BTU than the dual-fuel pick above
- Locked to natural gas only
3. Duluth Forge Liquid Propane Insert (FLF300R)
Best for: propane-only homes
The propane counterpart to the natural gas pick above — same 26,000 BTU rating, same brand, but built for propane from the start rather than adapted after the fact. If you’re on propane and don’t need dual-fuel flexibility, this is the more purpose-built choice.
- Purpose-built for liquid propane
- Remote control included
- Locked to propane only
- Same 26,000 BTU ceiling as the natural gas version
4. ProCom Universal Zero-Clearance Firebox Insert (PC36VFC)
Best for: retrofitting an existing fireplace opening
Different brand, different job: this one is a universal, zero-clearance firebox designed to drop into an existing masonry fireplace opening rather than stand as its own unit. If you already have a fireplace cavity and just want to convert it to gas, this is built for exactly that.
The listing doesn’t spell out BTU or control type, so confirm those specifics directly with the seller if they’re deciding factors for you.
- Zero-clearance design fits existing fireplace openings
- Universal fit, not tied to one specific cavity size
- BTU and control type not specified — confirm before buying
- Ventless — factor in the safety guidance above
5. Duluth Forge Dual Fuel Insert with T-Stat (FDF400T-ZC)
Best for: fuel flexibility with thermostat controlNearly identical to the first pick on this list — same dual-fuel flexibility, same 32,000 BTU rating — but with thermostat control instead of a remote. If you decided you wanted the flexibility of pick #1 but preferred the set-and-hold behavior of pick #2, this is the one that combines both.
- Works with either natural gas or propane
- Thermostat control instead of simple on/off
- Ventless — factor in the safety guidance above
- Very similar to pick #1 aside from the control type — pick whichever control style you actually prefer
Gas Fireplace Insert Buyer’s Guide
Coverage and BTU
BTU output roughly tells you how much room the unit can heat, but bigger isn’t automatically better — an insert sized for a great room will overheat a small den, and an oversized ventless unit is a genuine safety concern, not just a comfort one. Match the rating to the actual square footage you’re heating, and when the listing doesn’t state coverage directly, work out the BTU math for your room before you buy rather than guessing.
Remote vs. thermostat control
A remote gives you on/off and flame-height control, which suits occasional, ambiance-driven use. A thermostat holds a set room temperature automatically, which suits a room you actually heat day to day. Neither is objectively better — it comes down to buying atmosphere versus buying a heat source.
Installation reality
Direct vent units generally cost more to install because they need a path to the outside; ventless units are the cheapest and fastest since there’s no venting to run at all. Actual installation costs vary a lot by home, so get a real quote before assuming either way.
Ventless-specific safety
This isn’t a reason to avoid ventless inserts outright — they’re widely sold and used safely every day — but it is a reason to actually follow the manufacturer’s sizing and runtime guidance instead of treating it like a normal appliance you never think about.
Direct vent and natural-vent installations
Both routes are inherently safer on the carbon monoxide question, since combustion byproducts leave the house rather than the room. The real cost is installation complexity — direct vent needs an exterior wall or a routed vent path, and natural-vent needs an existing or new flue. If your fireplace opening already has one of these in place, that alone might decide the category for you.
FAQ
The Bottom Line
Settle the direct vent vs. vented vs. ventless question first, based on what your house can actually support and what your local codes allow — everything else is a detail by comparison. Once you know the category, BTU sizing and control type (remote or thermostat) come down to how you’ll actually use the room. None of the five picks above is wrong, exactly; they’re built for different setups, so match the setup, not just the model name.
Product availability and pricing on Amazon shift constantly, so the picks above reflect what’s actually in stock right now, and the live listings throughout this page will update themselves if that changes.
Hi, my name’s Eugene Duke and I love sitting by my fireplace reading a book and sipping on an adult beverage. Do you have a fireplace in your house? I’ll help you figure out the best type and style of fireplace for your home.