Pellet Burning Fireplace Insert Buyer's Guide
Are you looking to update your current drafty fireplace with a pellet stove fireplace insert? When most people think of a small pellet stove, they envision only free-standing models, but there are pellet stove inserts, too!
We'll walk you through the basics of pellet fireplace inserts, including how they operate, common features, installation, maintenance, brand recommendations, and more. If you have an existing fireplace and want something that offers more efficient warmth, a pellet insert may be the perfect solution.
Why Should You Choose a Pellet Stove Insert?
Pellet stoves are great for anyone interested in a low operational cost, high-efficiency, eco-friendly fireplace. The cost-effective, clean-burning fuel provides better air quality and is a renewable energy source. The maintenance is also less than wood burning stoves. Many models automatically control the fuel intake to maintain your preferred temperature range.
If you want the warmth of a fireplace but are tired of the hassle of wood-burning units, pellet stoves are a great choice. In other words, pellet stoves are the diet soda of wood burning stoves - all the great taste with less to worry about.
Differences Between a Pellet Stove and a Pellet Stove Insert
Pellet stove inserts are legless pellet stoves. Unlike free-standing models that sit on a pedestal or legs, a pellet stove insert is designed to fit inside a fireplace opening. Both pellet stoves and inserts also come in models that are suitable for bedrooms, bathrooms, and mobile homes.
Pellet inserts have the main components of a pellet stove and operate in a similar way. They have the same degree of efficiency and use the same types of fuel. The main differences between pellet stoves and pellet inserts have to do with installation and venting.
As the name suggests, some pellet inserts can be installed inside framed openings as built-in models. They are also designed to fit into your existing masonry or prefabricated fireplace. Sizing the opening is important, and we'll cover that in a separate section later.
When installed into a masonry or prefab fireplace, pellet inserts use a flexible liner system. Models that are installed into a framed opening must use rigid venting. Flex liners connect to the back of the stove and travels up the chimney, while rigid venting is routed through a cavity and through the roof. Unlike free-standing pellet stoves, there are no horizontal venting options for pellet inserts.
Free-standing pellet stoves use either an electric or gravity-fed fuel system. Electric versions use an electrically-powered auger to feed pellets into the burn chamber. The gravity system does not require electricity since the pellets simply fall into the burn chamber. Pellet inserts do not come with the option of a gravity-fed fuel system and must have electricity. This is due to height limitations that make a gravity fed system impossible.
Another difference is the flashing assembly or surround that comes with pellet stove inserts. The flashing conceals the space between the edges of the appliance and the opening of the fireplace. It is basically a frame on the front of the fireplace that gives it a finishing touch and covers any gap between the unit and the hearth opening.
Pellet stove inserts are available in models that heat up to 2,000 square feet. Free-standing pellet stoves are available in even larger models, including ones that resemble a home furnace.
For information on free-standing pellet stoves, take a look at our Pellet Stove Buyer Guide.
How Do Pellet Stove Inserts Work?
As mentioned above, pellet stove inserts operate in much the same way as a regular pellet stove. Although they have slightly different venting requirements, the burn chamber, pellet auger, and ash removal are the same. Pellet stove inserts also come with the safety features of regular pellet stoves.
A hopper holds the pellets until they are fed into the burn chamber for combustion. Pellet stove inserts use a mechanical auger to draw pellets from the hopper into the burn chamber. A grid or mesh in the bottom holds the pellets in place while letting the ash fall into a tray beneath.
The pellets are lit by a special igniter and a combustion fan supplies oxygen to the flames. The combustion fan varies its speed to help control the heat output of the burn. It also helps move exhaust air through the vent to the outdoors. Some models also use a secondary fan for this task.
Heat exchanger tubes are located directly above the burn chamber, and the air inside them is heated by the burning pellets. A convection fan moves air through these tubes and into the room.
Pellet stoves and inserts also have several fail-safes and sensors. This includes a hopper door lock and a vacuum switch that makes sure the combustion fan is running. There is also a temperature system that monitors heat and will shut down if it detects overheating. The convection fan/blower controls the burn rate and temperature.
Since the combustion chamber is completely sealed within a steel and glass housing, smoke cannot enter the home. Instead, all smoke and light ash is blown by the combustion fan to the outside vent.
Some pellet stoves offer fully thermostatic operation with a built-in room temperature sensor.
What Fuel Do Pellet Stove Inserts Use?
Owning a pellet stove insert is no different from having a small pellet stove; both run on compressed biomass. That's a fancy term for little pellets made of biomass like sawdust or corn. Other biomass material includes things like soybeans, cherry pits, and olive pits.
Some stoves burn better with certain types of pellets. Before burning pellets other than wood, check that your stove will work with alternative pellet fuel. For example, corn pellets have a higher sugar content that lead to more frequent maintenance requirements.
What Are The Pros and Cons of Pellet Stove Inserts?
Pellet stoves are relatively low maintenance and have high-efficiency ratings. However, there are some limitations. Here is a breakdown of the pros and cons:
- Pellet fuel burns more efficiently than logs and creates less ash.
- Both pellet stoves and pellet stove inserts are easy to operate and allow for a wide range of burn rates.
- The ashtray makes ash removal more convenient than wood-burning models.
- Many models have a hopper that regulates how much fuel is fed into the burn pot.
- Excellent heat efficiency, able to heat over 2,000 square feet depending on the model.
- Pellet stove inserts are restricted to vertical venting only.
- Inserts require a 120-volt power supply.
- Somewhat limited to mostly traditional styles and designs.
- Limited circulation abilities.
What Features Are Available With Pellet Stove Inserts?
Pellet stove inserts come in a range of sizes and heat ratings. In addition to decorative accents, they are packed with features that offer safety and convenience.
For example, the Napoleon NP145 Black Pellet Burning Fireplace Insert can generate up to 42,000 BTUs. That's enough to heat approximately 2,000 square feet! Starting fires is easy with the auto ignitions system and it has a hopper capacity of 45 pounds (which lasts up to 45 hours).
Automatic cleaning features include an auto-purge cycle that cleans the burn pot every 60 minutes. It also has an air wash system designed to keep the glass clean.
This model is rated for bedrooms, bathrooms, and even mobile homes. Just make sure you follow all of the clearance restrictions for a safe burn.
If you're looking for a stove that can burn more than just wood pellets, check out the US Stove Corn and Pellet Burning Fireplace Insert. Along with wood pellets, it burns corn, soybeans, cherry pits, olive pits, and other compressed biomass fuels.
The stove heats 1,000 to 2,000 square feet and generates up to 52,000 BTUs per hour. It features nine blower and heat settings so that you can fine-tune the heat output.
The burn pot has a built-in agitator that helps keep it clean during operation. The insert also comes with a clean glass air wash system. This model is approved for use in mobile homes as long as you install a fresh air kit.
Since their original development, pellet stoves have blossomed into a well-accepted hearth platform that is manufactured by numerous sources. Below are some of the best brands on the market.
Napoleon — Offering the long-running NPI45 and TPI35 pellet inserts under the Napoleon and Timberwolf brands, this manufacturer has continuously refined their pellet designs to result in very reliable and well thought out products that can be trusted to heat reliably for years.
Quadra-Fire — This manufacturer focuses on producing pellet burning models that not only function well but make a welcome addition to the décor of a room. Detailed and handsome surrounds and glass overlays make for a product that is sure to start a conversation.
US Stove — A manufacturer of value-oriented multi-fuel inserts, their products are simple, easy to use, and simple to service. Able to burn a broad range of different bio fuels such as cherry pits, corn, or compressed grass pellets, US Stove pellet inserts are among the most versatile on the market.
Harman — Consistently high quality and attention to detail during production have led to the best selling models for this manufacturer. Featuring fine craftsmanship melded with unwavering reliability, Harman pellet inserts are consistently the top-rated models on the market.
How Can You Get More Out of Your Pellet Fireplace Insert?
Accessories like the ones listed below can increase performance, aesthetic, and convenience.
You can extend the length of your burn time by adding a hopper extension. The extension increases the amount of pellet fuel your hopper can hold so you don't have to refuel as often. An outside air kit is another option for increasing performance. It allows for a steady flow of combustion air that results in a more efficient burn.
Enhance the look of your pellet stove fireplace insert with accessories like a decorative liner or log set. The liner adds depth to the fireplace and the log set makes it look more like a traditional fireplace.
You can also add decorative accents like trivets to complement the decor of your home.
The control panel for the stove is usually located on the unit. Handheld remote controls make operating your pellet stove insert even more convenient. You can buy basic on/off controls or opt for thermostatic remotes that allow you to adjust the temperature. There are also wall-mounted options available.
How Do I Choose The Right Size of Pellet Stove Insert?
Start by measuring the size of the fireplace that the pellet stove insert will fit into. Most insert models fit a range of opening sizes, so you have some flexibility. Once you know the dimensions, you can choose a model designed to heat the square footage of your room.
To find the dimensions of your fireplace, use a tape measure to measure the front width and height. Next, measure the depth and the back width of the opening. Lastly, check to see if the back of your fireplace slopes forward. If so, note the smallest depth at the top of the fireplace.
While most fireplace openings are tapered, fireplace inserts are not. The width of inserts is usually the same or nearly the same from front to back. Most models offer at least two sizes of surrounds to cover the space between the fireplace insert and the fireplace opening. Be sure to not only select a surround that will completely cover the opening of the fireplace.
Next, you need to address venting. Check that you have enough space to install a liner between the flue collar of the fireplace insert and the damper area of the fireplace itself. Some masonry fireplaces have thick lintel areas or narrow smoke chambers. It may be necessary to modify the fireplace to make room for the fireplace insert venting. If you have questions about choosing a model, our NFI certified technicians are glad to help.
Now that you know what dimensions you need, you are ready to choose a fireplace insert. Heating output is measured in BTUs and reflects how much heat the appliance releases when burning. Remember, bigger is not always better.
Choose a fireplace insert designed to heat only the square footage you need. Selecting an insert that is too large or too small can leave you dissatisfied. Most manufacturers state the approximate square footage each model is designed to heat.
How Do You Install a Pellet Stove Insert?
The first step is to prepare the fireplace opening for the insert. This may include grinding down uneven masonry. You'll also need an outlet for the power supply. After that, the main consideration is proper venting. We recommend hiring an NFI Certified professional to do the installation.
Preparing the Fireplace Opening
Pellet stove inserts come with a flashing assembly to cover the space between the edge of the appliance and the opening of the fireplace. The flashing acts as a frame around the fireplace insert.
Before you buy a fireplace insert, make sure that the flashing will cover the gap. If you order a fireplace insert that is too small for your fireplace, the flashing will not extend far enough to hide the extra space.
If your fireplace opening is made with masonry or brick, you may need to smooth the edges of the opening so that the flashing can sit flush with the masonry. A grinder is suitable for brick or stone. For material like slate that is prone to shattering, we recommend screeding a small amount of cement around the opening. This creates a smooth surface without grinding.
Pellet stove inserts require a 120-volt power supply. You can have a power outlet professionally installed in the opening of your fireplace. If that is not an option, you can use a panduit to conceal a power cord that runs to a nearby outlet.
The vent collar on pellet stove inserts is on the back of the appliance. Pellet-burning inserts use a flexible liner system that extends up the chimney.
Liners are secured to the top of the chimney using a top support, clamp, and cap. Most models have a 3-inch diameter outlet and use a 3-inch liner for a maximum of 10 to 15 feet. If you need to route the liner longer than 15 feet, size up to a 4-inch liner.
We recommend installing a cleanout tee near the flue collar of the stove. This way you can clean the liner without having to disconnect it.
The inserts have an air intake on the back that is usually two inches in diameter. The flashing on the front blocks most of the air that the stove can draw from the room. We recommend installing a flexible aluminum or similar air induction pipe to the chimney flue. This allows the stove insert to draw air from the chimney instead of relying on room air. Manufacturers should specify the type of materials you'll need to do this.
How Do I Care For My Pellet Fireplace Insert?
Maintenance for a pellet insert is similar to that of a regular pellet stove. The main difference is that you need to clean the chimney liner. Other than that, follow the operating instructions and regularly clean up the ash. With proper care, your stove should last 15-20 years or longer.
If you have the recommended cleanout tee, you can clean out the chimney liner on your pellet insert without taking apart the venting system. You will need to remove the flashing and scoot the insert forward to gain access to the tee. Remove the cover of the tee and sweep out the liner.
Here are some other maintenance tips to help you keep your stove in excellent condition:
- Always read and follow the manufacturer's instructions.
- Use only the fuel recommended for your appliance.
- Watch for excessive fly ash that can stick to heat exchanger tubes or the inside of the vent pipe.
- Use cleaning brushes with lightweight flexible rods to sweep out the vent system.
- Empty and rinse the ash pan frequently
- Check the igniter to make sure it is working properly.
- Do a more thorough cleaning during the offseason and remove the pellets from the hopper.
How Will My Pellet Fireplace Insert Ship?
Pellet stove inserts typically ship via freight and will arrive packaged on a pallet. You can expect the freight company to call and schedule a time frame to deliver the shipment to your home or business.
Always make sure you inspect the delivery thoroughly for any damaged or missing parts before you sign off on the delivery. Once you sign off on the delivery, the freight company is no longer liable for any damages.
If you do notice any missing parts or defects, contact the manufacturer right away. Some companies have limited warranties that expire within the first few days.
Pellet fireplace inserts are a great way to revamp an old fireplace opening with an eco-friendly, efficient appliance. Pellet stove inserts are similar to free-standing pellet stoves, but make sure you are familiar with the important differences.
It may take some time to find a model that fits in your fireplace opening and provides the right amount of heat, but it is worth it! You'll soon be enjoying the lower maintenance, easy operation, and toasty heat.
Please let our NFI Certified Technicians know if you have any further questions. We are happy to help!
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Pellet Burning Inserts Q&A with the NFI Certified Specialists* Please Note: All customer questions are answered by our NFI Certified Specialists free of charge!
from Elkhart, IN asked:
November 21, 2019
Is it possible to burn corn in a pellet stove or are there specific units for doing either?
from Sacramento CA asked:
October 16, 2019
Where can you place the 120-volt outlet, before placing the pellet stove insert?
This will depend on your application and local building code requirements. We recommend contacting a local electrician before proceeding.
Tyler M. - NFI Master Hearth Professional
on October 16, 2019
from Bloomfield, CT asked:
October 6, 2019
Is there a pellet stove insert that can heat roughly 600 square feet of space?
You can check out our selection of pellet stoves here
. Any of these are great options for a space that large.
on October 11, 2019
from Yorktown, VA asked:
March 26, 2019
is there a pellet stove insert to replace a corner gas log set?
Unfortunately, we do not have any that would fit a corner unit.
on March 26, 2019
from Dairyland, WI asked:
April 18, 2018
Can I put this in a wall cavity?
No it can not.Inserts can only be installed into an existing brick/masonry fireplace and not a wall.
on April 18, 2018
from Pennsylvania asked:
October 21, 2013
When installing a pellet stove insert, what type of flue liner is required? Is it necessary to run the flue liner all the way the the top of the chimney and cap it? Or can you run the flue liner to just below the chimney cap?
Both wood burning and pellet inserts are very much the same in the fact that they should use a 304 or 316 stainless steel liner system, flexible or rigid, that is sized to the opening of the flue collar on the appliance. The liner can indeed be supported and terminated just below the existing chimney cap. It is not necessary to use a factory top plate and cap, if the existing cap is in good condition. Metal strapping or fabricated brackets can be used to support the liner.
Collin C. - NFI Master Hearth Professional
on October 22, 2013