What you’ll spend

Inserts generally run about $3,000 to $4,000, including installation and a chimney liner, acccording to HPBA.

But don’t rely on any insert as a primary heater; you need a furnace just in case something goes wrong and to protect pipes from freezing in cold climates. 

To choose the type of heater, decide what’s most important to you — burning real wood and having heat even if the power goes out (wood insert), burning a bio-fuel without the hassle of wood (pellet stove), or flipping on fast heat in a specific area of the house (gas).

Wood-burning insert creates real heat with real logs

If a freestanding wood stove is too large to fit into your hearth or the style of your hearth makes it impractical, you can opt for a wood-burning insert — a wood stove without legs. This firebox slides into your existing masonry or metal fireplace and burns real logs.

Your installer snakes a stainless steel liner down your chimney and fits a decorative flange made of black cast iron or steel or colored porcelain around the insert, hiding its steel sides and filling the gap between the box and your hearth. 

A front door with ceramic glass radiates heat into the room. You open the door to stack the wood, then shut it, on most models, while your fire is burning. Most wood-burning inserts also create convection heat with a fan located underneath the firebox. 

Wood-burning inserts can heat anywhere from 1,000 to 3,000 sq. ft., depending on their size. Inserts are small enough to fit into most traditional masonry fireplaces. 

An insert designed to heat 1,500 square feet will burn for three to five hours before you need to reload; for 1,500 to 3,000 sq. ft., you usually have an eight- to 10-hour burn window. 

Green Factor: Efficiency rating of 60% to 80% on U.S. Environmental Protection Agency-certified models.

Downsides:

  • You have to stack and load wood.
  • The insert can be dangerous in a prefab fireplace. “The prefabricated chimney isn’t rated to take the temperature that a wood insert can put out. You need a chimney rated for 2,100 degrees,” says John Mountford, a salesperson at Fireside Warmth in Kingston, N.Y. If you have a prefab, many dealers will recommend replacing the entire fireplace with a high-efficiency wood burning fireplace rather than use an insert.

Install a pellet insert for automated wood fire 

This prefabricated convection heater slides into your existing fireplace — prefab or masonry. Instead of loading logs, you pour in pellets — rabbit-food-sized bits of compressed, recycled wood waste and other renewable substances. 

Like a wood-burning insert, a pellet insert is a sealed combustion box with a partially glass front door, and is surrounded by a decorative flange. It vents through your existing masonry chimney. To operate the system, buy a bag of pellets, pour it in, press a button, and have fire. On some, you just set the thermostat and let the stove do the rest.

Unlike a wood-burning insert, pellet stoves need electricity — to start the fire, operate the blowers, run the auger feeding the pellets to the burn pot, and run the computer board monitoring the system.  

Pellet stoves can heat 1,000 to 2,500 sq. ft., depending on their heat-generating capacity and the size of the fuel hopper. 

Green factor: Efficiency rating of 50% to 80%, according to HPBA; among the cleanest-burning home heating appliances, it uses waste products to create energy. Some stoves can burn alternative fuels such as dried cherry pits, which you can buy in 40-pound bags from hardware and home stores. 

Downsides:

  • Weekly maintenance, such as removing the ash, cleaning the glass, and dusting the electronics.
  • If the power goes out, your pellet insert will, too, (though some have battery backup).
  • A 40-pound bag of pellets runs about $4 to $10, and the average household burns about a bag a day for 1,500 sq. ft.
  • Pellet inserts also lack the off-the-grid romance of heading out back and hacking down fuel yourself. 

Convert to gas for easy heating 

Unlike old decorative gas fireplaces, today’s gas inserts are heat-producing dynamos that use propane or natural gas to power a steady flame dancing on fake logs, decorative modern glass chips, or stones behind a sealed glass face.

Gas inserts can be used in masonry or prefab fireplaces; they can be vented through the existing chimney (or a wall for a free-standing unit). 

Gas is the easiest insert to use and requires very little maintenance beyond the annual check. Flip a switch; have fire. Its best application is for zone heating—turning up the gas in the room you’re in and lowering the thermostat in the rest of your house.

Green Factor: 58% to 85% efficiency rating, says HPBA; very little pollution, smoke, ash, or creosote. Zoned heating allows you to reduce overall fuel consumption.

Downsides:

  • Unlike pellet inserts, burns fossil fuel, making it unattractive if you’re eager to reduce your carbon footprint. 
  • Doesn’t offer the snap, crackle, pop, or aroma of a wood fire.
  • Ventless versions burn very clean — they have to, because they also release pollutants into your home. In fact, some states don’t allow ventless systems.

Savings for all three types

Because fuel prices change constantly, any saving measurements are a moving target. Roughly speaking, yearly savings could range from $64-$255 (based on an average heating bill of $638) if you use an insert for zoned heating and turn down your thermostat, says Wheeler of HPBA.

Permits

Whatever style you chose, you’ll likely need a permit. “If you had a fire, and you didn’t have the permit, your insurance isn’t going to cover your loss,” says Anthony Drago, a manager with Ashleigh’s Hearth & Home in Poughkeepsie, N.Y. Check with your local government about local and state ordinances. 

Asthma and allergies

If anyone in your household has asthma or allergies, consider whether an insert is right for you. Inserts and fireplaces can trigger breathing problems, though proper maintenance and care can help mitigate those issues.

Although no fireplace insert looks exactly like the classic open hearth, they all provide more heat and represent the true pioneering spirit of fireplace heating.