What is the difference between burning wood, gas, and pellets?

Wood, gas, and pellets are the three most common sources of fuel for heating a home.  Knowing the difference can help you decide which one is best for you and can eliminate unwanted stress when making such an important decision.  Below you will find a brief description of each fuel source, its pros and cons, and the bottom line value of each.


Wood is a traditional source of heat that is burned in fireplaces and stoves.


  • Burning wood offers high heat output without the need for electricity (except for inserts that require a fan to operate)
  • Wood is readily available
  • The price for wood is highly competitive
  • Units that burn wood have very few moving parts; which eliminates the need for costly repairs
  • Wood offers the lowest operating cost of any fuel source
  • Many wood burning units can burn wood and/or gas


  • Burning wood can be inconvenient and messy
  • Installation of wood burning units is more restrictive than other fuel sources (i.e. a vertical vent system is always required).
  • Burning wood requires chimney sweeping
  • Wood burning units are very heavy
  • There is no thermostatic control

Bottom Line

A high-efficiency wood burning stove or fireplace offers the most heat per dollar.


Gas refers to either natural gas (NG) or propane gas (LP) that is burned in fireplaces or stoves to produce heat.


  • Gas burning appliances offer a wide variety of features; such as lights, custom logs (burner), and decorative face plates
  • The heat output of gas units can be thermostatically controlled
  • Installation of gas burning units is less restrictive than wood (gas inserts can be installed into most fireplaces and may be vented vertically or horizontally)
  • Gas units have a large viewing area and have an aesthetic presentation
  • Burning gas is highly efficient and many units can be operated for as little as a penny a day
  • Gas units are offered in a wide range of capacities to meet custom heating requirements


  • Gas units have many components that may require occasional maintenance or repair
  • Propane gas can be cost prohibitive
  • There is no fuel flexibility (only gas can be burned in a gas unit)
  • A gas line is required (restricts installation options)

Bottom Line

Gas units are convenient and offer the greatest customization to help you achieve the design of your home.


Pellets are made from sawmilling byproducts (usually sawdust) that have been compressed into a small, cylindrical shape.  Pellets are burned in a controlled and concentrated manner within a pellet stove.  The quality of pellets can differ greatly between brands and will affect the heating output, efficiency, and sometimes even the maintenance requirements of the pellet unit.


  • Pellet units are very easy and convenient to operate
  • Burning pellets is very efficient
  • Pellet units offer a variety of installation options (freestanding or insert; horizontal or vertical venting)
  • The heat output of pellet units can be thermostatically controlled


  • Pellet units have a lot of working parts and often need maintenance and repair
  • Pellet units require regular cleaning (weekly, monthly, and yearly)
  • Pellet units require electricity to operate
  • There is no fuel flexibility (only pellets can be burned in a pellet unit)
  • Stored pellets must be kept dry

Bottom Line

Not all pellets and pellet stoves are created equal, but a high quality pellet stove offers an easy, efficient way to heat your home.

What type of venting do I need?

The venting system is by far the most important part of a fireplace or stove and must be installed correctly to maintain the efficiency and safety of the unit.  The type of venting required for your system is dependent on the type of unit you have.  Below you will find a brief description of the types of venting typically required for wood/ gas/pellet stoves, fireplaces, and inserts.

Wood burning stoves

Wood stoves use two different types of pipe for the flue venting system.  The vent pipe that goes from the ceiling out through the roof (normally galvanized steel) is Class A chimney pipe; aka triple-wall pipe.  It has the shortest allowable distance from combustible material.  The vent pipe (normally black in color) that connects from the ceiling pipe down to the wood stove can be either double or single wall stove pipe and will typically be 6 or 8 inches in diameter, depending on the installation location and stove requirements.  Unless the manufacturer specifies otherwise, double-wall pipe must be 6″ or more from combustible materials and single-wall pipe must be 16″ or more from combustible material.  The transition connection between the “black” pipe and the triple-wall pipe is almost universal between pipe manufacturers; however, connections between different brands of triple-wall pipe will rarely be compatible.  Note: you can install 6” black pipe (single or double) into existing 8” triple-wall pipe, but you cannot decrease from 8” to 6”.

Wood burning fireplaces 

Even though they burn wood like stoves, zero-clearance fireplaces use air cooled pipe that is usually double-walled with an 11″ to 13″ outer diameter and 8″ inner diameter.  This type of vent pipe is enclosed inside the framed chimney chase and connects the fireplace to the cap at the end of the system.

Gas stoves and fireplaces 

Gas stoves and fireplaces use a direct vent system which consists of a double-wall pipe.  The inner pipe is usually made of aluminum and is 4″ in diameter and the outer pipe is made of galvanized steel (around 7″ in diameter).  Air is drawn down the length of the outer pipe in order to “feed” the combustion inside the fireplace and the exhaust exits through the inner pipe.  This pipe should never be used for venting a wood burning unit.  The pipe is enclosed inside the framed chimney chase and connects the fireplace to the cap at the end of the system.

Pellet stoves (link to pellet pipe)

Pellet stoves use a special pipe, either 3 or 4 inches in diameter, which connects the stove to the cap at the end of the system.  It has a very short clearance to combustible material and is one of the most expensive types of vent pipes on the market.  3” pellet pipe can only be used for 10 feet before it must be increased to 4”.

Wood/gas/pellet inserts

All inserts are permitted to use a flexible pipe since they are installed inside the rigid pipe of the existing fireplace system.  Wood inserts typically use a 6″ diameter, stainless steel liner.  Pellet inserts use either 3″ or 4″ diameter stainless steel liner; the same rule applies when the system extends beyond 10 feet (4” must be used thereafter).  Gas inserts normally use two liners; one for exhaust and one for intake.  Some systems use two 3″ diameter liners and others use a 3″ and 4″ liner.

What is a zero-clearance fireplace?

A zero-clearance fireplace refers to a heating unit (wood and/or gas) that can be installed in an enclosed space with a minimal distance from combustible materials.  The vent pipe for a zero-clearance fireplace is enclosed within a framed chimney chase and extends vertically until exiting the house.  In the hearth industry, zero-clearance fireplaces are sometimes referred to as “builder’s boxes” since they are a cheap way to achieve the look of a fireplace.  Unless they are designed for high-efficiency (such as some wood or gas units and inserts) they offer no real heating output and can be dangerous if not used correctly.  The appearance of zero-clearance fireplaces varies, however the inefficient models share the common characteristic of a dual, bi-folding glass door with mesh screen behind it.  Most of the wood burning models have a gas line in one side of the unit to supply an optional gas log lighter.  The inside walls of a typical zero-clearance fireplace are lined with refractory panels (made of a concrete-like material and shaped to look like brick).  These fake brick panels absorb the heat generated within the fireplace and do not work properly if they are broken or cracked.

The good news is that zero-clearance fireplaces can be safer and “become” efficient heaters by installing an insert (wood, gas, or pellet burning).

What is a masonry fireplace?

A masonry fireplace is just as it sounds, a fireplace made out of brick.  Most masonry fireplaces have an oval-shaped terracotta pipe that lines the inside of the brick chimney and have a rectangular-shaped metal damper above the burn area.  Some masonry fireplaces also have a steel box inside the burn area and a door and/or mesh screen covering the opening.

What is an insert?

An insert is a self-contained unit that is installed inside an existing zero-clearance fireplace to increase its efficiency and enhance its look.  The insert has vent pipe that is installed inside the flue system of the existing fireplace.  There are wood, gas, and pellet burning inserts available; however, the type and size of the existing fireplace limits the type and size of the insert that can be installed.

What is the difference between an insert and a hearth heater?

A true insert is installed inside an existing fireplace (masonry or zero-clearance) with only a small portion, including the door and fans, extending from the opening of the old fireplace.  Flexible vent liner extends from the insert up through the center of the existing flue system to the chimney top.  A hearth heater is set on the hearth of an existing fireplace (the entire unit is exposed) and then vent pipe, usually flexible, is inserted up the flue of the old fireplace.  The fundamental differences between the two are: first, a hearth heater requires much more space in front of the existing fireplace than an insert; second, inserts are more efficient since they directly connect into the existing vertical vent pipe system, whereas hearth heaters must vent at a 45 or 90 degree angle before reaching the existing vent pipe system.

What kind of fireplace do I have and what type of insert can be installed inside in it?

Review the descriptions given for a zero-clearance fireplace and masonry fireplace to see what type of fireplace you have.

To find out what insert options are available to you; send an email to afireplacestorenow@gmail.com and attach a picture of the front of your fireplace.  Include the height, width, and depth of your fireplace as well as any identifying information (usually found on a plate or logo on the face of the fireplace in one of the corners).  We will contact you as soon as possible and let you know what options are available to you.

What is a gas log and which size should I get?

Gas logs are artificial logs that sit on a grate inside an existing zero-clearance fireplace.  A gas log lighter sits under the logs and when the gas is ignited it produces a flame that burns up between the logs to give the effect that the logs are burning.  Gas logs are a great way to add aesthetic appeal to your existing fireplace; and eliminate the mess and hassle of burning wood in an inefficient unit.  There are many different gas logs available on the market, although they vary greatly in appearance and quality.

In order to determine which size logs your fireplace can hold simply measure the width of the back panel in your fireplace.  This measurement corresponds with the appropriate log set size (i.e. width = 15″ or less, get a 15″ log set; width = 18″, get an 18″ log set; etc.).

What is a direct vent gas unit?

A direct vent gas unit is a sealed combustion unit that draws air from outside the home and then expels the exhaust directly to the outside via the venting system.  A direct vent unit may be in the form of a gas stove, gas fireplace, or insert.

What is a B-vent gas unit?

B-vent (sometimes referred to as “natural vent”) gas units draw air from inside the home through ports in the firebox itself and then allow the exhaust to escape through the chimney flue in the same way as a wood burning fireplace.

Will a gas fireplace operate during a power failure?

Only gas fireplaces with a standing pilot will operate during a power failure since no electricity is required to initiate the gas supply and ignite the unit.

What is the difference between natural gas (NG) and propane (LP)?

Natural gas is a lighter gas than propane.  Liquid propane gas contains 2,500 BTUs per cubic foot, while natural gas contains 1,000 BTUs per cubic foot.  It takes twice as much natural gas to reach the same BTU rate as propane.  Natural gas enters your home through a pipeline from a local supplier and propane is stored in a tank on site.  Both natural gas and propane are common fuels that are used to heat gas stoves, gas fireplaces and gas fireplace inserts.  Typically, rural areas do not have a natural gas supply and must use propane.  It is important to know which gas you use in your home before purchasing a gas unit.

What kind of services do you provide?

We offer local installation and maintenance services for all of the products we sell.  This includes repairs on all types of stoves and fireplaces (wood, gas, or pellet).  We also offer cut-to-fit replacement refractory panels for zero-clearance fireplaces.

If you have purchased a product from our website we are happy to provide you with answers to any questions you may have.  If you need installation services and are not in our immediate area you can visit the National Fireplace Institute (NFI) website at www.nficertified.org to find a certified installer near you.  If you are unable to find an installer we will do our best to help you or your contractor install your fireplace correctly and safely.  Give us a call at (760) 949-8300 or email us at afireplacenow@gmail.com

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