Gas logs are a safe, affordable, mess-free alternative to wood logs. They offer you a way to enjoy the beauty and warmth of a real fire without the hassle of dealing with actual wood logs.
Read below to find out everything you need to know about the different styles of gas logs, what they’re made of, how to control them, and how to find the perfect size for your firebox!
Styles of Gas Logs
Vented gas log sets are made to be used in existing wood-burning fireplaces with a functional chimney and are a replacement for real wood logs. Vented logs produce tall, golden flames creating the illusion of an authentic wood fire.
Just like real wood logs, vented logs must be used with a functional chimney and require the chimney damper to stay open at all times to prevent the build-up of harmful combustion by-products, such as carbon monoxide.
Since the chimney damper is required to stay open, almost all of the heat produced is lost through the chimney, making vented logs incredibly inefficient sources of heat.
Burners for vented log sets either come standard or ANSI certified. A standard burner is assembled after you receive it and an ANSI certified burner is assembled at the factory, then tested for safety and efficacy.
Certain cities may require you to have an ANSI certified burner.
- Full & natural flame appearance
- Bigger flame height
- No BTU limit
- ANSI certified & standard burners available
- Expansive ember bed for a realistic look
- Flame can touch logs
- Logs can be rearranged to achieve an aesthetically pleasing display
- Low-efficiency - Roughly only 10% efficient
- Requires venting & the use of a damper clamp
- Heat loss through the chimney
Ventless, or vent-free, gas logs are designed to achieve a clean and smokeless flame. The flames produced are often blue in color and much smaller than their vented counterparts.
It’s still possible to achieve a realistic looking fire, but the fire may not be as large as a vented style can produce.
Ventless gas log sets don’t require the use of a chimney and can be used with the damper closed. Since they don’t require a chimney, 100% of the heat produced is circulated back into the room, rather than escaping up the chimney. This maximizes their heat output and makes them significantly more efficient than vented gas logs.
Burners for ventless gas logs are required by national code to be ANSI certified. They are factory assembled, then tested for safety and efficacy prior to shipping. Ventless burners cannot be modified in any way after they’ve been ANSI certified.
Ventless logs must be stacked around the gas outlets on the burner to prevent flames from coming into direct contact with the logs. If flames do touch the logs, carbon monoxide can be produced. The manufacturer typically determines how the logs should be arranged and will include instructions in the owner’s manual.
As an additional safeguard, all ventless logs come equipped with an Oxygen Depletion Sensor (ODS) to monitor the amount of oxygen present in the room. If the oxygen gets too low, the ODS will automatically turn off the gas.
- 99.9% efficient
- More heat is introduced to the home
- Less gas consumption
- Clean – no messy wood fires
- No venting required
- Comes with Oxygen Depletion Sensor (ODS)
- All burners are ANSI Certified & factory assembled
- Unnatural/unattractive flame appearance
- 40,000 BTU limit
- Burners are pre-assembled & can’t be modified
- Flame can't touch logs
- Logs can't be rearranged
Gas Log Materials
Most gas logs are made from a ceramic fiber or refractory cement mixture designed to withstand high temperatures.
Steel reinforcement bars may be added to the inside of the logs to increase their strength and to prevent them from bending or cracking under extreme heat.
Refractory cement logs are extremely durable and will retain their color and details longer than ceramic fiber logs, which may change color slightly with extended use.
Gas logs are individually cast from real tree samples or created from highly detailed molds to capture the unique characteristics of wood found in nature.
Refractory cement logs are then hand-painted to further detail the wood’s markings, pitting, and coloration to create an authentic-looking replication.
Match-Lit - Match-lit ignitions are the most affordable and simplest control option. All you need is a match or a lighter to ignite the gas. They are only available with vented gas log sets fueled by natural gas.
Manual Safety Pilot - Also known as an SPK, a manual safety pilot kit is a gas valve that incorporates a safety system with a flame-sensing thermocouple. The gas is lit with a match or lighter and if the flame goes out, the safety system will shut off the gas.
Modified Safety Pilot Kits - A modified safety pilot kit is an SPK that has a motor added to the gas valve that lets you connect a remote control or variable control to the gas log set for easy on/off operation.
Millivolt Valve - A millivolt gas valve is similar to an SPK, but instead of a thermocouple, a millivolt gas valve uses a thermopile. The thermopile generates a larger millivolt current than a thermocouple, allowing you to connect a hand-held remote, wall switch, timer, or thermostat to the gas log set.
Electronic Valve - Electronic ignition systems let you control the gas log set with a switch on the gas valve, a wall switch, or a remote control. Some may require the use of household power, but most are battery operated.
Components of a Gas Log Set
- Gas Valve
- Pilot Assembly
- Steel Grate
- Sand or Vermiculite
- Glowing Embers
- Damper Clamp
- Assembly Accessories
Sizing for gas logs is determined by the manufacturer. Always check the sizing requirements and recommended clearances before purchasing a log set to ensure you are getting the proper fit.
Improperly sized logs can overheat your firebox and the gas valves. This can cause permanent damage to your log set, fireplace, and home.
How to Measure Your Firebox
Generally, you can measure the firebox to estimate what size gas logs will fit your fireplace. Simply measure the front width, rear width, depth, and height of the firebox.
If you need assistance with measuring your firebox or would like to get an expert opinion, our Master Hearth Professionals are here to help! Call us at (800) 919-1904 and one of our NFI Certified experts will ensure you find the log set that’s the perfect fit for your fireplace!
Check out our top 6 reasons why gas logs are a great alternative to wood burning fireplaces!
Find out if a vented or ventless log set is right for you!
Read our Gas Log FAQ page for answers to the most commonly asked questions about gas logs.