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    Which Gas Logs Are the Right Size for Me?

    Now that you've gone through the steps of making the really broad decisions in selecting your gas logs, it's time to get a little more specific. This is the point at which most gas log shoppers begin narrowing down the vast selections of ventless or vented gas logs based on things like fireplace size considerations, types of controls, pilot systems vs. manual gas valves, and others. On this page, we'll take a look at each of the factors that can really make a difference in choosing the right gas logs.

    Which Gas Logs Are the Right Size for Me?

    If you're going with ventless gas logs that come in their own cabinet you don't have to worry too much about the size. For the rest of you, though, selecting a set of gas logs that you like and that fits properly within your fireplace is a must. You can simply use the handy-dandy gas log calculator located here on, but let's run through some basic size considerations so you know exactly what you're looking for.

    Gas Log Sizing Factors

    Fireplace Measurements:
    • Relevant fireplace dimensions for choosing gas logs include the width of the front opening of the fireplace, the width of the rear fireplace wall, the height of the front fireplace opening, and the fireplace depth from front opening to rear wall
    • A minimum of 2 inches on both sides must be maintained between the gas log burner system equipment and the fireplace sidewalls, and some customers prefer up to 6 inches on both sides
    • The gas log set chosen should not be longer than the width of the rear fireplace wall
    • Fireplace should be a minimum of 12 to 14 inches deep for almost any kind of gas logs

    Control Systems:
    • Don't forget — when selecting gas log sizes based on the burner system equipment, you MUST allow room for the fuel control system your gas log burner uses (for more information, refer to the Quick Reference section below)
    • We'll discuss each in detail in the next section, but for the purposes of choosing gas logs the three basic types of fuel control systems to consider are Manual on/off gas valves, Manual safety pilot valves, and Millivolt or remote-ready pilot valves

    Aesthetic Concerns:
    • Choosing a gas log set that is too large for the fireplace can affect the burn and hamper the operation of the fuel control system
    • Choosing a gas log set that is too small can diminish the beauty of the hearth setting
    • Selecting a gas log set that is either too large or too small can adversely affect proper fireplace drafting

    Types of Fuel Control Systems

    As promised, here's where we take a closer look at the three main types of gas log fuel control systems. Check them out to see how each works and which system appeals to you, then we'll wrap this page up with a quick look at the sizing implications of each system.

    Manual On/Off Valve

    This is the simplest type of fuel control system, the one many of us used in years past. You turn a manual on/off valve open and closed by hand, light the gas log burner with a match, and adjust the flame height via the valve by hand, as well.


    • Easy to operate
    • Least expensive fuel control system
    • Uses the least amount of space in the fireplace


    • Manual valves are NOT ALLOWED for use with liquid propane
    • Manual valves are not used with ventless gas logs
    • Potentially hazardous as a child can possibly open the valve, releasing raw gas into the home

    Manual Safety Pilot Valve

    This fuel control system is similar to that used on a furnace or water heater. There are 'Off', 'Pilot', and 'On' positions. Initially you have to turn the valve to the 'Pilot' position and light the pilot with a match, but after that you can turn the gas logs on and off by switching between the 'On' and 'Pilot' positions. The pilot will stay lit until turned to 'Off' or blown out, at which point it automatically shuts off gas flow. Propane gas logs require a safety pilot valve of some kind.


    • Still relatively simple to operate
    • Can be turned off in the summer months to save fuel


    • Still requires manual lighting of the pilot flame
    • Somewhat limited flame control in the 'On' position
    • More expensive than manual on/off valve to purchase
    • Uses slightly more fireplace space than a manual on/off valve

    Millivolt (Remote-ready) Pilot Valve

    This is very similar to a manual safety pilot valve, except a remote-ready pilot valve can be connected to an optional device to remotely turn the gas on or off or control the flame height. These devices range from inexpensive remotes or wall switches designed only to turn the gas on and off to more expensive remotes that can adjust flame heights and set timers, or even thermostats that will turn the flame down once the desired temperature is reached.


    • Remote operation, requiring no manual lighting of the pilot
    • Maximum user flexibility
    • Allows for many devices, some of which can be changed as needs change


    • Most expensive fuel control system
    • Takes up the most space in the fireplace of any fuel control system

    Quick Reference

    Some final tips to give you an idea about how each gas log fuel control system affects the size gas log set you need. This reference is somewhat general and some gas log sets may have individual space requirements, so read the information about individual gas log sets carefully!

    Manual On/Off Valve

    No pilot kit is involved, so all you need is 2 inches of clearance between the burner system and the fireplace on each side. Measure the fireplace's front opening width, subtract 4 inches, and the resulting length is the largest size gas log set your fireplace can accommodate.

    Manual Safety Pilot Valve

    The safety pilot valve occupies some space, so again measure the front opening width of the fireplace, but subtract 8 total inches rather than the 4 inches required for the manual on/off valve. The resulting measurement is the largest gas log set equipped with a manual safety pilot valve your fireplace can handle.

    Remote-ready Pilot Valve

    This is about the same as the manual safety pilot valve calculation, but in this case subtract 12 inches from the opening width to find the largest gas log set equipped with a remote-ready pilot valve suitable for your fireplace.

    About the Author

    Collin Champagne

    Approaching his 10-year work anniversary, Collin is one of our National Fireplace Institute (NFI) certified technicians and content manager for the eFireplacestore, eCanopy, and EliteDeals brands. He is a Master Hearth Professional, which means he is certified in all three hearth appliance fields — wood, gas and pellet.

    When not at work, he spends time with his wife, Lindsey, and his sons, Samuel and Eli, on their ranch enjoying their many animals. Completing projects around the ranch and spending quality time with his family are among his greatest joys. 

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    Questions About This Article

    All customer questions are answered by our NFI Certified Specialists free of charge!
    4 Questions & 4 Answers
    from wva asked:
    July 28, 2021

    Does the 18-inch logs produce less heat than the 24-inch?

    1 Answer
    The size of the burner BTU output will determine the heating capabilities of the appliance, not the log size.
    Submitted by: Aaron D. on July 29, 2021

    Linda M.
    from Ooltewah, TN asked:
    February 5, 2020
    We can only turn the flame to low on our ventless gas firelogs and it is still too hot for our vaulted great room. Could the log set be too large for our fireplace?
    1 Answer
    It very well could be too many BTU's for that area. As well, vent free logs are only meant to be run up to 4 hours at a time.
    Submitted by: Owen O. on February 6, 2020

    from Riverside, CA asked:
    October 23, 2019
    If you use a manual gas on/off switch do you have to leave the flue open when gas logs are off?
    1 Answer
    Yes. The only difference would be at the end of the season when the gas is shut off completely. Only then may a damper be fully-closed. 
    Submitted by: Will M. on October 23, 2019

    Jennifer S
    from Morgan Hill, CA asked:
    August 24, 2019
    How do I decide between a 24" and 30" vented log when both will fit in my fireplace? Are these units placed more to the front of the fireplace?
    1 Answer
    Each model of gas log set is unique and will list in its installation manual the minimum required dimensions of the space it can be placed in. Log sets are most commonly centered both front to back and left to right within the space they are placed. The "rear width" requirement in most manufacturers literature usually refers to the width required at the depth given -- there is no requirement that the log set be placed against the actual rear of the firebox. When both a large or smaller set will physically fit, the choice becomes an aesthetic one. While some people like to maximize the view of the "art," others find larger sets to look artificially big compared to traditional split real wood. 
    Submitted by: Cortney O. on August 26, 2019

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