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How to Choose a Gas Log Set

Mar 18th 2021

Gas logs come in two basic varieties, vented log sets and vent-free log sets. A vented gas log must be used in a regular fireplace, designed to burn a wood fire. Vent-free gas logs can be used in a regular fireplace or can be used in a prefabricated vent-free firebox that has no chimney.

Some vented gas logs will give up to 25,000 BTU's of heat but most don't give hardly any heat. If you are primarily interested in a large flame and don't care much about receiving heat from the log set then a good choice is a vented gas log.

On the other hand if you are expecting to get heat from your new log set then you will want to consider either a vent-free model or a vented gas log that is rated to give heat (most aren't) or you can go with a vented gas log set and a Gas Log Heater. The Gas Log Heater will provide up to 25,000 BTU's of heat into the room and can be used with or without glass doors.

If you have a see-through fireplace (a fireplace you can see through) then you'll need to look at sets that are specifically designed for a see-through fireplace. These sets will be finished on both sides of the logs where regular gas log sets are only finished on the front side.

When shopping for a gas log set there are several things to consider. A cheap price usually means something is missing or the quality is low. The higher priced log sets have more detail to their logs and better burner systems, producing a bigger and nicer flame pattern.

A few things to consider...

How realistic are the logs? If you take a good look at the picture (which will show full-size when clicked on) you will see that the logs are very detailed including the charred look and grain of the wood. Cheap log sets look fake. Count how many logs are in the set since many sets from other companies consist of only four logs.

How Big is the Flame? While flame size can vary depending on each homes gas pressure, typically you will see a flame similar to the picture shown. Many gas log sets have a small flame due to the poor burner design. To cut costs many stores sell the least expensive burner that typically produces a small or fake looking flame.

Will I Need A Safety Pilot? With a vent-free set the safety pilot is included, most vented sets have an optional valve or safety pilot, or wall switch/remote control option. Pick the option that suits your needs. For vented logs we suggest you purchase the safety-pilot or remote option (remote option includes safety pilot). With a standard gas valve you will need to light the fire each time you use the log set versus the safety-pilot where all you need to do is rotate the knob and the fire will light. If using LP (propane) then you must use a safety pilot valve.

Vented vs. Vent-Free Gas Log Sets

Vented Gas Log Sets

A vented gas log set simply means that you will need to vent the gas fumes up the chimney. While vented log sets are very popular due to their large flame pattern and realistic look, they are the least efficient since most all the heat is going up the chimney. Flame size is typically larger since vented sets usually burn more Btu's of gas. A vented gas log set must be installed in a wood-burning fireplace and ran with the damper wide open. Vented log sets have the option of connecting to a manual on/off gas valve which is lit with a match, or can be connected to a manual safety pilot or a millivolt pilot valve.

Size 18" 24" 30"
Natural Gas 70,000 BTU Input Rating 80,000 BTU Input Rating 90,000 BTU Input Rating
Propane Gas 46,000 BTU Input Rating 46,000 BTU Input Rating 60,000 BTU Input Rating
Vented Gas Log Sets
Advantages: Realistic looking - Lower purchase cost - Large flame
Disadvantages: High BTU input - Lower heat output

Vent-Free Gas Log Sets

Vent-Free gas logs lower heating costs two ways - they require about half the fuel as compared to conventional vented gas log sets, and they operate with the fireplace damper closed. This means that you're sending the heat into the room, not up the chimney - a definite plus with fuel costs so high. Typically the flame size is smaller and consequently not as realistic as compared to vented log sets. However vent-free log sets burn up to 99.9% efficient and put that heat into your home. A vent-free gas log set will easily heat an average sized room or more. Many vent-free sets can be connected to a wall thermostat or remote control with a thermostat and used as supplemental heat.

Vent-free gas logs are available in two types of logs, ceramic fiber logs and concrete refractory logs. The ceramic fiber logs will glow after about 15 minutes of use giving a more realistic burn where the concrete refractory logs will not glow at all but are more durable and intricate in their detail.

All vent-free gas log sets come complete with a gas valve but you may have a choice on either a manual safety pilot gas valve or a millivolt gas valve. See Picking a Gas Valve for more information.

Vent-free gas log sets are for use in wood-burning fireplaces or approved vent-free firebox enclosures. Glass doors must be open when burning. With adequate combustion and ventilation air the damper may be closed for vent-free use. The damper may be slightly opened for reduced venting. Check local codes and ordinances for permitted uses. Vent-free appliances are illegal in Minnesota and Canada, for instance.

Size 18"-21" 24"
Natural Gas 26,000 BTU Input Rating 38,000 BTU Input Rating
Size 18" 24"-30"
Propane Gas 32,000 BTU Input Rating 38,000 BTU Input Rating
Vent-Free Gas Log Sets
Advantages: Burn less fuel - High heat output - Back-up heat source
Disadvantages: Smaller flame - Higher purchase cost

Measuring for a Gas Log Set

Your log set should be properly sized to your fireplace using the following guidelines:

Measure your fireplace taking the front width , the rear width and the depth.

The log set size you can use in your fireplace should meet the minimum dimensions.

"A" - Minimum 2" to 6" on each side of the nominal set size. In other words, if you are planning to use a 24" log set, the front opening dimension of your fireplace should be at least 28".

B" - Not less than nominal set size. In other words, if you are planning to use a 24" log set, the rear dimension of your fireplace should be at least 24" wide.

"C" - Minimum 12" to 14" (16" to 18" for see-through fireplaces).

Be careful when measuring a Pre-Fab fireplace, typically you will need a 36" fireplace (A dimension) for a 24" log set.

Picking a Gas Valve

Gas valves come in three varieties, manual on/off, manual safety pilot, millivolt safety pilot.

Manual On/Off Valve

The manual on/off gas valve requires you to light the match, open the gas valve and adjust the flame as desired. A manual valve is not allowed on LP gas (liquid propane) log sets. While the least expensive, it can be hazardous since a small child could open the valve allowing raw gas to enter the home. Manual valves are not used on vent-free sets. See our Gas Valves Section to purchase.

Manual Safety Pilot Valves

The manual safety pilot is similar to a gas valve seen on a furnace or water heater. Initially you turn on the valve to the pilot position, push it in and hold a match to the pilot opening. It has a standing pilot (flame) that burns as long as you have the valve in pilot or on position. Turning the valve to the On position lights the gas logs and has some flame adjustment. Turn the valve to the pilot position to turn off the logs. The pilot can be turned off completely in the summer months to save fuel. See our Gas Valves Section to purchase.

Millivolt Safety Pilot Valves

The millivolt safety pilot valve is similar in operation to the manual safety pilot valve except that the valve can be connected to optional devices to turn on/off the gas. They can be connected to an on/off switch, a wall thermostat, or can be operated with a hand held remote control. Remotes vary with the less expensive version having only on/off functions where the more expensive remotes also can control the flame height and/or have a built in thermostat control which will lower or turn off the gas log set when the set temperature is reached. The latter version is not useful on vented log sets since vented logs produce little heat. See our Gas Valves Section to purchase.

Gas Log Grate Heaters

Heater Grates are a great way to get heat from a vented gas log set or from a wood fire. The hollow grate will get hot from the fire and the thermostatically controlled blower will automatically come on blowing heat into your room and shut off after the fire dies down. The blower speed is adjustable allowing you to control the heat output into the room. Two designs are available, one for vented gas logs, the other for wood burning. Can be used with or without glass doors.

EmberAir Grate Heater

The EmberAir Grate Heater can be used with either a vented gas log set or in a wood burning fireplace. The hollow titanium tube is typically routed up and over the rear of the fireplace grate so the heat from the fire warms the tubing. Thermostatically controlled with a two speed blower.

Gas Log Heater

The Gas Log Heater allows you to slide the burner pan from your existing gas log set under the rear hollow tube of the heater grate. When the gas fire heats up the hollow grate assembly the fan automatically comes on forcing up to 25,000 BTU's of heat per hour into your home. Can be used most vented gas log sets and is designed for use in a masonry fireplace. Rheostat and Thermostatically controlled. 2 Year Warranty.

Cozy Grate Heater

The perfect companion for any masonry fireplace. Tired of loosing all the heat up the chimney? Get up to 40,000 BTU's of heat from your wood fire with the Cozy Grate Heater. When the wood fire heats up the hollow grate assembly the fan automatically comes on forcing up to 40,000 BTU's of heat per hour into your home. Rheostat and Thermostatically controlled. 3 Year Warranty.

Gas Log Testing Laboratories

Most municipalities do not require any special approval on a gas log set, however, some do. The state of Massachusetts and the city of Los Angeles are particular about what they will approve. You should always check with your local city or township to see if there are any requirements that need to be met before purchasing you new gas log set. You may find that your city may require a RADCO, or AGA, or ANSI, or CSA approval before they will pass the inspection. Each gas log set we carry will list the approval if it has one, some don't. That doesn't mean they aren't safe, it only means the company hasn't tested this particular log set with an outside testing firm. You will find that a gas log set that carries a label from RADCO or AGA, etc. will cost more than an identical set that isn't approved. If you don't need the approval for you town then it isn't necessary to pay the extra money if you have an option.

  • RADCO - The RADCO approval tests gas logs for safety. The log set does not necessarily need a safety pilot assembly.

  • AGA or ANSI - "ANSI" stands for American National Standards Institute. It is a standards organization that approves the development of standards for gas hearth products, as well as many other products in the US. The AGA or ANSI standard approves the gas log set only if it has a factory installed safety pilot assembly.

  • CGA - CGA, Canadian Gas Association is a standards organization for Canada which approves and holds the gas safety standards for Canada.

Testing standards are changing rapidly in the Hearth Industry.

Note: All gas log sets should be installed by qualified service personnel, typically available in the Yellow Pages. Read Owner's Manual supplied with set before installing and using log set.