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Natural Gas vs. Propane: What Are the Differences?

Natural Gas vs. Propane: What Are the Differences?

So, you've decided you want a fuss-free fireplace or fire pit and have begun shopping for your new hearth appliance, but you've hit a snag. There are still multiple fuel options, but you keep pondering between propane vs natural gas or natural gas vs propane. This is not completely uncommon.

If it's looking like solid fuel is not a desirable option for your application, a gas-fueled appliance may be the winner. There are many differences between natural gas and liquid propane. We'll cover those here so you have everything you'll need to make a fuel type choice.

What is Natural Gas?

Natural Gas vs. Propane, What Are the Differences?

Natural gas is one of the Earth's cleanest fossil fuels available. Being both odorless and colorless in its natural state, this gas produces mostly carbon dioxide, water vapor, and small amounts of nitrogen oxides when burned. This gas forms deep in the Earth, from long-dead organisms that have been put under high pressure.

Natural gas is most commonly found as the fuel provided by utility companies. Used extensively in residential, commercial, and industrial applications, this is the primary fuel used for residential heating. As of December 2018, natural gas was valued at $4.04 per Million BTU. The primary drawback to the price of natural gas is that you cannot shop around for the lowest cost, as there's usually only one utility company in an area.

Natural gas is also the safer of the two common heating fuels, as natural gas is lighter than the atmosphere and will rapidly dissipate in the event of a gas leak.

Natural gas also has less risk of leaks than liquid propane systems, due to that fact that natural gas flows through more permanent infrastructure. Liquid propane systems require refueling or swapping of tanks, opening up more possibilities for valves and seals to leak with each service or refill. Propane is also regulated to a higher pressure, making loosely assembled pipe joints more prone to leak. If installed with black steel pipe or galvanized steel and tested and pressurized properly, natural gas shouldn't present issues. Only if the piping has spent decades in the elements might it develop a spontaneous gas leak.

What is Liquid Propane?

Natural Gas vs. Propane, What Are the Differences?

Liquid propane is a gas that stands between natural gas and petroleum fuel. Propane is usually mixed with natural gas or petroleum. And, it is formed from the same long-dead organisms under high pressure as the other fossil fuels, but only becomes a viable fuel during the petroleum refinement process. When burned, propane creates water and carbon dioxide. But, an excess or lack of oxygen can have a severe effect on the output.

Liquid propane is used in more rural areas where government infrastructure doesn't exist to pipe heating fuels to homes. Liquid propane is also the most commonly used fuel for grills and portable fire pits. It is easily sold in small 10lb to 100lb tanks. As of December 2018, liquid propane was valued at approximately $7.45 per Million BTU. The number of gallons in 1 Million BTUs equals roughly 11 gallons.

A thing to remember with liquid propane is that it is also colorless and odorless like natural gas. But, unlike natural gas, liquid propane is heavier than the atmosphere. So, it will form deadly pools of gas in the event of a gas leak.

Propane is stored in tanks conducive to its liquid form. Smaller prefilled tanks can be purchased from gas stations, U-Haul locations, farm supply stores, and often from places that barbecue grills can be purchased. Some of these locations will also offer refilling services for propane tanks that you already have. These tanks should never be stored indoors or within 10 feet of a heat source. Propane tanks should be kept upright to protect the integrity of the tank and should only be lifted from the integral handle or moved via a dolly.

Natural Gas vs. Propane, What Are the Differences?
Propane Tanks 101

Liquid propane gets its name from how it is transported in tanks. Under the right amount of pressure and at about -50°F in temperature, propane goes from its gas state to a liquid. This allows for larger amounts of propane to be stored in small areas.

A liquid propane tank should be inspected regularly, especially for portable tanks or older tanks. If your tank is over 10 years old, you will need to have it requalified by a professional. Every five years, the process for requalification must be repeated.

To inspect a liquid propane tank for leaks, you can use leak detection solution or use a common DIY solution of soap and water. Be sure to work in a well-ventilated area. Then, apply the solution around all primary junctions, including valves, regulators, and all welded seams. If bubbles start to form, then there is a leak and immediate action will need to be taken. Smaller tanks should immediately be placed away from potential combustion sources, while larger tanks will need to be safely discharged. Your local fire department will be able to help in these rare situations.

eFireplaceStore is glad to help with any questions about how small of a tank your new liquid propane hearth appliance needs. We offer a standard suggestion. If your hearth appliance is rated at 55,000 BTUs or higher, we recommend a 40lb or larger liquid propane tank. If your hearth appliance is rated at less than 55,000 BTUs, then you can use a 20lb liquid propane tank. These sizes are good benchmarks to allow at least 2 hours of continuous operation, even in extremely cold temperatures.

Of course, you may be thinking our estimate can't be right if your fire pit is rated for higher than 55,000 BTUs with storage space for a 20lb tank. eFireplaceStore makes those suggestions based on the expertise of our NFI Certified Technicians. You can't go wrong with a larger propane tank, but you certainly can go wrong with a tank that is too small for your needs.

How Do They Compare?


Liquid propane and natural gas share some characteristics. Both are clear and naturally odorless, and both are fossil fuels. And, like most heating fuels, the heating capabilities of the fuels are measured in BTUs or British Thermal Units. Additionally, both gases have an additive that allows consumers to smell when there is a gas leak. Usually, this odorant smells like rotten eggs but may be an acrid smell.

Both gases are used in furnaces, boilers, kitchen appliances, and barbeque grills.


But, natural gas and liquid propane are very different gases. It's easier to stockpile liquid propane, as it is commonly sold in portable tanks. Natural gas is almost always distributed by a gas line connected directly to the local utility company pressurization plant.

Natural Gas vs. Propane, What Are the Differences?
Natural vs Propane Gas

On the subject of liquid propane tanks, an undersized tank for the appliance can cause the system and regulator to freeze up. This prevents gas from flowing to the appliance. In this case, you will have to wait for things to unfreeze. It's not easy to say how long you will wait for your regulator to thaw out. It depends on ambient temperatures and humidity. With natural gas, this is not a concern, because there isn't a tank supplying the fuel.

It is sometimes recommended to pour lukewarm water over the tank to unfreeze it; however, there is always the risk of thermal shock that can damage regulators and seals. It is only recommended to utilize this method during an emergency and to keep a close eye on the components while doing to in case damage occurs.

However, the most important difference between the two gases lies in the gas inlet pressure settings for each. This is measured in Water Column (WC). Most often, natural gas is 7 inches WC, where liquid propane is 10-11 inches WC. Without the correct gas pressure through the valve, you could over-pressurize the appliance and potentially cause a gas leak into the home. Or, there won't be enough gas flowing to your new hearth appliance for it to work.

Installing the Gases

Natural Gas vs. Propane, What Are the Differences?

Simply put, it's generally best if you seek help to install a gas line. With the risk of gas leaks, general construction requirements, and more permanent installations, you will likely need to hire a professional. No matter what, a certified technician or plumber must install gas lines for a built-in fireplace. This ensures you meet possible warranty requirements or building codes.

One important thing to remember with any hearth installation is that a flexible gas line will need to be used between the end of the gas supply line and the gas valve in your appliance. So, you should make sure you are using an appropriate length of flex line. Too long of a line and the flex line could crack or whistle from being bent too sharply. Too short and the flex line could crack from the stress. Always use a flex line that is the correct length to bridge the gap.

However, if you're setting up a fire pit with liquid propane, you should have everything you need to install the fire pit in a fire pit kit. The kits include the correct length of flex line for systems with a built-in nook for the tank. The exception of included items, of course, is the propane tank. This means that once your fire pit is set up, you should be able to plug in a tank and light your fire.

Manufacturers of liquid propane-fueled appliances will list the size tank your appliance needs. You can find this information in their installation manual. The manual will also explain how to connect the propane tank to the appliance.

Most vented units can be converted from one gas type to another with a conversion kit. Most fireplace manufacturers offer these kits to customers. But, a vent-free unit cannot be converted due to manufacturer restrictions.

Natural Gas vs. Propane, What Are the Differences?

Make the Decision That's Right for You

In the end, it's up to you as to which hearth fuel you use. Each fuel has unique advantages and disadvantages. And, it is your choice to make the decision based upon your specific application.

Reach out to our eFireplaceStore NFI Certified Technicians with any questions you may have by giving us a call at 1-800-203-1642.

About the Author

Adrienne Devine

Adrienne is our wordsmith in residence, specializing in Content Writing and Editing. During her free time, she reads, writes, makes art, and plays with her two cats, Inkspot and Nicholas. Adrienne also enjoys collecting books and has a personal collection of nearly one thousand well-loved tomes. 

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Customer Q&A with Product Specialists

John W. from Uniontown, Ohio asked:
I have a natural gas well on my property but my "turbo" heater is set up for propane. What would happen if I ran natural gas into the propane heater?
I have a natural gas well on my property but my "turbo" heater is set up for propane. What would happen if I ran natural gas into the propane heater?
That is not recommended. You will want to contact the manufacturer and see if there is an available conversion kit.
Answered by: Kathy O.


Backe H. from Fairfield CT asked:
Can I convert my Petersen natural gas log set to propane? The model is G46 30 11.
Can I convert my Petersen natural gas log set to propane? The model is G46 30 11.
This may be convertible - we recommend contacting Peterson's tech department at 800-332-3973 for more information.
Answered by: Tyler M. - NFI Master Hearth Professional


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