Yes! A minimum of 20 square inches of ventilation is mandatory for safe and efficient use of a gas fire pit. In a nutshell, placement of the vents should be low on the structure for propane and closer to the top for natural gas fire features. But they are many things to consider in order to create a safe, DIY gas project.
Three Reasons Proper Ventilation Is a Must Have
- Safety. Using propane or natural gas allows you to enjoy the warmth and beauty of a fire feature with the flick of a lighter. However, gas can quickly become dangerous if not handled properly. You must have ventilation or gas can accumulate potentially leading to fire or an explosion resulting in personal injury and property damage.
- Moisture Control. Moisture within the unit caused by rainwater or damp conditions can cause mildew and mold. Air flowing through the vents can help prevent this issue.
- Reduce Heat Build Up. Fresh air circulating inside the structure’s base helps reduce the temperature and keep it from overheating.
Different Gas, Different Vents
Let’s take a closer look at propane versus natural gas. There are some important distinctions between the two that require different applications and will affect the build of your feature.
Propane is widely available, and many people are familiar with it from cooking with a gas grill. That makes it a popular choice for fire features. However, it is considered more hazardous than natural gas for a variety of reasons, so it’s important to understand how to use it safely.
Propane has more carbon and is heavier than air. When it is released into the atmosphere it falls. It can be helpful to think of it like water flowing out of a faucet and collecting in a glass. The gas will pool in the bottom just as water would. Without proper venting, propane will collect in the bottom of your fire feature with nowhere to go.
Propane’s heaviness also means that it takes longer for the gas to be diluted with fresh air and whisked away.
Two other properties of propane to keep in mind, ignition temperature and flammability. Propane can ignite at lower temperatures than natural gas, so the heat source doesn’t have to be as close to spark a fire. Also, it needs a lesser concentration of fuel than natural gas to ignite.
So essentially, propane can be ignited by a heat source farther from the fuel than natural gas and it doesn’t take as much of it. Without proper ventilation, these properties can result in unwanted combustion.
According to the National Fireplace Institute (NFI), there are two ways to safely vent an outdoor propane fire table or pit.
PROPANE IS HEAVIER THAN AIR. As such it will flow downwards and pool in any unvented area.
- One side of the enclosure is completely open. Many people create their fire features in a cart or table. Hiding the propane tank is typically a priority and often DIYers will leave the bottom open (no floor) with several inches of clearance between the ground and the start of each wall. This allows the gas to drop down and be cleared away.
- Properly placed vent inserts. If your build does not have an open side or floor, vent inserts will be necessary. Because propane is heavy, these vents should be located low on the structure. You will need at least two, ideally placed across from each other to create cross ventilation.
Specifics. According to the NFI, the openings should have a total free area of at least 1 square inch per pound of stored fuel capacity. (Most propane tanks are 20 pounds or less, so 20 square inches would be the minimum.)
Overall: One example of an insert that would accommodate the 20-square inch minimum could be configured as a 5” x 4” rectangle.
From the bottom: The lower edge of the insert should be placed no higher than 1 inch from the bottom of the structure. (Remember, you don’t want gas pooling in the bottom of your structure.)
Upper Bounds: The upper edge of the insert should reach no more than 5 inches above the floor level.
If you keep a few important points in mind as you plan, propane is a great way to create your DIY fire feature and allows for maximum flexibility.
Unlike the portable nature of propane, natural gas is fed to homes and businesses via a pipeline. So, if you don’t have access to this system, natural gas will not be an option for you.
Because natural gas is connected to an unlimited supply of gas (via a pipeline), there is greater potential for a catastrophic accident. Therefore, you will need to call a licensed gas installer to make your connections.
They can also help you with placement as there may be regulations regarding the location of your fire feature in relation to existing structures.
In contrast to the heavy nature of propane, natural gas is lighter than air. Using our previous faucet example, instead of flowing down into a cup, natural gas would rise and disperse into the air.
While the expense of setting up your fire feature with natural gas may be more initially than a propane unit, the fuel source is less costly. Plus, you will never have to worry about an empty tank.
With that in mind, it is important to place vent inserts high on the structure, as they won’t do any good placed near the bottom. Be sure to consult the manufacturer’s specific instructions as they do differ from one “outdoor hearth appliance” to another. This is also an area where your gas specialist can be of assistance.
NATURAL GAS IS LIGHTER THAN AIR. Because it’s lighter than air, natural gas will float upwards and dissipate quickly.
Additional Safety Tips
*Gas fire pits or tables should only be operated outdoors in well ventilated areas.
*If you smell gas when operating your fire pit, immediately turn it off and contact a certified gas specialist to troubleshoot the issue.
*It’s good practice to always turn off the propane at the tank when not in use. This not only preserves your fuel supply if there is a leak somewhere in the system, but it also avoids gas from building up and potentially causing an explosive surprise the next time you go out to enjoy your evening.
*Natural gas should be turned off at the outdoor source at the end of the season.
Learning how to handle construct a DIY gas project properly will ensure a feeling of safety and confidence with your finished product. Then, you can just sit back and bask in the glow of your handiwork.
Don’t Be Shy
If you’re still feeling a little nervous about how to handle the venting or you just need a bit more clarification, feel free to contact us. The staff at Celestial Fire Glass is more than happy to help you out.