How To Successfully Build A Gas Fire Pit Part 2 – The Fire Pit Structure
Welcome back to our How To Build a Successful Gas Fire Pit series.
In Part 1, we discussed the importance of calculating the available gas supply for your fire pit project and ensuring the correct gas pipe size is installed to meet the needs of the burner.
These decisions are critical because if you’ve planned for a large fire pit with a large burner but fail to provide properly sized gas piping, the gas won’t be delivered at the BTU rating the burner requires.
For example, a large burner such as the 36-inch HPC Torpedo Penta Burner has a BTU/hr rating of 350,000 BTUs with a 3/4-inch gas inlet. If your gas infrastructure can’t supply the necessary BTUs to support the burner, the only viable solution is to downsize the burner’s BTU rating to match the available gas supply. Achieving satisfactory performance with the available gas means reducing the burner size. In this case, you might need to switch to a 24-inch burner, with a BTU rating of 250,000 with a 1/2-inch gas inlet.
We make these calculations first because the size of the burner can significantly influence the fire pit structure’s size, especially from an aesthetic standpoint.
For instance, you may have initially planned for a 4-foot diameter fire pit with a 36-inch burner. However, if there’s only enough gas to support a 24-inch burner, a 3-foot diameter structure might offer a more balanced look.
This series is designed to ensure the correct decisions are made in the proper sequence. If you haven’t yet read Part 1, we recommend reviewing it first before continuing with Part 2.
The Fire Pit Structure Essentials
At first glance, focusing on the aesthetics of the fire pit structure – shape, style, and finish – may seem like the only consideration. While that’s partly true, it’s not quite that simple. It must be carefully designed to meet the specific requirements outlined by the burner manufacturer and relevant safety codes.
For example, a leading manufacturer highlights the importance of proper installation with the following warning:
“Failure to properly vent the enclosure may result in overheating or explosion.”
In fact, venting is not just a manufacturer requirement but a key safety element specified in safety codes, such as the NFPA 1 Fire Code and NFPA 54. Venting helps to prevent dangerous gas buildup and ensure proper combustion.
To guarantee the safety and compliance of your fire pit, always follow the manufacturer’s installation instructions and refer to local building codes. If there’s any discrepancy, follow the stricter guidelines to ensure safe operation and code compliance.
Failure to add sufficient venting can also void the Lifetime Warranty on the burner. All Fire Pit Burners here at the Magic of Fire carry a Lifetime Warranty even when supplied as a component of a Fire Pit Kit such as the Flame Sensing Fire Pit Kits or Electronic Ignition Fire Pit Kits.
What is Fire Pit Venting And Why Is It Important?
The concept of venting a fire pit structure or enclosure is simply to provide a through-draft of fresh air into and out of the fire pit structure.
There are several critical reasons why proper venting must be provided for a fire pit:
- Overheating Protection – As mentioned earlier, overheating can cause significant damage to fire pit components. The constant through draft of air within the enclosure helps replace the hot air with cooler outside air, preventing equipment from overheating. Without proper ventilation, excessive heat can warp the pan, damage electronics or gas connections, and lead to costly repairs or replacements. Over time, it can also shorten the lifespan of the fire pit components.
- Gas Leak Hazard Mitigation – Fire pits contain multiple gas connections within the enclosure. In the unlikely event of a gas leak, the through draft helps disperse the accumulated gas, reducing the risk of hazardous gas buildup and mitigating the potential for dangerous situations.
- Propane Performance – Propane burners are equipped with an Air Mixer Valve that blends air with the propane as it passes through. Without proper venting, the air needed for this process won’t be replenished, causing the valve to “suffocate.” This leads to poor flame quality, reduced efficiency, and the production of excess soot.
Proper venting is essential for maintaining the performance, safety, and longevity of your fire pit system. By following the manufacturer’s guidelines and local codes, you can enjoy your fire pit with peace of mind, knowing that both safety and performance have been prioritized.
How Much Venting Is Required?
The requirement for proper venting is usually specified in the installation manual provided by the manufacturer of the burner. However, there is a consensus on the absolute minimum amount of venting.
Minimum Vent Requirements – A minimum of two vents, each with an area of 18 square inches, must be installed on opposing sides of the fire pit enclosure, for a total of 36 square inches. This is the minimum requirement to ensure that heat and residual gases (such as unburned fuel) can escape safely. While the shape of the vent is not critical, it must meet the required area to allow for proper airflow.
- Additional Ventilation Needs – Additional vents may be necessary depending on the size, material, BTU rating, and intended use of the fire pit. For example, some equipment may require two vents per opposing side or an increase of the total area of the vents to prevent overheating and avoid gas buildup, which could compromise safety and performance.
- Drainage Function – In some designs, the vent can also serve as a drain when installed at the bottom of the sidewall, helping to prevent water accumulation inside the enclosure, which is especially important in areas with heavy rainfall.
- Positioning of Vents – Propane tends to sink and accumulate in lower areas, especially in confined spaces. This property makes it especially important to ensure that propane-burning systems are properly vented, as any leakage can result in the buildup of flammable gas near the ground level. So this would be the ideal position for the vent. Natural Gas is lighter than air, meaning it will rise and disperse more readily into the atmosphere when it escapes. So vents toward the top of the Structure would be preferable.
Venting Summary
Fire Pit Structures must be hollow, and provide sufficient ventilation (a minimum of 18 sq inches on two opposing sides of the structure ).
Selecting Your Gas Fire Pit Location
Wood Burning Fire Pits are very aggressive and uncontrollable, so they need to be located well away from pretty much everything!
Gas Fire Pits are much more controllable, and we have greater versatility in respect to where they can be installed.
However, some consideration must be given to their location, particularly regarding their proximity to flammable materials.
Building Regulations and Codes often have rules about proximity to flammable materials, as do the fire pit equipment manufacturers. It is often the case that the recommendations differ.
In that case, always follow the guidelines that require the greater distance from flammable materials.
For example, if the Codes require 6 feet clearance and the manufacturer recommends 4 feet of clearance, you should comply with the Codes recommendations.
Conversely, if the manufacturer recommends 6 feet clearance, and the codes only recommend 4 feet, you must follow the manufacturers’ recommendations.
Important Note: Clearances increase with the size of the burner to be installed. For example, HPC Fire recommends 84″ of clearance above a sub-200k BTU rated burner. Above 200K BTU that increases to 120″.
The Fire Pit Structure – Other Things to Consider
Drainage: The structure needs to have drainage. If you install the Venting at the very bottom of the structure, it can double as drainage. If the vents are not at the base, then some form of drainage is required to prevent the structure from filling with water during rain.
Access: Inside the fire pit enclosure, there are multiple gas connections, and depending on the ignition system used, there are potentially many other pieces of equipment. Easy access to the inside of the enclosure is essential for maintenance and repairs if and when required.
Gas Valve: Fire Pits must have a gas shut-off valve installed in an easily accessed position on the fire pit structure.
Conclusion of How To Build a Successful Gas Fire Pit
Irrespective of the shape and size of your planned fire pit, its structure must make provision for:
- Venting
- Proximity to flammable materials
- Drainage
- Shut off valve
- Easy access to the inside of the structure for maintenance and repairs