The performance of an outdoor gas fire feature depends on the proper balance of two closely related factors: gas pressure and gas flow. Pressure is the force that moves gas through the system, while flow is the volume of gas delivered to the burner. Even when adequate pressure is available at the source, restrictions within the gas delivery system can result in insufficient flow at the fire feature. A fire pit can have a properly engineered burner, a reliable ignition system, and plenty of gas available at the source, yet still produce weak flames, inconsistent ignition, or nuisance shutdowns if the gas supply isn't delivering the correct pressure and volume to the appliance.
At HPC Fire Inspired, we believe knowledge is power. This Tech Talk is the first in a two-part series designed to educate consumers about gas pressure and gas flow, followed by a second article that builds on these principles to help users better understand how to identify and diagnose potential pressure and flow issues.
When Problems Arise:
When a fire feature does not perform as expected, the burner or ignition system is often the first component to be analyzed. However, the gas delivery system—including the supply, regulator, piping, connections, and other components—plays an equally vital role in achieving the intended flame appearance, reliable ignition, and consistent operation.
Knowing the warning signs of inadequate gas pressure or flow can help homeowners, designers, and installers pinpoint potential supply-side issues before replacing components that may be functioning properly. Recognizing these symptoms is an important first step in accurately diagnosing performance concerns as well as figuring out the proper next steps for further evaluation and corrective action.
In turn, the beauty of understanding the warning signs of gas pressure problems helps consumers and users save money and have continuous joy form their fire designs.
Gas Basics:
What Is Gas Pressure?
Gas pressure is the force that moves fuel through the piping system and into the fire feature. Outdoor gas appliances typically operate at relatively low pressures, which are measured in inches of water column, commonly abbreviated as WC. For many HPC Fire Inspired® outdoor appliances, general operating ranges include:
- Natural Gas: Approximately 3.5–7″ WC
- Propane: Approximately 8–11″ WC
The exact requirement depends on the specific appliance, burner, fuel type, and installation configuration. It is imperative to always follow the pressure requirements listed in the applicable HPC installation manual. It is crucial to have the correct pressure available at the appliance—not simply somewhere upstream in the gas system.
Common Symptoms of Low Gas Pressure
Low gas pressure—or insufficient gas delivery—is one potential cause of poor fire pit performance. The symptoms may vary depending on the burner, ignition system, fuel type, and installation.
Symptoms:
- Weak Flame Height
- Small or Weak Pilot Flame
- Delayed Ignition
- Uneven Flame Distribution
- Flame Dropout
- Performance Changes When Other Appliances Operate
A fire feature may operate normally when it is the only gas appliance in use, yet experience reduced or inconsistent flame performance when additional appliances are operating. For example, flame height or stability may change when a gas grill, fireplace, pool heater, outdoor kitchen appliance, or another fire feature is activated. This can be an indication that the gas supply system does not have sufficient capacity to meet the combined BTU demand of all connected appliances. For this reason, a fire feature should always be evaluated as part of the complete gas system, with consideration given to the total demand of every connected appliance—not solely the BTU rating of the fire feature itself.
Common Causes of Low Gas Delivery:
Low pressure at the fire feature does not automatically mean the utility or propane supplier is providing inadequate pressure. Problems can develop anywhere between the gas source and the appliance.
- Undersized Gas Lines
- Excessive Run Length
- Multiple Appliances on One System
Proper flame performance depends on the correct relationship between fuel type, gas pressure, gas flow, burner design, orifice sizing, and fire media.
Common Causes For Excessive Gas Pressure:
Too little pressure is not the only concern. High gas pressure does not automatically produce a better flame.
Excessive gas pressure may result in:
- Extremely tall flames
- Aggressive or unstable flame behavior
- Flame lifting or "blow-off"
- Excessive burner noise
- Humming or chattering gas valves
- Jet-engine-like sounds
- Damage to gas valves or other components
The Importance of the Regulator:
The regulator helps control gas pressure and maintain the supply required by the appliance. A regulator must be capable of supporting the total BTU demand of the system. Matching a regulator only to the fire pit burner may not be sufficient when multiple appliances share the same gas supply.
Regulator performance may also be affected by:
- Incorrect sizing
- Improper installation
- Moisture intrusion
- Contamination
- Excessive heat exposure
- Damage or wear
Regulators should only be installed and evaluated following appliance instructions, applicable fuel-gas codes, and local requirements. A qualified professional should only adjust gas pressure and regulator settings.
When Is Gas Pressure The Culprit?
Gas pressure or flow should become part of the troubleshooting process when a fire feature exhibits one or more of the following conditions:
- Flames are weaker than expected
- The pilot flame is small or unstable
- Delayed Ignition
- The burner shuts down unexpectedly
- Flame height changes when another appliance operates
- The fire feature recently changed location
- New appliances were added to the gas system
- A regulator or gas line was recently replaced
- The appliance produces unusually tall or aggressive flames
- The burner or gas valve makes abnormal sounds
These symptoms do not prove that gas pressure is the cause; however, they are indicative that the gas delivery system requires closer evaluation.
Do not Assume the Burner Has Failed:
One of the most common troubleshooting mistakes is replacing the burner before evaluating the gas supply. A burner may appear to be underperforming when the actual root of the problem is upstream.
Before replacing components, qualified technicians should consider these factors:
- Was another appliance added to the system?
- Was the gas line modified?
- Was the fire feature relocated?
- Was a propane tank or regulator replaced?
- Did the problem begin after construction was completed?
- Did the flame pattern change after new media was installed?
- Has the appliance been exposed to debris, moisture, or flooding?
When an outdoor gas fire feature is not performing as expected, the burner or ignition system should not automatically be assumed to be the source of the problem. First, consider the role Gas pressure and flow may be playing whenever flame performance or ignition changes.
Weak flames, reduced pilot flames, delayed ignition, uneven flame distribution, flame dropout, unusual burner noise, or changes in performance when other gas appliances are operating can all be indicators of a potential gas supply issue. The key is to recognize these symptoms; then further investigate the underlying cause.
Proper diagnosis requires appropriate testing and evaluation. Gas piping, regulators, valves, and burner components should only be inspected, adjusted, or modified by qualified professionals in accordance with applicable requirements.
Recognizing the symptoms is only the first step. In Part 2 of this series, we will move from identifying potential gas pressure and flow concerns to understanding how they are properly diagnosed. Our experts will examine pressure testing, operating pressure, regulator evaluation, gas line sizing, and burner inspection to help provide a more complete understanding of gas system performance. Follow HPC Fire Inspired as we continue to share the knowledge that helps professionals and consumers make informed decisions and enjoy reliable fire feature performance for years to come.
