Troubleshooting Common Burner Trips in Combustion Appliances

Trips Are a Symptom, Not a Root Cause — and What Operators Often Misunderstand

In your oil and gas operations, a burner trip (otherwise known as a nuisance trip or shutdown on Profire BMS controllers) is rarely the actual failure point. Many operators initially assume the BMS is malfunctioning, when it is actually performing exactly as designed. Instead of looking at a trip as a system failure, it should be viewed as a safety feature.

Burner trips protect personnel, equipment, and the process when conditions deviate from acceptable limits. Your burner management system (BMS), including monitors such as flame failure devices, detect unsafe conditions, and will initiate a controlled shutdown before the situation escalates.

While safety trips are often seen as production interruptions, dismissing them as isolated events can hide the real value these signals provide. Improper burner sizing—oversized or undersized for the application—can further amplify the frequency of trips if the system is not tuned to expected BTU demand.

Trips are the symptoms of upstream or systemic issues. A flame failure may be triggered by fluctuating fuel pressure, but the true root cause could be a slow-responding regulator, improperly sized burner, or inconsistent supply from a central utility system. Operators often stop investigating too early, overlooking pilot orifice blockages, air intake issues on natural draft systems, or misconfigured high/low gas pressure setpoints.

Similarly, a high stack temperature trip may appear as an over-firing issue, but scaling, fouling, or sudden changes in process flow often drive it. In many cases, these underlying conditions develop gradually and go unnoticed until the BMS detects an unsafe condition.

Industry standards such as NFPA 85, API 556, and CSA B149.3 are designed with this principle in mind. They assume that trips will occur, and emphasize a methodical investigation after a shutdown to understand why the trip happened. Misunderstood setpoints, such as high and low gas pressure alarms, are frequent sources of confusion during post-trip reviews.

Treating trips as diagnostic signals rather than nuisances will allow you to improve reliability, protect equipment, and maintain compliance.

Public safety research into combustion equipment incidents highlights loss of flame and ignition sequencing errors as common triggers. While the controller is often the first component to be blamed for a trip, the root cause frequently lies in process dynamics—such as fuel/air issues, or installation and maintenance factors. Safeguards exist to reduce the potential for explosion or fire, which could lead to property damage and loss of production.

Sometimes, the main flame is present, but misaligned sensors, flame rod placement, or environmental factors prevent reliable detection. This reinforces the need to investigate trips as indicators of underlying system behavior, rather than isolated hardware problems.

This guide covers common burner trips and offers troubleshooting tips to turn disruptions into opportunities for system optimization.

Flame Failure Trips — and Why They’re Often Misdiagnosed

Flame failure trips are among the most common reasons for burner shutdowns. While often perceived as a single sensor at fault, they actually reflect a complex interaction of multiple systems within the BMS, including fuel delivery, valve operation, and airflow. These trips occur when the BMS cannot confirm the presence of the main flame after fuel delivery through the safety shutoff valves—even in cases where the flame is present, but detection hardware cannot reliably sense it.

Confirmation may come from flame rods, UV scanners, or IR scanners, and are all critical to monitoring combustion. While flame rods are durable, the wiring, grounding, or alignment issues can cause false trips. Scanners are also prone to lens fouling, scratching, or wear over time.

The immediate issue is loss of a reliable flame signal, but root causes often lie upstream, including fuel delivery through valves, airflow imbalances, or permissive interlocks. Operators commonly stop investigating too soon, overlooking pilot or main orifice sizing, valve response, or proper air intake maintenance, especially in natural draft systems.

Framing flame failure as an interconnected system issue highlights the need to evaluate not only flame sensors, but also fuel valves, regulator response, pressure switches, airflow, and overall system dynamics.

Fuel Supply Instability

Flame failure often occurs due to fluctuations in fuel pressure or interruptions in fuel delivery, particularly during peak demand or rapid load changes. Even minor pressure variations—caused by undersized regulators, fast-acting valves, or sudden shifts in shared utility supply—can weaken the flame, reducing the signal received by the scanner.

Mechanical issues are often the culprit. Slow-closing or sticking gas safety shutoff valves, worn actuators, or liquid fuel pump cavitation can momentarily starve the main flame. Even though the BMS shows a permissive, these events usually reflect genuine transient fuel delivery issues, rather than device failure. Similarly, pressure switches that chatter near their setpoints can temporarily remove the fuel permissive. This may cause valves to close and re-open just long enough to extinguish the flame, producing what appears to be a “mystery” scanner trip.

Such behavior is most common in forced draft systems with small incremental fuel input changes but can also occur in natural draft systems with fast-acting control valves.

In facilities where multiple burners share a utility system, sudden load changes can impact burners elsewhere, causing brief flame instability. Pilot or main orifice blockages and gas composition variations—such as high inert gas content—can further destabilize combustion.

Takeaway: “mystery” scanner trips commonly trace back to transient fuel delivery or permissive behavior, not device failure.

Fuel-Air Ratio Imbalance

Proper fuel-air mixing is critical for stable combustion in fired equipment, especially during startup or rapid load changes with forced and natural draft burner systems.

Excess or insufficient combustion air, or delayed air supply during load changes, can cause flame lift, flicker, or momentary extinction. Environmental factors such as wind gusts, nearby exhaust systems, or stack effect changes can further destabilize the flame. A weak or lifted main flame may still be present, but misalignment with the flame rod or scanner’s field of view can reduce signal intensity, causing the BMS to register a trip despite ongoing combustion. This effect is especially pronounced during startup, when valves are sequencing and air dampers are still in motion.

Systems with slow-starting TCVs tend to experience fewer trips, as transient fuel-air imbalances are reduced. Fuel-air imbalance is a common issue in field troubleshooting, particularly during startup and load ramping. Natural draft systems without secondary air control are especially prone to this challenge.

Takeaway: flame signal can drop during startup/load changes even when combustion continues, due to transient fuel-air mismatch and sensor line-of-sight.

Draft and Airflow Variability

Natural draft systems are highly sensitive to environmental conditions, and configurations with large-diameter, short stacks are particularly prone to draft instability. Wind gusts, nearby exhaust fans, or sudden stack effect changes can displace the flame relative to the scanner’s line of sight. Installing secondary air control (airplates) on all natural draft systems can reduce this instability.

This displacement also affects flame rod engulfment. A rod no longer fully immersed in the main flame loses ionization signal quickly, and poor grounding or wiring issues can worsen detection failures, even when combustion is occurring. Even in forced draft systems, damper misalignment, fan performance fluctuations, VFD issues, or mechanical fan failures can reduce airflow to the burner.

Flame sensors are designed to tolerate normal variations, but when multiple factors combine—draft fluctuations, misaligned dampers, or environmental effects—trips can occur, acting as a protective measure, rather than indicating sensor failure.

Takeaway: airflow/draft variability can move the flame out of sensor “view” or reduce ionization, triggering protective trips without a true flameout.

Flame Detection Hardware Degradation

Reliable flame detection is critical. While flame rods themselves are long-lasting, the wiring, grounding, and mechanical mounting are frequent points of failure. Whether using optical scanners or flame rods, hardware degradation—such as fouled, scratched, or heat-stressed scanners—reduces the system’s tolerance to normal process variability.

Fouled lenses, aging UV scanners or IR sensors, or misaligned optics weaken scanner signals, while fouled insulators, cracked ceramics, or grounding issues compromise flame rod performance. Signal loss from these issues is often misinterpreted as actual flame failure.

Hardware with marginal signal output will trip at the first sign of flame instability, particularly during startup or transient load changes that would otherwise be within safe operating conditions. This underscores that the core issue is signal quality and integrity, not just equipment age, and that proper inspection and maintenance can significantly reduce nuisance trips.

Takeaway: marginal signal strength reduces tolerance to normal variability, so maintenance improves signal integrity and reduces nuisance trips.

Flame failure trips indicate the BMS is functioning correctly. Repeated trips usually signal instability in fuel delivery, valve actuation, permissive devices (like pressure switches), airflow control, or degraded flame detection hardware. Operators often misattribute these trips to burner tuning or BMS malfunction, but the true cause is upstream system instability, disrupting the verification chain and preventing the system from reliably confirming the main flame.

Pressure and Airflow Trips

Fuel pressure switches and airflow transmitters serve as critical safety interlocks, intentionally tripping the burner system to prevent unsafe or unstable combustion conditions. These trips occur when sensors detect fuel pressure above or below allowable limits, or when airflow proving devices fail to confirm adequate purge or combustion air, acting as essential safeguards within the system.

High and low fuel pressure trips often indicate upstream supply dynamics, slow or misadjusted regulators, or system design factors, rather than failures in the burner hardware itself.

Low Fuel Pressure Trips

Low-pressure trips are especially common during peak demand periods or rapid load changes. When transient pressure dips, it can momentarily starve the burner of gas pressure. These trips are usually initiated by low-pressure switches located upstream or downstream of the main fuel safety shutoff valves, with their placement directly affecting burner sensitivity to short-duration pressure drops.

Field audits often reveal that slow-responding regulators, narrow switch deadbands, or supply line friction create brief pressure dips sufficient to break the fuel permissive, even when average supply pressure appears acceptable. In liquid fuel systems, worn fuel pumps, suction restrictions, or cavitation can create similar transient instability during startup or load ramp conditions.

Example: In one facility, a line heater experienced repeated low-pressure trips during morning demand spikes. Investigation revealed that fuel regulators could not respond quickly enough to short-term supply fluctuations, temporarily starving the burner and triggering trips. Improving regulator response and adjusting pressure switch settings eliminated repeat trips without any changes to burner tuning.

Takeaway: low-pressure trips usually result from transient supply dips and permissive break behavior, strongly influenced by switch placement and regulator response.

High Fuel Pressure Trips

High-pressure trips frequently indicate upstream issues, such as sticking regulators, incorrect setpoints, or thermal expansion in the fuel supply system, rather than defects in the burner hardware itself. High-pressure switches or transmitters will activate if upstream regulators fail or drift out of calibration, which can destabilize downstream valve operation and compromise flame stability.

Trapped fuel expanding thermally between closed valves is another common contributor to high-pressure trips, especially in systems without pressure relief or proper bleed paths. Excess pressure can impact safety shutoff and control valves, where high differential pressure can cause unstable flow, valve chatter, or difficulty achieving proper light-off, potentially triggering a trip even when the flame is present. Fuel pushed beyond the valve’s intended flow range can destabilize the flame, prompting the BMS to initiate a protective shutdown.

Takeaway: high-pressure trips are commonly driven by regulator/setpoint problems or trapped-fuel thermal expansion that destabilizes valve behavior and flame stability.

Airflow Trips

Combustion and purge airflow proving verify that air delivery meets required safety limits, with trips indicating the BMS correctly prevents operation under insufficient airflow conditions. Combustion airflow proving relies on airflow switches, differential pressure transmitters, or fan-proving switches to confirm fan operation and adequate air velocity.

A faulty pressure transmitter can produce inaccurate readings, potentially causing unnecessary trips even when airflow is sufficient. Issues such as a VFD failing to reach set speed, a misaligned or frozen damper, or mechanical fan failure can trigger combustion airflow trips, even if the fan appears to be running normally.

Purge airflow proving ensures enough air volume to safely remove unburned fuel from the combustion chamber before ignition, preventing ignition under fuel-rich conditions. Monitored by pressure transmitters, these interlocks are designed not to protect the fan, but to ensure the BMS prevents ignition in fuel-rich conditions, avoiding potential catastrophic failure.

Purge trips are frequently caused by fouled filters, blocked intakes, or environmental factors such as ice buildup in ducting, highlighting the importance of regular maintenance. Field experience confirms that both combustion and purge airflow trips are critical safety measures, reflecting proper BMS operation rather than equipment failure. Electrical or mechanical issues, such as a broken pressure transmitter, can falsely indicate insufficient airflow and trigger trips, mimicking unsafe operating conditions.

Takeaway: airflow trips validate proving logic—root causes often involve transmitters, VFD/damper/fan performance, or restrictions in the air path, not “fan looks like it’s running.”

In all pressure and airflow trips, the BMS performs as designed, breaking permissives to prevent unsafe operation, with the root cause usually found in regulators, switches, or environmental conditions, rather than burner tuning.

Preventing repeat shutdowns requires identifying and addressing the underlying root causes, such as faulty regulators, misadjusted switches, or environmental and maintenance issues. Adjusting burner tuning alone will not resolve these problems, as the cause resides upstream in the fuel and air systems. Focusing on these specific components and system maintenance is critical to ensuring consistent boiler uptime.

Temperature and Process-Driven Trips

Trips caused by high stack or process fluid temperatures are frequently misinterpreted as over-firing or burner tuning problems, but they are most often protective responses to process variability, restricted heat transfer, or fouled surfaces.

These trips are triggered by temperature signals from thermocouples or RTDs, typically located in the stack, radiant section, convection section, or process outlet. The BMS and associated interlocks compare these readings to defined safety limits, initiating trips when temperatures exceed acceptable thresholds. These interlocks operate independently of the burner firing rate, so trips can occur even when the burner output remains constant.

Trips often indicate protective responses to process fluctuations, blocked heat transfer, or internal fouling, such as coking or scaling, that creates localized hot spots within the heater.

Internal Fouling and Restricted Heat Transfer

Scale, coke, and fouling inside the firebox or heat exchanger insulate surfaces, gradually reducing heat absorption, and causing stack temperature sensors to exceed safety limits even when firing rates remain constant.

AMPP (Materials Performance) discusses how fouling/heat-transfer restriction in fired heaters drives underperformance and symptoms such as elevated stack temperatures. Uneven fouling, especially in multi-pass heaters, can create localized hot spots that trigger protective trips before operators notice a decline in process heat transfer. These hot spots may push process outlet temperature sensors beyond safety limits, activating the BMS’s protective trip logic. This scenario is particularly prevalent in systems processing viscous or contaminated fluids, including glycol reboilers and crude preheaters.

Takeaway: fouling and heat-transfer restriction raise measured temperatures at constant firing rate, creating hot spots that trip before performance decline is obvious.

Process Supply Variability

Variations in feed composition, flow rate, or inlet temperature can push heater temperatures beyond safe limits, prompting trips even when burner demand remains unchanged.

For example, an upstream glycol reboiler experienced repeated high-temperature trips caused by batch transfer-induced flow fluctuations, which temporarily exceeded the heater’s heat absorption capacity despite steady burner operation. The trips occurred without any change to burner firing rate, underscoring that the BMS was responding to actual process conditions rather than burner settings.

Through careful monitoring of inlet and outlet temperatures and adjusting feed rates, operators restored heat balance and prevented repeated trips, demonstrating that burner tuning alone cannot resolve process-driven thermal issues.

Takeaway: process variability can exceed heat absorption capacity and trip temperature limits even with steady firing—monitor process temps/flow to restore balance.

Interaction with Fuel Supply

Temperature trips frequently interact with fuel supply dynamics, as transient low fuel pressure can alter flame shape and heat distribution, increasing measured stack temperatures. For example, a heater with insufficient fuel pressure during peak demand may register elevated stack temperatures even without an increase in total firing energy. This occurs because unstable combustion or delayed fuel delivery alters the flame’s shape and heat distribution, increasing radiant heat to the stack or convection section.

Attempts to compensate by raising firing rates or adjusting excess air may further increase measured temperatures and trigger additional trips without addressing the root cause in fuel delivery or process flow.

Takeaway: fuel-pressure instability can distort flame shape/heat distribution and elevate temperature readings—tuning changes may worsen trips without fixing supply.

Ultimately, temperature-driven trips confirm the system has surpassed safe thermal limits, reflecting proper BMS protection rather than burner failure. They indicate a protective response to upstream process, fuel, or mechanical conditions—not a failure of the control system itself. If repeated high-temperature trips affect uptime, the focus should shift beyond burner tuning toward fouling, process variability, or fuel delivery issues as likely root causes.

Addressing these underlying process or mechanical issues is essential to restore reliable operation and ensure the heater can safely handle the thermal load.

Post-Trip Investigation Approach

A thorough and methodical investigation minimizes downtime and eliminates repeat visits. Many repeat issues arise because investigations stop at the immediate trip point, rather than digging deeper to uncover the root cause within the permissive logic. This approach often overlooks critical upstream factors, such as regulator performance, airflow instability, or improper sensor placement.

We recommend a three-step approach that distinguishes the initiating fault from the BMS’s protective response, ensuring the trip is analyzed as a diagnostic signal, not a nuisance.

Takeaway: treat trips as diagnostic signals—separate first-out (initiating fault) from the BMS protective response using permissive logic.

1. BMS Analysis

Accurately identify the first-out trip by determining which permissive transitioned to false first, rather than focusing on the loudest or most recent alarm.

• Use BMS event logs, permissive logic, and safety sequencing to trace the root cause.
• Track gas valve closure confirmations, pressure switch status changes, and flame signal timestamps—including flame rod or scanner signals—as these often reveal the initiating event more reliably than summary alarms.

This disciplined log interpretation, rather than assumption-based troubleshooting, forms the foundation for effective root-cause analysis.

Takeaway: first-out identification and disciplined log interpretation are the foundation for root-cause analysis.

2. Trend Review

Examine key variables leading up to the trip, including fuel pressure, airflow, temperature, and draft.

• Distinguish between steady-state drift, indicating long-term wear or fouling, and transient events such as oscillations, short-lived fuel pressure dips, or sudden airflow changes.
• Correlate multiple variables on a shared time axis—for example, verify whether fuel pressure decay or airflow fluctuations preceded flame signal degradation.
• Confirm scan rates and resolution in BMS logs, as slow intervals can obscure short-duration events that actually trigger the trip.

This approach helps identify whether the trip was due to upstream supply dynamics, environmental factors, or sensor limitations.

Takeaway: trend correlation (with adequate scan rate/resolution) separates drift from transients and exposes the real initiating sequence.

3. Physical Inspection

Perform a detailed hands-on inspection of flame scanners, flame rods, regulators, dampers, and air paths, looking beyond basic wear or fouling.

• Confirm flame scanner alignment relative to the main flame and verify signal strength under stable firing conditions.
• Inspect flame rod connections and grounding to prevent phantom trips.
• Evaluate regulators and dampers for response speed, repeatability, and proper operation, not just visible damage.
• Check pressure switches, airflow switches, and temperature sensors for secure mounting, proper calibration, and protection from vibration, heat soak, or weather exposure.

Additionally, inspect air intakes, ducting, and flame arrestors for fouling or blockage—common sources of nuisance trips. Verify all components meet expected operational standards before returning the system to service.

Takeaway: verify alignment/signal integrity and response behavior (not just visible condition) across the fuel and air proving chain.

The Benefits of an Investigative Approach

This method aligns with burner management system standards such as NFPA 85, API 556, and CSA B149.3, which prioritize documented cause determination and verification of safety device functions. A thorough investigation paired with controlled restart procedures following an abnormal shutdown not only ensures compliance, but also accelerates resolution, reduces unnecessary maintenance, and prevents improper burner tuning adjustments.

Taking a systematic, data-driven approach like this prevents repeat trips and ensures long-term system integrity.

Practical Tools for Your Team

Burner trips are diagnostic opportunities. Proper investigation converts a shutdown into actionable insights about system performance, process stability, and equipment health. Facilities that adopt structured post-trip processes can improve uptime, extend equipment life, and maintain safe operations.

To support this, we’re offering a Post-Trip Investigation Worksheet, which guides your team through systematic analysis, from identifying the first-out trip to reviewing trends and performing physical inspections. Using this tool helps teams move from reactive troubleshooting to proactive reliability management.

Using Trips to Improve Reliability

Trips provide critical insights into how your system operates under real-world conditions. They serve as diagnostic signals that reveal upstream issues in fuel delivery, airflow, or control devices. By viewing trips as opportunities, rather than mere interruptions, operators can turn each event into actionable insights for preventive maintenance and optimized process control. Allowing operators to:

• Detect supply chain or process variability early—such as fuel composition swings, upstream flow changes, or transient feed-rate fluctuations—before these conditions compromise stable operation.
• Identify and address degraded sensors or instruments—like flame rods, UV/IR scanners, pressure switches, and airflow transmitters—proactively to reduce the risk of trips and unplanned downtime.
• Avoid unnecessary maintenance and operational disruptions by focusing corrective actions on verified root causes, rather than reacting to superficial alarm signals.
• Strengthen system uptime and reliability by applying structured post-trip analysis to optimize regulators, dampers, fuel delivery, and permissive sequencing.

Adopting this perspective transforms trips into actionable tools for continuous improvement. A disciplined approach—including BMS log analysis, trend review, and physical inspection—ensures that root causes are accurately identified, enhancing both safety and operational efficiency.

How Profire Supports Your System Performance

When repeated trips disrupt uptime or strain operational resources, Profire’s service and field applications teams provide rapid diagnostics and actionable recommendations. Our specialists analyze trip data, evaluate fuel delivery, airflow, instrument performance, and BMS configuration, and verify corrective actions. Work with us to resolve recurring issues, implement lasting reliability improvements, and ensure your fired equipment operates safely and consistently.

If your burner keeps tripping after troubleshooting, contact our Field Services team. Our experts will help resolve the issue and restore your system’s performance.