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Honeywell 7800 vs Fireye vs Siemens LMV: BMS Compared

Updated Oct 26, 2026 · InduQT engineering team · Product facts checked Oct 26, 2026

The short answer

The Honeywell 7800 Series and Fireye BurnerLogix are flame safeguard controls: they sequence the burner and supervise the flame, and fuel-air ratio is handled by a separate linkage or positioning system. Siemens LMV5 and LMV3 and Fireye Nexus NX6100 combine the flame safeguard with electronic linkageless fuel-air ratio control in one unit, with optional O2 trim and VSD control on the larger models. Pick a 7800 or BurnerLogix to replace an existing flame safeguard on a mechanically linked burner; pick LMV5 or Nexus when you want linkageless control and O2 trim on a new or retrofitted burner.

  • Honeywell 7800 Series stores up to 127 fault codes and displays the last 6; flame signal reads 0 to 5.0 Vdc with 1.25 Vdc the minimum acceptable.
  • Fireye BurnerLogix shows the last 10 lockouts with burner cycle and hours, and offers Modbus over RS-485 and a 4–20 mA flame signal output.
  • Siemens LMV5 keeps a lockout history of the last 9 lockouts and a fault history of the last 21 on the AZL5 display; LMV52 adds O2 trim with the PLL52 module and QGO20 sensor.
  • Fireye Nexus NX6100 integrates a flame safeguard with parallel positioning of up to 10 servo motors and built-in UV, UV self-check and IR detection.
  • Fireye has been part of Spectrum Safety Solutions (Sentinel Capital Partners) since Carrier sold its industrial fire business in July 2024.
Burner management systems compared (from each maker’s documentation, read 26 October 2026)
FeatureHoneywell 7800 SeriesFireye BurnerLogix / NexusSiemens LMV5 / LMV3
What it isFlame safeguard and burner sequencer (RM7800, RM7840 and others) with plug-in flame amplifierBurnerLogix Y: flame safeguard. Nexus NX6100: flame safeguard plus parallel positioning in one unitIntegrated burner control and electronic fuel-air ratio control in one unit
Flame detectionPlug-in amplifiers for rectification (flame rod or rectifying UV), infrared, UV and optical detectorsChassis per detector: UV, self-check UV (45UV5, 55UV5), auto-check IR (48PT2), flame rod (69ND1), integrated scannersLMV5: QRI2 IR, QRA7 UV, ionization (all continuous); QRA2/4/10 and QRB intermittent only. LMV37 (North America): QRA4, QRB or ionization
Self-checking optionsR7861A with C7061 self-check UV; R7886A dynamic self-check UV with C7076; Dynamic Ampli-Check amplifiers test themselves 12 times a minute45UV5 / 55UV5 shutter self-check UV; 48PT2 IR with Auto Check amplifierQRA7 UV and QRI2 IR with self-test; ionization for continuous operation
Fuel-air ratio controlNot included; pair with linkage or a separate ratio controller (Honeywell SLATE offers a fuel-air ratio module)BurnerLogix: not included (pair with Nexus PPC6000). NX6100: up to 10 servosLMV50/51: up to 4 actuators; LMV52: up to 6; LMV37: up to 2
VSD (fan speed) controlNot includedNX6100: two VSD outputs on the VSD card; PPC6000: optionalLMV5: VSD module; LMV37: VSD air fan control
O2 trimNot includedNX6100 and PPC6000: optional O2 trim interface (Fireye zirconia probe or third-party)LMV52 with PLL52 module and QGO20 oxygen sensor
Lockout / fault historyUp to 127 fault codes stored; last 6 displayedLast 10 lockouts with burner cycle and hours (BurnerLogix)LMV5: last 9 lockouts and last 21 faults
How codes are shownKeyboard Display Module: sequence status, timing, hold, lockout fault code with plain-text message; 2-line VFD or 4-line LCD2-line by 16-character OLED (BLV512) or LCD (BLL510) display with plain-text messages; smart LEDsAZL5 display: error code (C), diagnostic code (D), phase (P), start count, load and fuel, plus plain text
CommunicationsModbus RTU (integrated on current models or via S7810M module); Thermal IQ remote monitoringModbus RTU over RS-485; 4–20 mA flame signal outputModbus; eBus PC adapter for service software; LMV37 has a Modbus interface
Typical applicationsSingle-burner boilers, furnaces, ovens and kilns of any capacity; very large installed base for retrofitsPackaged boilers, makeup air, process burners; Nexus for larger boilers wanting linkageless controlForced-draft burners from OEMs; LMV3 for single-fuel medium burners, LMV5 for large dual-fuel burners

The options side by side

1Honeywell 7800 Series

Best for: Like-for-like replacement of an existing 7800 or R4140 flame safeguard on a burner with mechanical or separate ratio control.

The 7800 Series (RM7800, RM7840, RM7838, RM7890, EC78xx and others) is a microprocessor burner control for gas, oil or combination single burners of any capacity. It uses a plug-in flame amplifier matched to the detector and a purge card for purge timing. Honeywell lists UL, FM, CSA and CE approvals and SIL 3 capability, and says the 7800 uses existing Honeywell flame detectors for easy upgrades.

Strengths
  • Huge installed base; technicians and spare parts are easy to find.
  • Clear flame signal test jacks (0–5.0 Vdc) make checkout simple.
  • Plain-language lockout messages on the Keyboard Display Module.
Check before you buy
  • No fuel-air ratio, VSD or O2 trim control in the 7800 itself.
  • Several relay module, amplifier and purge card combinations exist; match the exact part numbers when replacing.

Maker’s page: Honeywell (Thermal Solutions)

2Fireye BurnerLogix and Nexus

Best for: Sites standardised on Fireye scanners, and boilers moving to linkageless control in steps.

BurnerLogix Y (YB110, YB230) is Fireye’s current flame safeguard, with plug-in programmer modules, a choice of flame amplifier chassis, valve proving and low gas pressure functions, and a 10-lockout history. Fireye also publishes a guide for using BurnerLogix as a replacement for the Honeywell 7800. The Nexus NX6100 combines a flame safeguard with parallel positioning in one 5 x 8.25 x 3.75 inch unit; the PPC6000 adds parallel positioning beside a BurnerLogix.

Strengths
  • Self-check UV (45UV5) and auto-check IR (48PT2) options for continuously fired burners.
  • Step-by-step path from a plain flame safeguard to full parallel positioning with O2 trim.
  • Learned IR flame thresholds on BurnerLogix adapt to the fuel.
Check before you buy
  • Non-self-checking UV scanners (UV1A and similar) are only for burners that cycle at least once every 12 hours, per Fireye.
  • Parent company changed in 2024; confirm your distributor relationship.

Maker’s page: Fireye (Spectrum Safety Solutions)

3Siemens LMV5 and LMV3

Best for: Burner OEMs and retrofits wanting integrated linkageless control with O2 trim on one platform.

The LMV5 (LMV50, LMV51, LMV52) combines burner management and electronic fuel-air ratio control with up to 4 actuators (LMV50/51) or 6 (LMV52), a VSD module, and on the LMV52 O2 trim using the PLL52 module and QGO20 sensor. The LMV37 is a single-fuel unit with up to 2 actuators, VSD air fan control and integrated gas valve proving. Commissioning is done through the AZL display or PC software.

Strengths
  • One device for sequencing, flame supervision, ratio control and O2 trim.
  • Detailed lockout record: error code, diagnostic code, phase, start count and load at the time of lockout.
  • LMV37 comes in 230 V (Europe) and 120 V (North America) versions.
Check before you buy
  • Setting ratio curves needs a combustion analyzer and a trained technician; incorrect settings can create dangerous firing conditions, as Siemens warns.
  • Parameter access is password-levelled; keep OEM parameter backups.

Maker’s page: Siemens Smart Infrastructure

Flame safeguard or integrated burner management?

A flame safeguard (Honeywell 7800, Fireye BurnerLogix or Flame-Monitor) runs the burner sequence: prove airflow and interlocks, purge, trial for ignition, prove flame, release to modulation, and shut down and lock out on a flame failure or interlock fault. Firing rate and fuel-air ratio come from somewhere else: a jackshaft with cams and linkages, or a separate parallel positioning controller.

An integrated system (Siemens LMV5 and LMV3, Fireye Nexus NX6100, Honeywell SLATE) adds electronic fuel-air ratio control. Each damper and fuel valve has its own actuator, the controller holds the ratio curve, and position feedback is checked continuously. This removes linkage slop and hysteresis, holds excess air tighter across the firing range, and makes O2 trim and fan VSDs practical.

Burner management systems are safety devices. Commissioning, ratio-curve setting and any change to purge, trial or flame failure response times must be done by qualified personnel to the manufacturer’s procedure and local code. Never bypass, jumper or disable a flame safeguard, limit or interlock.

Flame detection: what each supports

  • Flame rod (ionization or rectification): suits gas pilots and gas burners. Honeywell uses rectification amplifiers (R7847); Fireye BurnerLogix uses a flame rod chassis and the 69ND1 rod; Siemens LMV supports ionization for continuous operation.
  • UV scanners: see the UV in nearly all flames, but a standard UV tube can fail in a way that reads as flame. Fireye says its non-self-checking UV scanners must only be used on burners that cycle at least once every 12 hours.
  • Self-check UV: a shutter or pulsed tube proves the detector itself during firing. Options include Honeywell C7061 with R7861A and C7076 with R7886A, Fireye 45UV5 and 55UV5, and Siemens QRA7.
  • Infrared: sees the flicker of oil and luminous flames and ignores hot refractory if set up correctly. Options include Honeywell C7015/C7915 with R7848/R7852, Fireye 48PT2 with Auto Check, and Siemens QRI2.
  • Integrated scanners: Fireye supports its Phoenix and InSight scanners directly on BurnerLogix and Nexus.

For continuously fired boilers that run longer than 24 hours without cycling, choose self-checking UV, self-checking IR or flame rod, as each maker’s documentation directs.

Reading lockouts and first-out history

All three show a plain-text lockout reason, but they record different amounts of history. Before you reset, write down the code, the message and the burner phase, because a reset can clear the current indication even though the history keeps it.

Where to find the lockout record
ControlHistory depthWhat a lockout record shows
Honeywell 7800Up to 127 stored; last 6 shownFault code, message and sequence step (for example PURGE, PILOT IGN, MAIN IGN), plus diagnostic and history submenus (DI, Hn) and the optional Expanded Annunciator first-out (EA)
Fireye BurnerLogixLast 10 lockoutsLockout message, burner cycle count and burner hours at the lockout
Siemens LMV5Last 9 lockouts; last 21 faultsError code (C), diagnostic code (D), phase (P), start number, load and fuel, with plain-text description

For limit and interlock first-out, the 7800 can add an Expanded Annunciator; BurnerLogix pairs with the YZ300 annunciator; LMV5 reports the open safety loop or input directly. Our burner lockout vs flame failure article explains how to tell an ignition problem from a scanner or interlock problem.

Which fits your boiler

  • Replacing a failed 7800 on a linkage burner: stay with the 7800 (match relay module, amplifier and purge card), or use BurnerLogix with Fireye’s 7800 replacement guide if your site is standardised on Fireye.
  • New packaged boiler or burner retrofit with linkageless control: Siemens LMV5 or Fireye Nexus NX6100; both offer O2 trim and fan VSD. Choose the one your burner OEM and local service company support.
  • Small single-fuel forced-draft burner: Siemens LMV3 (LMV37) covers up to 2 actuators with gas valve proving and VSD fan control.
  • Plant-wide monitoring: all three offer Modbus; Honeywell adds Thermal IQ remote monitoring.

How we compared them

We read each maker’s current product pages and technical documents: Honeywell’s 7800 product page, RM7800/RM7840 installation instructions and 65-0109 amplifier data; Fireye’s BurnerLogix manual BL-1001 and Nexus product pages; Siemens’ LMV5 basic documentation CC1P7550en (June 2025), AZL5 user instructions and LMV37 data sheet CC1N7546en. Where a document is hosted by a distributor or OEM, we say so in the sources. We compare published features only and do not score the products. InduQT does not sell burner controls.

Frequently asked questions

Is Fireye BurnerLogix a direct replacement for the Honeywell 7800?

Not plug-for-plug, but Fireye publishes a replacement guide (TD-00-2-0300-0-003-A) and conversion guides for using BurnerLogix in place of a 7800. Wiring base, scanner and programmer selection must be checked for each burner and the system rechecked by a qualified technician.

What is a good flame signal on a Honeywell 7800?

Honeywell gives a 0 to 5.0 Vdc range at the amplifier test jacks with 1.25 Vdc as the minimum acceptable. A falling signal usually points to a dirty sight tube, scanner or flame rod, or to a combustion change.

What does linkageless mean on a burner?

Each fuel valve and air damper has its own actuator controlled by the burner management system, instead of one motor driving them through cams and linkages. The controller holds a fuel-air ratio curve and checks each actuator’s position continuously.

Do I need O2 trim?

O2 trim measures flue gas oxygen and fine-tunes the air setting to hold excess air low as fuel, air temperature and humidity change. It pays back best on larger boilers with long firing hours. Siemens LMV52 and Fireye Nexus support it; the Honeywell 7800 itself does not.

Should I reset a burner lockout repeatedly?

No. Read and record the lockout code first and fix the cause. Repeated resets on a flame failure can let fuel accumulate in the furnace. If the cause is not clear, call a qualified burner technician.

Which flame scanner should I use on a boiler that fires continuously?

Use a self-checking type: self-check UV, self-checking IR or a flame rod, as the control maker specifies. Fireye says its non-self-checking UV scanners are only for burners that cycle at least once every 12 hours, and Siemens limits several detector types to intermittent operation.

Who makes Fireye controls now?

Fireye is part of Spectrum Safety Solutions, formed when Sentinel Capital Partners bought Carrier’s industrial fire business in July 2024. Fireye is still based in Derry, New Hampshire.

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