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Commercial Commercial Charbroiler: Uneven Heat Across The Grates — Causes & Fixes

Compiled by Resultex Media Group · Editorially reviewed · Last verified August 2026

Quick answer: Uneven heat side-to-side or front-to-back is most often a leveling or maintenance issue, not a broken part. Check that the unit is level in both directions, that the deflector/crumb tray (or water pan/lava rock) is clean and correctly installed, and that individual burner valves aren't set to very different positions. Charbroilers are designed with per-burner valves so you can intentionally run hot and cool zones — so first confirm the pattern isn't just your valve settings. If the unit is level and clean but heat is still uneven, the burners or their air-shutters need a technician.
Food safety: Uneven grates create cold spots where product can finish undercooked. Probe the thickest pieces from the cooler zones and verify FDA Food Code 3-401.11 internal temperatures before serving; move product to a hotter zone rather than assuming even doneness. Note: returning food to 41°F does not by itself make it safe. If the time/temperature history is unknown, segregate the product and follow your food-safety plan; the FDA Food Code’s time-as-a-public-health-control provisions require specific written procedures, and local health-department requirements may differ. When safety cannot be verified, discard it.

Check in this order (5-minute diagnostic)

Work top to bottom — the quickest, most-likely checks are first.

  1. Unit not level. Check the charbroiler for level front-to-back and side-to-side; an unlevel unit heats and drains unevenly.
  2. Deflector/crumb tray or water pan/lava rock dirty or wrong. A deflector tray with blocked holes, a missing/misinstalled crumb tray, an empty water pan, or unevenly spread lava rock all distort the heat pattern.
  3. Burner valves set to different positions. Compare each burner knob — a big difference between sections produces intentional but sometimes unexpected hot/cool zones.
  4. Improperly adjusted burners / air-shutters or fluctuating pressure. Unit is level and clean but heat is still uneven, or flames differ burner-to-burner — points to burner/air-shutter adjustment or fluctuating gas pressure.

Likely causes, checks & fixes

Likely causeHow to checkWhat to doWho
Unit not levelCheck the charbroiler for level front-to-back and side-to-side; an unlevel unit heats and drains unevenly.Adjust the leveling feet/legs until the unit is level in both directions; recheck any time the unit is moved.DIY-safe
Deflector/crumb tray or water pan/lava rock dirty or wrongA deflector tray with blocked holes, a missing/misinstalled crumb tray, an empty water pan, or unevenly spread lava rock all distort the heat pattern.Empty and clean the deflector and crumb trays when cool and reinstall correctly (deflector holes clear, rear hooks over the crumb-tray edge); keep the water pan filled; spread lava rock evenly.DIY-safe
Burner valves set to different positionsCompare each burner knob — a big difference between sections produces intentional but sometimes unexpected hot/cool zones.Set the burner valves to match if you want an even surface; use different settings only deliberately for searing vs. holding zones.DIY-safe
Improperly adjusted burners / air-shutters or fluctuating pressureUnit is level and clean but heat is still uneven, or flames differ burner-to-burner — points to burner/air-shutter adjustment or fluctuating gas pressure.Have a qualified gas technician adjust the burners/shutters and check for a clogged regulator vent or unstable gas pressure.Technician

Who can do it: DIY-safe owner-doable · Basic simple part swap · Technician refrigerant/gas/electrical — call a licensed pro.

How to do the safe fixes

Owner-doable procedures only. Anything on the "Technician" list above needs a licensed pro.

Light the standing gas pilots (radiant charbroiler) Basic
  1. Turn the main gas shut-off valve and all individual burner valves OFF and wait 5 minutes to clear any gas.
  2. Turn the main gas shut-off valve back ON.
  3. Pass the lit ignition source through the pilot access/sight hole in the front panel and light each pilot in turn (the flame end must reach the pilot inside the unit).
  4. Confirm each pilot holds a small, steady flame (a slight yellow tip is normal on a standing pilot); if a pilot won't stay lit, stop and see the 'pilot won't stay lit' section.
  5. Once all pilots are lit, turn the individual burner valves to MAX to light the burners, then adjust to the desired setting.
  6. If any burner fails to light, turn all burner valves and the main gas shut-off to OFF and contact an authorized service agency.

· Tools: Long fireplace/BBQ lighter or match holder (reach at least ~7" past the front panel), Flathead screwdriver (only if the manual calls for a pilot flame adjustment), Heat-resistant gloves · Source: Vulcan/Wolf VACB/ACB Installation & Operation Manual (lighting the gas pilot); Star Ultra-Max manual (pilot lighting - wait 5 minutes, light pilots, then burners)

Relight a safety-pilot / runner-tube model (e.g., MagiKitch'n -S) Basic
  1. Turn all burners OFF. If the pilot just went out, wait 5 minutes before relighting to let residual gas dissipate.
  2. Remove the top grid and, on radiant models, a radiant to reach the runner tube.
  3. Turn the shut-off valve to ON, then press and hold the reset (blue) button on the safety pilot valve and wait 15-30 seconds.
  4. With the reset button still held, light the runner tube; if it doesn't catch, wait a few seconds and try again (first light after connecting gas can take 1-2 minutes).
  5. Keep holding the reset button an additional 15-30 seconds, then release it — the runner tube should stay lit. If it goes out, repeat; if it fails after three attempts, contact an authorized service agent.
  6. Replace the radiant and top grid, then push and turn the individual burner valves to light the burners.

· Tools: Long ignition source, Heat-resistant gloves · Source: MagiKitch'n 600 Series Gas Broiler Installation-Operation-Maintenance manual (RMB/SMB -S models with safety pilot)

Clean the grates, radiants, and lava rock (safe daily/periodic cleaning) DIY-safe
  1. Scrape the top grates with a wire brush during and after service, cleaning the underside of the rods so grease keeps draining forward.
  2. When the unit is cool, remove the grates and radiants and clean away fat, grease, and food; soak grates in degreaser (overnight if heavily caked), rinse thoroughly, dry, and re-oil to prevent rust.
  3. Reinstall one radiant per burner (never run the unit without radiants).
  4. For lava-rock units, monthly remove the rock, soak it overnight so grease separates, clean the lava grates, drain, and replace the ~2" pieces about one layer thick (never exceed the manufacturer's rock limit).
  5. Empty and wash the water pan/tub, grease box, and crumb/deflector trays; keep deflector-tray holes clear and reinstall trays correctly.
  6. Do not scrape or poke the burners or their ports, and do not use a water jet on the unit.

· Tools: Wire grill brush and scraper, Heat-resistant gloves, Detergent/degreaser or approved commercial grate cleaner, Bucket (for lava-rock soak) · Source: Vulcan/Wolf VACB/ACB manual (cleaning grates, radiants, trays); Star Ultra-Max manual (grate/water pan/lava rock cleaning); MagiKitch'n 600 (daily cleaning and maintenance)

Keep burner ports and the burner area clear (what's owner-safe vs. technician-only) DIY-safe
  1. With the unit OFF and cool, remove the top grates and radiants (or lava rock) and brush away carbonized debris that has fallen onto and around the radiants/burner shields.
  2. Wipe the burner area free of loose crumbs and grease so debris isn't sitting where it can block combustion; keep the crumb/deflector tray clean and the air-inlet area at the bottom/front of the unit unobstructed.
  3. Do NOT run a brush, wire, or tool into the burner ports, and do not remove burners, orifices, or the air shutters to 'clean' them — port, orifice, and shutter cleaning on gas equipment is a qualified-technician task.
  4. If burners are burning unevenly, have visibly blocked ports, or produce yellow/lifting flames after this cleaning, call an authorized gas service agency rather than disassembling anything.

· Tools: Wire brush/scraper, Heat-resistant gloves · Source: Star Ultra-Max manual ('brush out carboned particles'); Vulcan/Wolf VACB/ACB manual (radiants/burners; burner and shutter adjustment by trained personnel; annual technician inspection)

Stop and call a qualified technician if:
Repair or replace? A gasket, coil cleaning, or a simple part is almost always worth fixing. Weigh replacement when the unit needs a compressor or sealed-system repair and is roughly 8–10+ years old, or when repeated service calls approach the cost of a new unit. Compare current commercial charbroilers →

Related commercial charbroiler problems

Frequently asked questions

Why is my commercial charbroiler uneven heat across the grates?

Uneven heat side-to-side or front-to-back is most often a leveling or maintenance issue, not a broken part. Check that the unit is level in both directions, that the deflector/crumb tray (or water pan/lava rock) is clean and correctly installed, and that individual burner valves aren't set to very different positions. Charbroilers are designed with per-burner valves so you can intentionally run hot and cool zones — so first confirm the pattern isn't just your valve settings. If the unit is level and clean but heat is still uneven, the burners or their air-shutters need a technician.

When should I call a technician instead of fixing it myself?

Call a licensed technician for anything involving the sealed system, refrigerant, gas, or high-voltage wiring — for example: Improperly adjusted burners / air-shutters or fluctuating pressure. These are diagnostic-only for an operator.

Is it worth repairing or replacing?

Simple fixes (gaskets, coil cleaning, a single part) are worth repairing. Consider replacing when it needs a compressor or sealed-system repair and is 8–10+ years old, or when repeat service calls near the price of a new unit.

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