How To Switch Natural Gas Stove To Propane: Complete Conversion Guide

Converting a natural gas stove to liquid propane requires swapping the surface and oven burner orifice spuds for smaller aperture sizes, reversing the appliance pressure regulator, and adjusting the burner air shutters. Because liquid propane operates at a significantly higher pressure (10 to 11 inches water column) and heat density than natural gas (3.5 to 5 inches water column), using unconverted orifices will create dangerous fuel-rich combustion, massive soot accumulation, and hazardous carbon monoxide emissions. Executing a systematic conversion ensures strict adherence to fuel safety standards, optimal thermal efficiency, and stable flame performance.

Pre-Conversion Requirements, Safety Protocols, and Tooling Checklist

Fuel gas conversions involve precise mechanical adjustments to high-pressure gas delivery components. Before attempting to convert any cooking appliance, you must verify that the specific range model is approved for dual-fuel conversion by checking the manufacturer serial plate. Modern residential stoves generally ship with an LP (Liquid Propane) conversion kit attached to the back panel or tucked near the pressure regulator, containing brass orifices stamped with metric aperture measurements and a color-coded identification chart.

Converting from natural gas (NG) to liquid propane (LP) requires an understanding of gas dynamics. Natural gas is supplied at lower pressure with an energy density of approximately 1,030 BTUs per cubic foot, whereas liquid propane delivers roughly 2,500 BTUs per cubic foot under higher delivery pressure. Consequently, LP orifice apertures are noticeably smaller than NG orifices for the exact same BTU output rating. Installing the incorrect orifice size causes severe over-firing or under-firing, invalidating appliance warranties and violating NFPA 54 (National Fuel Gas Code) safety mandates.

• Essential Tools & Materials Checklist:
  
  
  • Manufacturer-certified LP Conversion Kit (contains color-coded brass orifice spuds)
  • 7mm, 8mm, and 1/2-inch deep-well sockets or nut drivers
  • 1/4-inch drive ratchet with extensions
  • Adjustable open-end wrench (10-inch)
  • Precision flathead screwdriver (1/8-inch shaft for valve bypass screws)
  • Pipe thread sealant rated for LP gas (yellow PTFE tape or non-hardening gas pipe dope)
  • Commercial gas leak detector solution or non-corrosive bubble solution
  • Personal Protective Equipment (Cut-resistant gloves, safety eyewear)
• Mandatory Prerequisite Knowledge & Standards:
  
  
  • NFPA 54 / ANSI Z223.1 National Fuel Gas Code familiarity
  • Understanding Water Column (W.C.) pressure variance (3.5" W.C. NG vs 10" W.C. LP)
  • Knowledge of local plumbing and mechanical codes regarding flexible gas connectors
• Budget & Duration Benchmarks:
  
  
  • Estimated DIY Material Cost: $15 to $45 (if kit is missing; free if factory kit is attached)
  • Professional Labor Cost: $150 to $350
  • Required Execution Time: 60 to 90 minutes

Standardized Conversion Protocol for Ranges and Cooktops

Step 1: Power Disconnection and Main Fuel Isolation

Shut off the electrical supply to the range by unplugging the power cord from the wall receptacle or switching off the dedicated circuit breaker at the main breaker panel. Locate the manual gas shutoff valve installed on the rigid gas supply pipe behind or adjacent to the appliance. Turn the valve handle perpendicular to the gas line to completely cut off the gas flow. Disconnect the flexible stainless steel gas connector from the range using two wrenches—one holding the pressure regulator steady and the other unthreading the flare nut to prevent twisting the internal manifold piping.

Warning: Operating electrical components or ignition switches while gas is unsealed can ignite residual gas lingering in the lines. Always verify total gas isolation and electrical power disconnection before loosening any gas fittings.

Step 2: Converting the Main Gas Pressure Regulator

Locate the range's pressure regulator, typically situated at the lower rear of the appliance or accessible by removing the bottom warming drawer. Identify the hexagonal metal or plastic cap located on the top center of the regulator housing. Use an adjustable wrench to unscrew and remove this cap.

On the underside of the cap, you will find a spring-loaded plastic or brass pin stamped with markings designated "NAT" on one side and "LP" on the other. Carefully pull the pin off the cap stem, reverse its orientation so that the "LP" marking faces away from the cap (or points down toward the regulator body upon reinstallation, depending on the manufacturer design), and snap it back into place. Re-thread the cap onto the regulator housing and tighten securely using your wrench. Ensure the internal rubber gasket remains properly seated to prevent low-pressure gas leaks.

Pro-Tip: Some commercial-style ranges do not use a reversible pin. Instead, they require unscrewing the cap, turning it upside down, and re-screwing it, or replacing an internal spring entirely. Always reference the regulator stamping to ensure the word "LP" is visible after assembly.

Step 3: Swapping Cooktop Surface Burner Orifices

Remove the cast-iron cooktop grates, burner caps, and burner heads to expose the brass orifice spuds seated inside the center of each burner base. Using a deep-well nut driver (typically 7mm or 9/32-inch), turn each natural gas orifice counterclockwise to unthread it from the gas manifold tube. Take care not to drop the loose orifice into the burner housing cavity.

Cross-reference the stamped number or color ring on the new LP orifices with the orifice selection chart provided in your range conversion manual. Higher BTU burners (such as a 15,000 or 18,000 BTU power burner) require larger LP orifice openings than low-BTU simmer burners (5,000 BTU), but all LP orifices will be significantly smaller than their NG counterparts. Thread the correct LP orifice spud into each corresponding burner base by hand to prevent cross-threading. Tighten each orifice using your nut driver until snug; do not overtighten, as soft brass threads shear easily under excess torque.

+-------------------------------------------------------------------+ | Example Surface Burner Mapping (Varies by Manufacturer): | | - Power Burner (18,000 BTU NG -> 15,000 BTU LP): Orifice 0.99 mm | | - Standard Burner (9,500 BTU NG -> 8,500 BTU LP): Orifice 0.78 mm | | - Simmer Burner (5,000 BTU NG -> 4,000 BTU LP): Orifice 0.52 mm | +-------------------------------------------------------------------+

Step 4: Converting Oven Broil and Bake Burners

Access the lower bake burner by opening the oven door, removing the bottom panel mounting screws, and lifting out the floor plate along with the flame spreader shield. Locate the bake burner tube and its connection point to the rear gas valve.

For appliances with fixed orifices, unthread the natural gas orifice spud using a 1/2-inch open-end wrench or socket and replace it with the dedicated LP bake orifice included in your conversion kit. For older ranges with adjustable orifice hoods, use a 1/2-inch wrench to turn the hood clockwise (downward) roughly 1.5 to 2 full turns until it seats firmly against the internal LP pin. Do not force the hood past its stopping point, as over-tightening crushes the needle valve.

Repeat this exact procedure for the overhead broil burner if your model features an upper gas broil tube. Ensure the orifice fitting aligns straight with the burner inlet barrel to maintain smooth gas injection.

Step 5: Air Shutter Calibration and Primary Flame Adjustment

Gas burners require a balanced air-to-fuel ratio to achieve complete combustion. Locate the adjustable metallic air shutter sliding collar positioned at the entrance of the bake and broil burner tubes. Loosen the Phillips-head securing screw on the shutter collar.

For natural gas, air shutters are generally set relatively tight (roughly 1/8-inch open). For liquid propane, slide the shutter wide open to allow more primary air to mix with the denser propane gas—typically opening the slot to between 3/8-inch and 1/2-inch. Tighten the securing screw to lock the shutter position before testing.

Re-establish the gas connection by wrapping male pipe threads with gas-rated yellow PTFE tape or pipe dope, reattaching the flexible connector, and opening the main gas valve. Plug in the electrical cord. Ignite the bake and broil burners to inspect the flame pattern. A properly adjusted LP flame displays a clean, stable, inner blue cone measuring 1/2-inch to 3/4-inch with no yellow tipping or lifting off the burner ports.

Pro-Tip: Soft yellow tips indicate insufficient air entrainment (open the shutter wider). A noisy, roaring flame that lifts off the burner frame indicates excessive primary air (close the shutter slightly).

Step 6: Low Flame (Simmer Bypass Screw) Tuning and Leak Testing

To prevent burners from blowing out when turned down to the lowest setting, the valve bypass screws inside the control knobs must be adjusted for liquid propane's higher operating pressure. Pull off all cooktop control knobs to reveal the brass valve stems. Look down the hollow shaft of the valve stem or directly adjacent to the stem housing to locate the small, recessed slot-head bypass screw.

Light the corresponding surface burner and turn the control knob to the "LO" position. Insert a thin, flathead precision screwdriver into the valve stem to engage the bypass screw. Turn the screw clockwise until the flame decreases to a stable, minimal height (roughly 1/8-inch tall across all burner ports). Turn the knob quickly from "HI" to "LO" several times; if the flame extinguishes, turn the bypass screw counterclockwise slightly to increase fuel flow until the flame resists air drafts without lifting.

Perform a thorough leak detection test across all modified joints. Brush commercial gas leak solution or soapy water onto the pressure regulator cap, flex line connections, and burner valve fittings. Watch for expanding bubbles over a three-minute period. If bubbles form, immediately isolate the gas valve, depressurize the system, and reseal the leaking fitting.

Warning: Never use an open flame or match to check for gas leaks. Liquid propane is heavier than air and pools in low areas, creating an extreme explosion risk if exposed to an open flame.

Fuel Dynamics and Conversion Parameters

Post-Conversion Burner Diagnostics and Field Fixes

Scenario 1: Yellow, Sooty Flames on Cooktop Burners

• Root Cause: The natural gas brass orifice spuds were left in place, or an LP orifice with an aperture size too large for the burner's rated BTU output was installed, flooding the combustion zone with excess fuel.
• Actionable Fix: Shut off the gas, remove the burner caps, and confirm the metric aperture size stamped on the side of each brass orifice against the manufacturer's manual. Replace any incorrect orifices with smaller LP spuds. Clean off any accumulated black carbon soot from the igniter electrodes and burner heads using isopropyl alcohol and a soft nylon brush.

Scenario 2: Oven Burner Flame Lifts Off Ports or Produces Loud Roaring Noise

• Root Cause: Excessive primary air velocity caused by opening the air shutter collar too wide, which destabilizes the flame boundary along the burner rail.
• Actionable Fix: Access the oven bake or broil burner tube by removing the bottom cover panels. Loosen the air shutter securing screw and rotate the collar slightly toward the closed position in 1/16-inch increments. Re-test the burner ignition until the flame lays flat against the port holes with a solid, silent blue core.

Scenario 3: Burner Extinguishes Immediately When Turned to Simmer ("LO")

• Root Cause: The valve bypass screw was not adjusted during the conversion, causing the reduced natural gas bypass rate to deliver insufficient gas volume under higher LP pressures.
• Actionable Fix: Remove the control knob for the failing burner to access the internal bypass screw located down the valve stem axis. Turn the burner to "LO," insert a small flathead precision screwdriver, and rotate the screw counterclockwise slightly to increase the minimum low-gas channel volume until the flame stays lit reliably when toggling settings.

Scenario 4: Persistent Gas Odor Near Pressure Regulator After Conversion

• Root Cause: The pressure regulator cap gasket was pinched, misaligned, or omitted during the pin-reversing step, or the hex cap was not torqued down adequately to compress the seal.
• Actionable Fix: Turn off the main gas shutoff valve immediately and vent the area. Unscrew the regulator conversion cap, inspect the internal rubber O-ring or flat gasket for cracks or misalignment, apply a light coat of LP-compatible thread sealant to the metal cap threads if specified by the manufacturer, and re-torque the cap firmly. Perform a bubble solution leak test before restoring power.

Frequently Asked Questions

Can I convert any natural gas stove to liquid propane?

Most modern residential gas stoves are designed to be dual-fuel compatible and come with or support an LP conversion kit. However, you must check the serial dataplate or owner's manual to confirm "LP Conversion Approved" status. Attempting to convert an non-certified appliance invalidates safety listings and poses severe fire hazards.

What happens if you run a natural gas stove on propane without converting it?

Running an unconverted stove on propane forces high-pressure, energy-dense gas through overly large orifices, producing dangerously tall, uncontrolled yellow flames. This incomplete combustion generates massive amounts of sticky black carbon soot and lethal levels of odorless carbon monoxide gas within seconds.

How do I know which LP orifice goes to which burner?

LP conversion kits include orifices stamped with specific numbers indicating their hole diameter in millimeters (e.g., "0.72" or "89"). The range conversion instruction sheet provides a lookup table matching these stamped numbers or color-coded rings to the specific location of each burner (e.g., Left Front Power Burner vs. Right Rear Simmer Burner).

Do I need to change the gas hose when switching from natural gas to propane?

Yes, you should ensure the flexible stainless steel connector and any inline regulators are explicitly rated for liquid propane service. Additionally, if connecting to an external propane tank, a dedicated high-to-low pressure two-stage LP regulator must be installed at the supply tank to lower pressure down to 11 inches water column before reaching the appliance.

Is a professional technician required to convert a gas stove?

While experienced home mechanics can perform an LP conversion using standard tools, many legal jurisdictions and municipal plumbing codes require a licensed gas fitter or appliance technician to execute or inspect the conversion. Hiring a certified professional ensures compliance with local gas codes and validates home insurance policies.

Professional Gas Appliance Support & Verification

If you encounter persistent burner ignition issues or lack the specialized tools required to test gas line pressure accurately, consult a licensed plumbing and heating professional. Expert technician verification guarantees that your appliance conversion meets strict mechanical code standards and operates at maximum fuel efficiency.