Can You Convert Propane Back From Natural Gas? What to Know

If you recently moved or changed your home fuel setup, you might wonder if you can convert propane back from natural gas. The short answer is yes for most convertible household appliances. You can switch ranges, cooktops, and outdoor cookers back to liquid propane if you install the correct brass orifices and reset the pressure regulator.

Liquid propane delivers roughly 2,516 BTUs per cubic foot compared to only 1,030 BTUs for utility methane. That massive energy difference means each fuel operates under completely different line pressures and flow rates. Safety standards from the National Fire Protection Association outline strict hardware requirements for fuel conversions.

Understanding how these mechanical components interact ensures your reverse conversion stays safe, legal, and efficient.

Quick Answer: Can You Convert an Appliance Back From Natural Gas to Propane?

Yes, you can convert propane back from natural gas.

The appliance must support dual-fuel operation.

You need smaller brass burner orifices.

You must reset the gas pressure regulator to propane.

Always verify replacement parts match your exact model number.

Why Natural Gas and Propane Aren't Swappable (and Why That's Actually Good News)

Natural gas and liquid propane are not interchangeable fuels. Propane contains almost two and a half times more energy per cubic foot than natural gas. Because of this high energy density, propane appliances require tiny orifice holes to restrict fuel flow.

If you push propane through a wide natural gas jet, you get massive, uncontrollable flames and heavy soot.

Operating pressures differ significantly between the two fuel types. Natural gas flows at a lower pressure of 3.5 to 5.0 inches of water column. Propane requires a higher delivery pressure of 10.0 to 11.0 inches of water column.

Your appliance pressure regulator controls this incoming force. Inverting the regulator pin adjusts the internal spring tension to match the correct fuel delivery.

Air mixing ratios complete the combustion triangle. Propane needs roughly twenty-four parts air to one part gas for clean combustion. Natural gas only requires a ten-to-one air ratio.

Understanding these heat output measurements helps explain why hardware changes make fuel conversion fully reversible. Swapping the brass jets and setting the regulator restores factory propane performance.

The Convert-Back Decision Tree: Three Gates Every Appliance Must Pass

Before you dismantle any burner or purchase conversion hardware, run your appliance through three practical gates. If your equipment fails any single gate, the conversion process stops.

Gate 1: Does the Manufacturer List an NG-to-LP Reverse Kit for Your Model?

Start by locating your appliance data rating plate. You can usually find this metal badge inside the oven door frame, behind the lower drawer, or on the back panel of a grill. Check your exact model number against official manufacturer parts diagrams.

Brands like Whirlpool, GE, and Bosch clearly list whether an appliance supports dual-fuel conversion. If no reverse conversion kit exists in the catalog, the unit is single-fuel certified and cannot be modified legally.

Gate 2: Do You Still Have the Original LP Orifices?

When technicians convert an appliance from propane to natural gas, they often save the original brass spuds. Check for a small plastic parts bag taped to the rear chassis or tucked inside the manual packet. Having these original factory orifices makes the reverse process fast and inexpensive.

If those parts are lost, you must order an OEM replacement kit matched to your model. Never guess hole sizes or force generic fittings into your burner tubes.

Gate 3: Is the Gas Valve and Regulator Actually Convertible?

Inspect the appliance pressure regulator to verify it has a convertible cap. Convertible regulators feature an internal plunger marked with NAT and LP settings. Inverting this pin adjusts the spring pressure for liquid propane.

However, appliances like residential water heaters and standard home furnaces use sealed gas control valves. As of 2026, manufacturers build most residential water heaters with non-convertible gas trains that lack field adjustment options.

The Two Dead Ends: Hire a Licensed Fitter or Replace the Appliance

If your appliance has a sealed valve or lacks manufacturer support, do not attempt a DIY conversion. Forcing unapproved parts into a fixed gas valve creates an extreme fire risk. In many cases, buying a native propane replacement appliance costs less than hiring custom mechanical labor.

For complex residential furnaces, always consult a licensed gas technician to evaluate your options.

How to Convert Back to Propane: The Step-by-Step Workflow

Converting an appliance back to propane follows a straightforward mechanical workflow. Work slowly and verify every connection before opening the fuel supply.

1. Isolate the gas line and power. Turn the manual gas shutoff valve to the off position. Unplug the electrical power cord to disable the electronic spark igniters.
2. Disassemble the burner tops. Lift off the cooking grates, burner caps, and burner heads. This exposes the brass orifices threaded into the fuel manifold.
3. Replace every burner orifice. Use a 7mm socket or nut driver to remove the wide natural gas spuds. Thread the smaller LP orifices into the manifold by hand first. Snug them down gently with your tool, taking care not to strip the soft brass threads. Do not forget side burners on larger outdoor setups or internal oven bake jets.
4. Flip the pressure regulator pin. Unscrew the regulator cap with an adjustable wrench. Remove the internal plastic plunger, flip it so the LP marking points outward, and reinstall the cap firmly.
5. Reassemble and perform a leak check. Reinstall the burner heads and caps. Turn on the main gas supply line. Brush commercial gas leak detection solution onto every disturbed fitting. If expanding bubbles appear, turn off the gas and tighten the connection.
6. Calibrate the burner flames. Ignite the burners and observe the flame shape. If you see yellow tips, loosen the air shutter screw and slide the collar until you get crisp blue cones. Apply the LP conversion label over the old rating plate to complete the job.

The Mistakes That Cause Yellow Flames, Soot, and Carbon Monoxide

The most hazardous mistake is running propane through oversized natural gas orifices. Propane carries immense energy per unit of volume. A wide opening floods the combustion chamber with excess fuel, generating tall yellow flames.

This incomplete combustion produces thick black soot and rapidly spikes carbon monoxide levels indoors.

Skipping the regulator flip causes severe flame starvation. If you leave the regulator set to natural gas, manifold pressure remains at roughly 3.5 inches of water column. Propane requires 10 to 11 inches of pressure to pass through tiny orifice holes properly.

Leaving the pin on the NAT setting starves the burner, creating tiny, flickering flames that blow out under slight drafts.

Never attempt to solder and re-drill gas orifices at home. Precision fuel jets use microscopic drill gauges with strict manufacturing tolerances. Hand-drilling brass creates uneven edges and turbulent gas flow, ruining your air-fuel mixture.

Always source precision-machined brass replacements built specifically for your burner ratings.

Double-check every hidden burner before putting the appliance back into service. Homeowners often convert surface cooktops successfully but overlook lower bake burners or infrared broilers. Always consult the checking appliance rating labels on your unit to ensure every single valve receives its designated LP jet.

Safety, Code, and When to Hand This Job to a Licensed Gas Fitter

Most reverse conversions are legal to do yourself. The catch is doing them by the book. The National Fuel Gas Code, NFPA 54, treats a field conversion as a modification that must follow the manufacturer's listed instructions and use approved parts.

If your model has an official reverse kit and you install it correctly, you're within the rules in most jurisdictions. If you improvise with drilled or generic jets, you void the appliance's UL or ETL listing and usually the warranty too.

Permits matter for fixed piping. Converting a built-in range or furnace tied into house gas lines often requires a permit and a municipal inspection. A grill running off a portable 20 lb tank usually doesn't.

Call your local building department before you start if you're unsure.

Carbon monoxide is the real stake in all of this. The U.S. Consumer Product Safety Commission recommends CO alarms on every level of the home and outside sleeping areas.

Test yours right after any fuel conversion.

Call a licensed gas fitter instead of proceeding if any of these apply:

• The appliance failed Gate 3 with a sealed, non-convertible gas valve
• There's no reverse kit and no original LP orifices anywhere
• You smell gas at any point during or after the job
• The flame burns yellow, floats, or rolls out after the swap

Frequently Asked Questions

Does converting back to propane void my warranty?

Not if you follow the manufacturer's process. If the brand sells a reverse kit for your model and the installation matches its instructions, coverage stays intact. An unapproved conversion using drilled or generic orifices voids the warranty.

Some brands also require a licensed installer's sign-off, so keep the receipt and the conversion label.

Can I convert a water heater or furnace back to propane?

Usually no. Most residential water heaters use sealed gas control valves with no field conversion option, so the answer is no regardless of skill. Furnaces vary by model.

Some have documented LP kits and many don't. Check the rating plate and parts catalog first, then let a licensed technician confirm your options.

How much does a reverse conversion cost?

An OEM kit runs $20 to $120 for grills and cooktops, and $150 to $300 for full furnace kits. Professional labor adds $150 to $400 per visit. Always price a native propane appliance against that total before committing to a conversion on an older unit.

Can I just drill the NG orifices smaller myself?

No, and this shortcut causes the worst failures. Factory jets are machined to precise drill-gauge tolerances. Hand drilling leaves burrs and uneven openings that wreck the air-fuel mixture and spike carbon monoxide.

Buy precision brass spuds matched to your burner's BTU rating instead.

Will a grill converted back to LP work on a standard 20 lb tank again?

Yes, if it passed all three gates and got the correct orifices and regulator setting. A standard 20 lb DOT tank delivers the same pressure as a bulk propane supply. Before your first cookout, complete the proper burner seasoning and curing process so the grates and burners burn off factory residue cleanly.

The Final Call: Which Path Back to Propane Is Yours?

Your position in the decision tree decides everything. Here's the full map:

• Original LP orifices in hand, kit exists: This is the best case. A straightforward weekend DIY that takes most people one to two hours on a grill.
• Kit exists but the original parts are gone: Order the OEM kit by model number, wait for delivery, then run the same workflow above. Still DIY-friendly.
• Convertible valve but no listed kit: Stop here. This is licensed fitter territory, because matching orifices without factory documentation is guesswork with real consequences.
• Sealed valve or no manufacturer support: Don't force it. For grills, replacing the unit with a native propane model built for tank fuel usually costs less than custom fabrication and carries a fresh warranty.
• Any flame abnormality after conversion: Shut off the gas supply and call a pro. Yellow flames, soot, or flame lift mean the conversion isn't done, it's dangerous.

One rule overrides everything else in this guide. A conversion is finished only when every burner shows a crisp blue cone, every fitting passes the leak test, and the LP label covers the old rating plate. If any of those three checks fails, the job isn't done yet.