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Natural gas range & oven appliance (C) Daniel Friedman How to Convert a Heating Appliance from LP to Natural Gas
or from Natural Gas to Propane

  • GAS APPLIANCE CONVERT LP-NATURAL GAS - CONTENTS: How to change over from liquid petroleum gas (LP or bottled gas) to natural (piped-in) gas for gas fired appliances in a building. Advice for changing from LP gas to Natural gas in a building. Advice for converting between Natural gas and LP gas in a building. LP gas and Natural Gas conversion procedures & safety warnings
  • POST a QUESTION or READ FAQs about gas fuel conversions: LP or "bottled gas" to piped-in natural gas service
  • REFERENCES
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LP to Natural Gas conversions or Natural Gas to LP fuel conversion procedures:

This article explains the procedure for converting from LP gas or "bottled gas" to natural gas or "piped in gas" at a building.



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How to Convert a Gas Appliance From Natural Gas to Propane (or vice versa)

Bosch NGM8065UC gas cooktop conversion from natural gas to LP gas(C) Daniel FriedmanWatch out: Most manufacturers require that installation and fuel conversions shall be performed by a trained and qualified service technician. The technician should be sure to correctly identify the model number of your gas appliance so that s/he can follow the correct details of the manufacturer's instructions.

[Click to enlarge any image]

Article Contents

Five Steps in Converting a Gas Fueled Appliance From Natural Gas to Propane or LPG

LP gas conversion sticker applied to the converted gas appliance (C) Daniel Friedman

To change a gas fired appliance of any sort between LPG and Natural Gas fuel there are at least all of these fuel system changes that are ** required ** in the appliance:

  1. The gas supply pressure to the appliance (at it's shutoff, for example and thus ahead of the appliance's own regulator) must be regulated by a regulator at the building LPG or natural gas supply and must be within the range specified by the manufacturer
  2. The gas regulator at or in the appliance must be switched to the appropriate fuel: LPG or natural gas. Most appliance gas regulators can be converted in the field. For example in a Bosch unit I am working on the instructions have you remove a cap and invert a component inside the regulator, depending on which fuel you are using.
    See CONVERT the GAS REGULATOR
  3. The gas metering orifices or jets are changed at each burner in the appliance. Natural gas and LP gas do not use the same orifice sizes to achieve the appliance's designed BTU rate at the burner(s). Just changing pressure won't do it and is dangerous. The manufacturer may refer to these parts as "spuds" or "orifices" or "metering jets".
    See CONVERT the GAS ORIFICES
  4. The air mix at the gas controls at the appliance is changed to the appropriate rate for the fuel. For example in a Bosch gas range top that is delivered ready for natural gas, to convert to LP gas the instructions require the installer to rotate an adjustment screw (gently to a closed position in the case of this appliance) found at each of the individual burner controls on the appliance.
    See CONVERT the BURNER CONTROLS or AIR SHUTTER

    Some appliances such as a gas range that includes both a cook top and an oven will also require additional changes and adjustments at the oven.
    See CONVERT OVEN BURNER & THERMOSTAT
  5. Safety checks for gas leaks & proper appliance adjustment and operation

The gas appliance conversion kit manufacturer will provide a sticker indicating that the appliance has been converted - in this case from natural gas (as shipped from the factory) to ready for use with LP gas (propane). Be sure that that identifying sticker is affixed next to the appliance model and serial number data tag.

These steps only describe the conversion of fuel between natural gas and propane for a gas appliance. A separate sequence of gas cooktop or gas appliance steps is provided in a separate article series beginning
at GAS COOKTOP INSTALLATION.

Watch out: Converting a gas appliance is dangerous if not done correctly and in accordance with the manufacturer's instructions. Here are two typical manufacturer's gas conversion kit warning notices

This conversion kit shall be installed by a qualified service agency in accordance with the manufacturer’s instructions and all applicable codes and requirements of the authority having jurisdiction. If the information in these instructions is not followed exactly, a fire, explosion, or production of carbon monoxide may result, causing property damage, personal injury, or loss of life. The qualified service agency is responsible for the proper installation of this kit. The installation is not proper and complete until the operation of the converted appliance is checked as specified in the manufacturer’s instructions supplied with the kit. - Whirlpool corporation citation below 

This conversion kit must be installed by a qualified installer or service technician in accordance with these instructions. Installation must conform with local codes, or in their absence, with the latest edition of the National Fuel Gas Code, ANSI Z223.1. Failure to follow instructions could result in serious injury or property damage. The qualified agency performing this work assumes responsibility for this conversion. - Rheem conversion instructions - Natural Gas to LP Gas, citation below

If you are not sure whether your building and its appliances are served by LP gas (bottled gas or liquid petroleum gas) or by natural gas (piped-in gas), see the descriptions of each of these types of heating fuel
at GAS PIPING, VALVES, CONTROLS.

Tools Needed for Gas Cooktop Gas Orifice Spud Conversion Between Natural Gas & LP / Propane

Tools & supplies needed for converting a gas appliance fuel from natural gas to propane or propane to natural gas (C) Daniel Friedman

Tools listed by the manufacturer for converting between natural gas and LP gas or propane and for installing a gas cooktop or range will typically include a small-bladed screwdriver, a nut driver, and wrenches.

It's a rare installation job that goes like clockwork without encountering a surprise, as we will illustrate.

For example you may need a hammer and chisel if minor adjustments to wood obstructions intrude into the appliance opening, and you will certainly need both thread sealant designed for gas piping installation and a gas leak detector solution.

[Click to enlarge any image]

Tools for gas cooktop fuel conversion & installation into a countertop (C) Daniel Friedman

Above left are the manufacturer's instructions, slip joint pliers, a marker, a metric hex key set (more on this later), a small bladed screwdriver that fits the burner control knob air adjustment screws (more on this later), and a magnifying glass that let blind old guys read the stampings on the spuds or gas orifices.

Tools for gas cooktop fuel conversion & installation into a countertop (C) Daniel Friedman

You'll need a nut driver sized to match the spuds or orifices to be removed or installed along with a gas leak detector and thread sealant formulated for use on gas piping. As the manufacturers all insist that gas appliances should be installed only by a qualified technician (or by a licensed installer as is required by building regulations in some jurisdictions) we know you'll have all of these tools and supplies, but it's nice to have them at hand.

For example, the nut driver for modern gas appliance spuds may be a size that you didn't have, or you may have nut drivers only in inch-dimensions and you may need to buy one in metric dimensions to avoid damaging the brass orifice spud.

Tools for gas cooktop fuel conversion & installation into a countertop (C) Daniel Friedman

LP Gas <-> Natural Gas Appliance Regulator Conversion - Example

This topic is now
at CONVERT the GAS REGULATOR from Natural to Propane Gas

In an excerpt just below we illustrate removing the cap from the gas regulator for a Bosch gas cooktop in the NGM80 series. At below right the cap has been removed by unscrewing it from the regulator body. Close-up photos follow.

Bosh Gas Regulator for a gas cooktop (C) Daniel Friedman

Typically the conversion between fuels requires simply the rotation, inversion, or adjustment of parts already present on the gas appliance.

Bosch gas cooktop regulator fuel conversion from Natural Gas to LP Gas (C) Daniel Friedman

See CONVERT the GAS REGULATOR for details. from gas leaks.

Change the Gas Orifices (Spuds) to Convert between Natural Gas & LP Gas - Example

Use a magnifying glass to read spud orifice numbers when converting a gas cooktop between LPG and Natural gas (C) Daniel FriedmanSee CONVERT the GAS ORIFICES for complete details. A brief excerpt from that article is just below.

For most gas cooktops a threaded brass orifice or "spud" is used to meter gas at the proper flow rate at each burner. Gas flow rate, a combination of supply pressure and orifice diameter, determines the quantity of gas available at the individual burner and thus sets its BTU output rate or range.

The orifice diameter of these tiny little parts is different between natural gas and propane or LP gas. This means that you will need to change the orifice fittings to match the fuel you intend to use.

When converting an appliance from using a lower pressure natural gas fuel supply to a higher pressure LP or propane gas fuel supply, the new orifices will be smaller in diameter to accommodate the higher pressure of the fuel supply without releasing too much fuel too quickly.

Your appliance technician will have to select the proper orifices, remove existing orifices, and install the new ones in the right location following the conversion kit instructions from your appliance's manufacturer.

Watch out: leaving out this step or installing the wrong orifices is dangerous: the appliance won't work properly and you risk a fire or explosion. See CONVERT the GAS ORIFICES

How to Adjust the Top Burner Air Shutters or Air Supply to Convert between LP Gas and Natural Gas - Example

Some gas cook tops convert between Natural and LP gas at the Burners by turning or adjusting an air shutter (sketch at below left) while others require that you turn a screw adjustment inside or next to the burner control knob.

Example of converting a gas range oven regulator between LP gas and natural gas (C) InspectApedia

[Click to enlarge any image]

Here is an example of a convertible gas range burner top.

The valve hood (at left in the photo) is adjusted to an open or closed position depending on use with natural gas or LP gas.

Find and obtain the precise instructions from the manufacturer of your own appliance brand, model, and serial number in order to be safe.

LP to Natural Gas Regulator Conversion Example - (C) DJF

 

Air Adjustment Required at Gas Cooktop Burner Controls to Convert Between LPG and Natural Gas - Bosch Cooktop Example

Next we need to adjust the individual gas burner control air mix at the burner control knobs.

Turn the burner control knobs to the "OFF" position before proceeding.

Bosch gas cooktop burner control knobs before removal (C) Daniel Friedman

At above left we see the control knobs in place on the Bosch cooktop and at above right they've been removed and set aside. For Bosch gas cooktops there is a small air adjustment screw that needs to be set at each control knob position.

Bosch gas cooktop with gas burner control knobs removed (C) Daniel Friedman

Depending on the cooktop model the screw may be found inside the cooktop adjacent to a solid-stem control knob shaft or the screw may be (almost impossible to see) down in the center of a hollow-stem control knob shaft itself (shown in photos below).

A rubber gasket intended to keep crud out of the center of the control knob shaft will make it impossible to see the adjustment screw - you'll locate it by feeling gently inside the control knob shaft with your long small bladed screwdriver. You'll find that the screwdriver blade will insert about 1 1/2" into the hollow control knob stem, passing the rubber gasket, and finding the adjustment screw.

Gently turn the screwdriver to find the slot in the adjustment screw - it's a slot not a phillips-headed screw.

Gas cooktop (Bosch) burner control air adjustment screw opening (C) Daniel Friedman

Which way to turn the adjustment screw: the details of this air adjustment will vary by manufacturer. For the Bosch cooktop we are installing here the company says that to convert from natural gas to LPG (propane) you will need to turn the screw less than one full turn clockwise to a "closed" position. For our Bosch cooktop Bosch says you'll turn the screw just about 70 degrees clockwise (less than 1/4 of a turn) until the screw bottoms out. Your cooktop may have different specifications.

Bosch gas cooktop burner control air adjustment screw being turned (C) Daniel Friedman\

Watch out: Bosch warns that you must not use excessive force when turning the air adjustment screw or you can damage the assembly.

After setting all of the burner control air screws for the cooktop, replace the control knob and you've finished this step.

This sequence illustrates the conversion of a Bosch gas cooktop from natural gas to propane fuel. Other burner air shutter control adjustments for other cooktops and ranges are illustrated
at CONVERT the BURNER VALVES or AIR SHUTTER

When you have completed all of the modifications specified by the manufacturer to convert fuels you will typically have made three changes:

The gas regulator has been converted to LPG from natural gas (or vice versa)

The gas burner orifices or spuds have been changed out to insert orifices for the fuel being used (LPG in our case).

The gas burner air adjustment screw (or air adjustment shutter on some models) has been adjusted for the fuel being used (LPG in our case).

Gas Burner Flame Color Checks: How do we know if the gas regulator, orifices, and air supply are adjusted correctly?

What to Do if You Smell Gas Inside or Even Outside Near a Building

*** Immediate LP Gas or Natural Gas Safety Concerns:

From a safe location, call your gas company's emergency line and/or your fire department. The text provided here is a working draft and may be incomplete or inaccurate.

You should have your plumber test, repair, or replace any suspect gas controls or piping promptly. Replacement of a control itself should not involve significant expense. This repair should not be deferred. You should be sure that building occupants know if this or other unsafe conditions are present.

Inspect the Gas Flame for Proper Colour

Gas cooktop flame color check (C) Daniel Friedman

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The photo above shows the gas flame after a successful installation of our Bosch gas cooktop converted to burn propane. There is just a trace of yellow in the flame tips.

Comparing colours of gas flames: yellow = unhealthy, yellow tips = normal for LPG or propane, soft blue flame = normal for natural gas (C) Daniel Friedman adapted from Bosch (2014)

Our gas flame colour illustration shown immediately above, adapted from Bosch (2014),shows the properties of

More stuff to check when looking at the gas flame

Any of these indicate a possible malfunction of this equipment.

Watch out: Any of these LP gas , propane, or natural gas burner conditions is potentially very dangerous and needs prompt attention. You should have your utility company or service person check the appliance immediately.

More details and a longer list of gas burner or flame worries are
at GAS BURNER FLAME & NOISE DEFECTS

How to Adjust the Oven Burner & Thermostat to Convert between LP Gas and Natural Gas - Example

LP to Natural Gas Regulator Conversion Example - (C) DJF

Here is an example of a convertible gas range pressure regulator.

The oven burner hood is adjusted to an open (Natural Gas) or closed (Propane) position depending on the fuel.

Find and obtain the precise instructions from the manufacturer of your own appliance brand, model, and serial number in order to be safe.

Additional steps may be needed for your appliance, such as adjusting air mixture at the burner for the proper flame.

Watch out: failing to properly install, adjust, and vent a gas fired appliance can result in dangerous, even fatal carbon monoxide poisoning, gas leaks, a fire, or other dangerous conditions.

 

Natural gas and LP gas appliance compatibility

These two fuels are similar in that both are used to provide energy to home heating systems and other appliances but they have some different properties of weight, method of distribution, and chemistry. Most gas appliances are delivered already set up to use either natural gas or LP gas but not both.

Most gas appliances can be converted from one fuel to the other - what is involved may be simply changing gas metering orifices in the equipment (for example at the burners on a stove) or it may also be necessary to change or adjust a gas regulator located inside the appliance. Do not hook up an LP gas-ready appliance to a natural gas supply nor can you connect a natural-gas ready appliance to an LP gas supply without reviewing and acting on the manufacturer's instructions for converting the appliance from one fuel to the other.

Important Safety Warning: be sure that all gas-fired appliances in your building have been properly set up for the correct type of gas to be consumed.

Leaks at a hot water heater (C) Daniel FriedmanWatch out: General safety warning: improper installation and even improper inspection and testing methods involving natural or "LP" gas can involve dangerous conditions and risk fire or explosion. If you smell gas you should leave the building immediately and should do so without doing anything that could create a spark such as operating a light switch or telephone.

Do not connect an appliance set up for propane to a natural gas supply, and do not connect an appliance set up for burning natural gas to a propane gas supply without first making the required gas pressure and/or gas metering orifice adjustments. Making either of this mistakes can lead to gas leaks, fire, explosion, or potentially fatal carbon monoxide poisoning.

Virtually every modern gas fired appliance installation manual contains instructions for setting up the appliance to burn the proper fuel: LP gas (liquid propane from a tank installed at the property) or natural gas (piped in gas provided from a local gas utility company).

The pressure provided by natural gas is different from propane - adjustments will be needed at every gas fired appliance in the home.

Usually this means either an adjustment made at each gas burner at a metering device or in some cases a part actually has to be changed (an orifice through which the gas passes). On some appliances there may be a local gas regulator that also needs to be adjusted.

Where a gas burner metering device needs to be set properly for Natural Gas pressure or for LP gas pressure, the adjustment may be as simple as using a screwdriver or tool to turn the orifice from one position to another at each burner, or a part may need to be actually swapped out or exchanged. Appliance installation instructions will include sketches of where these parts are found as well as directions for how to set the metering device or regulator for the proper fuel.

Where is natural gas or LP gas pressure regulated for a gas fired appliance:

LP Gas Tanks (C) Daniel FriedmanFor LP Gas the pressure is regulated at the LP gas tank by a primary regulator and further pressure is matched to the requirements of the individual appliance by a regulator located at or in some cases inside the appliance such as a gas cooktop or gas clothes dryer or water heater.

At some buildings, particularly with long gas line runs there may also be an intermediate or building gas pressure regulator, particularly if the LP tank is distant from the building.

And for some appliances such as gas ranges and ovens, additional gas flow regulation is performed by a special metering orifice right at the gas burner.

We illustrate these gas regulators and orifices as well as fuel conversion between LP gas and natural gas in this article.

On many gas fired appliances the only adjustment that is required is to change or turn/adjust the gas metering orifice at the appliance burner.

Critical safety warnings about changing between gas fuel types: LP to or from Natural Gas

Watch out: Do not hook up an LP gas-ready appliance to a natural gas supply. Do not connect a natural-gas ready appliance to an LP gas supply. First you must read and act on the manufacturer's instructions for converting the appliance from one fuel to the other. It is virtually always the case that some equipment adjustments and changes are necessary to switch between natural gas and propane gas.

Testing for gas leaks after hookup is complete is another important safety step that should not be skipped.

The proper setup of gas burning appliances is very important since failure to set the appliance for the proper gas type can result in very dangerous, even fatal carbon monoxide production from improper combustion.

If your natural gas supplying company or plumber who is doing the hookup has not already offered to do so, ask them to go through the home identifying every gas-burning appliance, determine exactly what changes are needed, and make them before the appliances are again turned on with the new fuel supply.

Follow the appliance setup and gas fuel type adjustment instructions in the appliance installation manual provided by the manufacturer. If you cannot find the installation manual for your gas fired water heater, stove, furnace, boiler, or other gas fired appliance, make a note of the appliance name, model number, and serial number, and contact the manufacturer directly for these critical instructions.

The actual conversion from LP to or from Natural gas at the appliance itself is usually quite easy, but doing it properly is essential for safety.

Also see GAS REGULATORS for APPLIANCES

and GAS REGULATORS for LP TANKS.

Rainbow antique gas stove (C) Daniel Friedman

These two gas fuels are similar in that both are used to provide energy to home heating systems and other appliances but they have some different properties of operating gas pressure, weight, method of distribution, and chemistry.

Most gas appliances are delivered already set up to use either natural gas or LP gas but not both. However some older gas appliances such as the gas stove shown in our photo (above/left) may not be convertible between gas fuels.

Watch out: if the fuel at your building is not the fuel for which the gas fired appliance is set-up, the appliance must be converted to match the fuel you will be using. That conversion involves several steps and is not simply a pressure adjustment.

Most modern gas appliances can be converted from one fuel to the other - what is involved may be simply changing gas metering orifices in the equipment (for example at the burners on a stove) or it may also be necessary to change or adjust a gas regulator located inside the appliance.

For example as JR, an industry manager familiar with gas pressures pointed out, these two fuel gases operate at different pressures. In residential appliances

Gas appliance parts for sale (C) Daniel Friedman

The following additional examples show again where adjustments are required on a typical gas stove to convert between LP gas and Natural Gas. These examples are for a Glenwood Sunray gas range produced by the Glenwood Range Company. These adjustments should be made by a trained appliance installer or service technician.

Our photo (left) shows gas appliance parts and controls for sale at an open air market held on Tuesdays in San Miguel de Allende, Mexico. But as we warn below, installing or modifying parts on a gas appliance can be dangerous if you don't know what you are doing.

Watch out: these gas fuel type conversion examples are intended only for the purpose of general understanding of the type of changes that may be needed at a gas fired appliance.

Be sure to consult with the manufacturer or the installation and service manual to obtain and follow the exact gas fuel conversion steps for your particular gas appliance.

Otherwise your gas appliance is likely to be unsafe. To obtain the proper installation and service manual for your gas appliance you will need the product name, model number, code numbers/letters, serial number, and the date of installation or manufacture.

 

How to Install a Gas Cooktop into the Countertop & Connect Gas Piping & Electrical Power

This topic has been expanded & moved to GAS COOKTOP INSTALLATION

Watch out: If your gas cooktop came from the factory set-up for natural gas and your fuel source is propane (or vice versa) you should complete all of the gas conversion steps before proceeding to install the cooktop into the countertop.
See GAS APPLIANCE CONVERT LP-NATURAL GAS if you need to make this changeover.

Troubleshooting Converted Gas Appliances From LP to Natural Gas or Vice Versa

Reader Question: Can I use natural gas in a LPG oven,after boosting its pressure 2000 pa to 2800 pa and without changing its nozzles?

18 Feb 2015 Anonymous said:

Can I use natural gas in a LPG oven,after boosting its pressure 2000 pa to 2800 pa and without changing its nozzles?

and

Riaz said:
Can I use natural gas in a LPG oven,after boosting its pressure up to 2800 pa and without changing its nozzles?

These questions were originally posted at GAS PRESSURES LP vs NATURAL GAS

Reply: no.

Anon and Riaz:

Watch out: changing the gas supply pressure to a figure outside the standards specified by the manufacturer simply to try to switch between LPG and natural gas won't work and is dangerous.

To change a gas fired appliance of any sort between LPG and Natural Gas fuel there are at least all of these fuel system changes that are ** required ** in the appliance:

  1. The gas supply pressure to the appliance (at it's shutoff, for example and thus ahead of the appliance's own regulator) must be regulated by a regulator at the building LPG or natural gas supply and must be within the range specified by the manufacturer
  2. The gas regulator at or in the appliance must be switched to the appropriate fuel: LPG or natural gas. Most appliance gas regulators can be converted in the field. For example in a Bosch unit I am working on the instructions have you remove a cap and invert a component inside the regulator, depending on which fuel you are using.
  3. The gas metering orifices or jets are changed at each burner in the appliance. Natural gas and LP gas do not use the same orifice sizes to achieve the appliance's designed BTU rate at the burner(s). Just changing pressure won't do it and is dangerous.
  4. The air mix at the gas controls at the appliance is changed to the appropriate rate for the fuel. For example in a Bosch gas range top that is delivered ready for natural gas, to convert to LP gas the instructions require the installer to rotate an adjustment screw (gently to a closed position in the case of this appliance) found at each of the individual burner controls on the appliance.

In addition the manufacturers typically require that the conversion of a gas fueled appliance between LPG and Natural gas should be performed by a trained service technician who will also perform certain pressure and leak tests that are essential to avoid a fire or explosion.

And depending on where you live, such as in the U.S. in Massachusetts, the conversion of an appliance between LPG and Natural Gas is required by law to be performed by a trained and qualified service technician.

Example LP Gas Range Pressure Requirements

Finally, just a couple of data points as examples, again borrowing from one of Bosch's Gas Cooktop installation guides (NGM80 series using model NGM8065UC),

  1. The minimum gas supply pressure must be 1" water column (249 pa) above the manifold pressure printed on the appliance data plate
  2. The maximum gas supply pressure must not exceed 14" water column (3487 pa or 34.9 Millibars)
  3. The natural gas pressure ** for this specific appliance, yours will be different ** should be 7" water column (1744 pa) [ the instructions say 14.9 millibars which looks to me like a possible error as 14.9 millibars = about 6" of water column - ed.]
  4. The Propane or LP or LPG gas pressure ** for this specific appliance, yours will be different ** should be 11" water column (2740 pa or 17.4 millibars)

Range Cooktop Gas Conversion Citations

Reader Question: what can go wrong if wrong gas size orifices are installed?

(Apr 3, 2014) Mark Christopher said:

When converting a 90,000BTU furnace from Natural Gas to LP Gas (Propane), what can go wrong if the contractor installs the wrong size gas orifices? For example, if the proper LP Gas orifice is supposed to be size 1.15 (.0453 diam.) ..what can happen if he installed size 54 (.0550 diam.)? Specifically, can it cause excessive soot and eventually plug the heat exchanger?

This question was posted originally at HEATING SYSTEMS and also at the link cited just below.

Reply:

Mark
See GAS PRESSURES LP vs NATURAL GAS where in the FAQs we addressed this when that post was first seen.

Reader Question: converting an LP gas fired Kiln & Furnace to Natural Gas

4/26/2014 Ben said:

This Q&A originally appeared at GAS BTUH, CUBIC FEET & ENERGY

I have a kiln and furnace in a foundry. I have used LP gas at 15 lbs pressure through an initial 1/4 inch tubing into a 3/4 inch tube that divides into two 3/4 inch open pipes that serve as dual burners, when squirrel cage blowers are incorporated. These allow for the melting of bronze at 2200 degrees F.

I have converted to natural gas. With the same set-up and "standard pressure" (whatever that is?) adequate volume of gas and necessary btu is not being obtained. What should the pressure be to obtain comparable cubic feet of natural gas - compared to propane? I now can obtain the necessary btu when using a small hand torch and natural gas with atmospheric air.

But the volume is inadequate for the furnace/kiln combination. Your help shall be appreciated.

Reply:

Watch out: You should SHUT OFF YOUR EQUIPMENT IMMEDIATELY if you have not already done so. It is unsafe.

Ben, thanks for the interesting & important LP-NG conversion question.

We know that it's critical for both function and safety to get the pressures, orifices and metering devices, and equipment air mixtures correct when converting between LP gas and natural gas.

www.propane101.com - a website supported by propane dealers offers technical guidance, from which I quote:

Natural gas is a much lower pressure gas than propane and converting the appliance to one or the other gases requires that the differing pressure is compensated for. In other words, connecting a natural gas appliance to a propane piping system will result in appliance malfunction and possibly danger.

The reason for this is because natural gas orifices are larger than propane orifices strictly because of gas service pressure. In this case, the higher pressure gas flowing through a larger orifice will result in more gas through the burner and likely, more flame...an unnecessarily large flame.

Conversely, trying to use a propane appliance with natural gas will likely result in a very small flame or no burner flame at all because of the lower pressure gas and the smaller orifice. This is the underlying purpose of an appliance conversion from propane to natural gas or from natural gas to propane. Additionally, appliances cannot be converted from electricity to propane, or vice-versa.

Look for an LP to NG Conversion Label on the Equipment

If your equipment does not include a label indicating that it CAN be converted between fuels, you should not assume that such conversions will work and are safe. Generally a "conversion" changes both metering devices that meter the gas fuel and the air mixture adjustments as well. An improper air mixture adjustment, particularly in gas fired equipment, can produce fatal carbon monoxide gas.

What Components May Need to Be Changed Out or Adjusted on a Gas Fuel Conversion Job?

AO Smith water heater gas regulator (C) Daniel Friedman

To convert fuels in a gas fired appliance the propane experts I cited list more parts than you may realize that may need to be changed, including (besides what I've already listed) burners, burner tubes, regulators, orifices, safety controls, combustion air supply equipment, and venting of flue gases - equipment, chimneys, power vents, etc.

Furthermore, some of these must be adjusted or changed-out in concert with one another - in balance:
- the gas burner
- the air shutter (controls mix of combustion air with fuel)
- the gas metering devices (often jets or orifices)

Should you Just Replace the Heating Equipment rather than Convert?

The opinion of the propane fellows (and women) is that for some equipment that was not *designed* to be convertible between fuels, you'd be better off buying new equipment intended to work with the new fuel.

But before I'd consider such a step, I'd identify the brand and model of the foundry kiln and furnace you mentioned, find the manufacturer, and give them a call to ask advice. I'd be surprised if a gas fired equipment manufacturer produced products only for one fuel.

To review the science of LP and natural gas
see GAS BTUH, CUBIC FEET & ENERGY and also see Brinzea (2010) in our citations.

 

LP to Natural Gas or Natural Gas to LP Appliance Conversion References

Article Series Contents

...


Continue reading at GAS COOKTOP INSTALLATION or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see GAS REGULATOR ADJUSTMENT PROCEDURE

Or see GAS REGULATORS for APPLIANCES

Or see GAS PRESSURES LP vs NATURAL GAS

Suggested citation for this web page

GAS APPLIANCE CONVERT LP-NATURAL GAS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

INDEX to RELATED ARTICLES: ARTICLE INDEX to GAS APPLIANCES, PIPING, CONTROLS

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