Directions To Convert Weber BBQ Grills To NG or LP Fuel.

by grillrepair on March 29, 2014

Weber Barbecue Grills Can Be Converted To Natural Gas or to Liquid Propane Fuel For Cooking.

Although Weber does not permit gas conversions any longer the policy does not make the process any less simple than it has always been.

 

weber barbecue grill at majestic grill parts

American Made Weber Models manufactured before 2007 have the ability to stay in use for multiple decades with minimal replacements.

 

We rescued this old Weber barbecue grill.   A client purchased a new Weber barbecue and asked us to dispose of this old model.

Our work ethics are very strict so please note we tried vehemently to dissuade the client from buying a new model instead of repairing this old model.  A 20 year old Weber is worth 10 of the new barbecues being sold with the Weber name on them today.

Neither here not there….

We go get requests for assistance with Weber barbecue grill gas conversions.  We get these requests because we know gas barbecue repair technology very well with many, many years of experience — and because Weber made all their dealers sign a legal contract agreeing not to convert fuel type in any Weber models.

Which is nuts!  Even as a Weber warranty service provider we and they are not permitted to perform a process as ridiculously simple as converting to natural gas or converting to propane.

NG or LP connection feeds gas to the manifold.

NG or LP connection feeds gas to the manifold but the amount fed into the burner is determined by the size of the hole in the orifice.

 

As we saw in the video above the control panel on the side of the old Spirit models and the Genesis Silver and Gold and Platinum A, B and C models can be removed and lifted away from the control valves very easily.  Once the control panel is out of the way we are looking at the gas line connected to the gas manifold connected to the control valves.

weber manifold valve orifice and burner venturi with air shutter

Control valves pull gas from the manifold. The tip of the valve is inserted into the burner venturi which has an air shutter acting as a carburetor.

 

The tip of the control valve is inserted into the burner.   The front of the burner is where the air adjustment acts like a carburetor mixing gas with oxygen as the valve sprays gas mixed with air into the Weber pipe burner.

We are going to need to slide the burner off the valve so we can access the orifice.  In order to slide the burner off the control valve we have two options.  However, the condition of the barbecue will usually choose one of these options for us.  If not you are lucky but the build up of grease and the breakdown of materials  usually decides this for us.

the gas orifice is screwed into the tip of the control valve and determines the BTU rating of the grill and fuel type.

the gas orifice is screwed into the tip of the control valve and determines the BTU rating of the grill and fuel type.

We can  go into the fire box with the cooking grates and flavorizer bars (Weber heat shield vaporizers) out of the way so the far left side bolts holding the pipe burners in place are accessible.  If the botls are not totally covered in cooking greases and years of sauces we can unscrew these bolts, lift the burner up from the far left corner and slide the burner away from the burner.

The other option is to below the gas manifold on the far right side.  Under the manifold are two flat steel support brackets holding the manifold pipe to the right side of the barbecue firebox.  In their intelligent foresight Weber attached these brackets with thumb-screws easily unscrewed to slide the entire manifold assembly off the burners.

Usually we do not need to completely remove the manifold but just need to loosen the manifold so it slides away enough to extract the valves from the burners.

Slide off the burner to access the gas orifice.

Slide off the burner to access the gas orifice.

Once the burner slides off the control valve on the Weber manifold we will see the very tip of the valve looks like a bolt with a hex-head. If we look closer we will also see there is a tiny hole in this bolt-head.  This is the gas orifice.

The gas orifice attaches to the valve and is inserted into the burner during normal barbecuing.

The diameter of the hole drilled in this orifice in the tip of each control valve is what determines the BTU rating of each burner and of the grill as a whole.

Natural gas has a larger mass and is often (at least partially) mixed with oxygen so a NG orifice will have a much larger hole in it than the same BTU rating in a LP orifice.

change the orifice on the weber control valve to convert fuel to LP or NG.

change the orifice on the weber control valve to convert fuel to LP or NG.

Every gas appliance is regulated for a particular pressure setting.  The amount of pressure allowed through the BBQ regulator will also affect the BTU’s in the grill.

Obviously right?

If we have one pound per square inch of water pressure in a half-inch garden hose we will have a different flow of water than the same garden hose with 10 pounds per square inch, right?!

Now if we’re converting from NG to LP we will remove the natural gas orifice and we install the propane orifice.

However, if we remove the LP orifice and install a natural gas orifice we have to consider our pressure.  LP is always coming from a tank.  Even if we do not have a tank under the Weber side shelf we will have a gas line attached to a large tank elsewhere.  LP is almost always regulated at 11″ so we use 11″ water column displacement (about 1/8 of one pound per square inch) when determining what size diameter to drill the orifice.

Natural gas comes from  the city or county pump station and usually the gas line sticking out in the backyard will already be regulated for a low-pressure appliance because the fire pits, gas fireplaces and barbecues that we would place outdoors all use low-pressure regulators.  However, if natural gas is mixed with oxygen then we will need a different amount of pressure at sea level in Miami than the NG line on top of Pike’s Peak.  Also if the natural gas line is regulated down to a low pressure but then needs to run 100 yards to the stub-out for the barbecue then we’ll need more pressure to push the low pressure down that line.

Essentially natural gas is considered “normal” regulated at 2″ and at 12″ and all points in-between.

The best thing to do in order to be able to drill our orifices and convert the barbecue is to install an appliance regulator onto the bottom gas connection on the Weber gas manifold pipe.  That way we can put a 4″ or a 2″ regulator on the manifold and even if the gas line is regulated at 9″ the appliance regulator will step the pressure down to 4″ as the gas flows into the manifold to feed to the valves which feeds gas to the Weber burners.

Converting a gas barbecue from one gas type to another involves replacing every orifice for each valve on the barbecue and then replacing the regulator so the LP orifices match the LP regulator or the NG orifices match the NG regulator.

Last thing to consider:

Liquid propane vaporizes (boils) in the propane tank so the gas (vaporized) propane  is all gas.  Natural gas will often be mixed with oxygen.  For that reason the air shutter at the tip of the Weber burner where the burner mounts onto the control valve is often closed.  In a natural gas grill the burner air shutters are often adjusted closed or close to closed.  This is done when there is already oxygen mixed with the Natural gas line and we do not require more air flow mixing with the gas as the valve sprays gas into the barbecue burner.

Liquid Propane vaporizes to a pure gas and has No Oxygen mixed until the gas sprays through the orifice into the burner.  For this reason the air shutter is an integral part of the barbecue burner functioning effectively.

If you convert a Weber barbecue — or any barbecue — from NG to LP you will almost always have to adjust the air shutter open.  Likewise, if you convert a Weber barbecue from LP to NG the air shutter will almost always have to be adjusted closed.

We have several videos about adjusting the air shutter at the venturi of the burner and how to do this safe and correctly for the best flame pattern.  Using the video above these other videos are available.  You can also find these blog posts on this blog site and you can always Contact:

Majestic Grill Parts

954-2-GRILL-2

954.247.4552

Service@Grill-Repair.com

www.facebook.com/grillrepair

 

 

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