TEC G Sport Infrared Grill Fuel Conversion NG and LP Changed.

by grillrepair on December 1, 2013

A lot of the calls we receive are from customers looking for assistance converting a barbecue grill from natural gas to propane or from propane to natural gas.  A lot of manufacturers (and so-called manufacturers) will tell clients

TEC G sport infrared gas BBQ grill

This is the single burner infrared G-Sport model gas grill by TEC.

their appliances cannot be converted from one gas type to another but the truth is that a gas conversion is usually very simple.  Simple is not always the same as easy and simple does not mean there is not a chance to cause damage and physical harm and those manufacturers who claim the barbecue cannot be converted are usually lying because they fear a lawsuit.  As with any gas grill repair that involves touching, cleaning or changing parts that deliver gas, these repairs  should be performed by a licensed gas technician.  Most grill technicians will have started-off converting barbecue grills from one type of fuel to another because this is a simple task that will engender familiarization with the integral parts of the appliance.  For this example we’ll look at the G-Sport model by TEC,  Thermal Engineering Corporation who invented infrared grill burners.

TEC invented the infrared grill burner in its original manifestation of a stainless housing with a ceramic top tile covered with ports for pressurized flames.  Since so many competitors sprang-up quickly to copy this technology TEC did not have the normal 20 year development period defined by law.  Today TEC has miraculously survived the tough years of competition and has reinvented their grill models.  These new models are also a completely new design with very specific strengths and originality.  The G-Sport is one of these new models of infrared gas grills.

The TEC G-Sport has a single burner that is very large and mounts across the entire width of the fire box.  The heat generated by this burner magnifies as it refracts from inner structures around it and the heat builds up in this shallow fire box because there is a plate of glass on top of the firebox.  The sharp convex cooking grates sit on top of the glass to create a concave cooking surface.  This allows moisture to sit between the grids to be vaporized.  This removes one of the most common problems with outdoor cooking which is flare-ups from dripping greases, marinades, while basting and burning pieces of food that fall between the cooking grates.   The secondary strength of this new grid design is that the moisture hits the glass instead of sitting in the concave cooking grate which will cause rust of not cleaned regularly.

tec g sport stainless cooking grates with glass radiant shield

tec g sport stainless cooking grates with glass radiant shield.

In order to convert the TEC infrared grill for NG to LP or from LP to NG we will begin by removing the cooking grates and the glass.  The glass is going to be really filthy if you have not been cleaning it regularly.  The glass should be burned off and kept clean although most customers who contact us to buy replacement TEC glass have broken the glass while walking around carrying it or cleaning it incorrectly.  The glass should be sprayed with a powerful degreaser while resting in a even and level surface so weight can be evenly distributed.  Leave a rag on this level surface and place the glass there to be sprayed and then gently scrubbed with a green-side sponge pad.  I have also used a painting scraper with a razor blade to scrape the glass clean.

 

 

remove radiant glass in TEC g sport to get at the burner

remove radiant glass in TEC g sport to get at the burner

In the grill the glass is held down by a clip to the right side and the left side.  We do not have to unscrew the mounting bolts to remove the glass but move the glass carefully.    The glass radiant serves the purpose of building up heat from the burner and spreading radiant heat at the grilling surface.  Although no longer using the ceramic topped pressurized burners of the original infrared grills TEC grills will still heat above restaurant quality searing temperatures because of the design.   Note that barbecues and fireplaces and fire pits that use glass in their design will use a tempered glass which is a glass treated to withstand greater temperature and stress and to break in a safer way than a normal, untreated pane of glass.  However, glass is tempered by  applying great heat to the material.  A pane of glass is tempered by applying great amounts of heat.  In time this glass used in a gas grill, fire pit or fireplace has this process undone by the same application of intense heat.  Over time the glass is no longer tempered.  It will eventually need to be replaced but be very careful with the glass as it will become very fragile.

 

 

g sport tec burner

The stainless burner in the TEC G-Sport has 4 nuts holding it to the floor of the firebox. These are easily removed for uninstalling the burner.

Once the cooking grates and the radiant glass has been removed this is what we will see in the grill body.  The control valve is on the left side of the grill which is where the burner connects to the gas flow.  The burner inside the grill is mounted all the way across from left to right.  Fortunately there are only 4 nuts holding the burner to the grill.   Remove the nuts.  The bolts go through the body of the grill and will stay on the floor of the grill.  Remove the 4 nuts to uninstall the grill burner.

 

 

 

 

 

 

remove the g sport grill burner

remove the g sport grill burner by lifting the right side up while sliding the burner to the right so the venturi tube slides off the control valve.

The right side of the G-Sport burner rests on the floor of the grill but the left side of the burner continues through the walls of the barbecue grill so the venturi tube (the front of the burner where gas enters through the valve and mixes with air so it can burn) can attach to the control valve.    The control valve has a gas line coming to it so gas flows through the miniature ball valve of the control and into the burner.   At the tip of the valve where it enters the burner there is a small cap.  That small cap is the orifice.  The orifice has a small hole drilled in the tip so gas is restricted as it flows through the valve.  The gas valve orifice has to be changed when any appliance is converted from one gas type to an other gas type.

Natural gas is much larger by mass than liquid propane.  NG orifices will have a much larger hole in the tip of the orifice whereas an orifice designed for use with propane will be tiny by comparison.  Because of the difference in mass regulated pressure is also very different for NG and for LP.  The conversion of any barbecue consists of changing the orifices on every control valve and the regulator which is set for one gas type or another.

Remove the burner by lifting the right side of the burner and as we lift the burner we slide the burner to the right so the venturi tube slides off the valve and slides out of the holes in the side of the grill.  The burner will not lift straight out because the burner slides through the walls of the grill to fit onto the valve but we can lift and slide it gently to remove the burner without damaging the burner, the valve or the gas line connected to the valve.

Tec G Sport gas orifice seen through the burner hole

Tec G Sport gas orifice seen through the burner hole

Once the burner is removed if we were to stick a finger into the hole in the grill where the burner came out we will be touching the orifice.   This is clear from the image to the right where we can see into the hole in the fire box where the tip of the valve is covered by the orifice cap.   The orifice is a brass cap screwed onto the tip of the TEC control valve.  Natural gas will usually have a mixture of air whereas propane vaporizes from its liquid form to come through the valve a pure fuel.  Air mix adjustments are far more necessary on a LP burner than a NG burner.  The larger mass and the pre-mix with oxygen means the hole in the orifice used for Natural Gas is a lot bigger than the hole in an orifice for LP.       Looked at next to one another the hole drilled in an orifice for NG will appear huge next to an orifice hole drilled for LP — even though the BTU’s are exactly the same!

Lift burner out of infrared TEC grill to access orifice

Lift burner out of infrared TEC grill to access orifice from inside the barbecue box

When we are converting from LP to NG we can remove the orifice and drill the hole bigger for NG but we have to have the right tools and information for the hole to be drilled precise.   A hole drilled for 10,000 BTU’s and a hole drilled for 20,000 BTU’s will barely have an evident difference to an untrained eye.  An exact orifice drill bit has to be used and the bit is selected based on the amount of pressure passing through the regulator and the BTU’s  engineered to flow to that specific burner.  Because propane is always in a cylinder LP is always going to be set to regulate between 10-11 inches of water column displacement.  However, NG is considered “normal” regulated at 2″ and regulated at 10″ and all points in-between.  Although specific areas will require more pressure and more air-flow (high altitudes for instance will have thinner air and need more air mixed into less gas flow just as a long run of gas hose will need pressure stepped-up to keep the line pressurized to the appliance)  the regulator pressure is all the same to the grill so long as the orifice matches the regulator.  For instance if a specific sized opening allows 10,000 BTU’s to push into the burner when the regulator is pressurized at 2″ water column displacement then the same 10,000 BTU’s will use a much smaller orifice hole if the pressure is regulated at 10 inches.

If you are going to drill the orifice yourself then you have to determine the fuel used, pressure needed for the proper regulator and then drill the hole in the orifice based on a chart that shows the BTU’s compared with drilled-hole sizes and the amount of regulated pressure.

We do not necessarily need to see the orifice at the tip of the valve to replace it.  We can stick a finger in the hole and touch the orifice and we can just as easily insert a socket into the hole and feel around until we grab the orifice and unscrew it from the end of the control valve.  Depending on the task we remove the orifice either to drill the hole larger or to replace it completely.

Once the orifice is replaced or re-drilled and the orifice reattached to the threaded tip of the control valve we can put the rest of the grill back together.  Usually I’ll test for leaks first.  When usually testing for leaks we turn the gas On with the valve Off and then pour or spray soapy water until we locate the leak  blowing soapy bubbles.  However, since the replaced orifice is on the other side of the ball-valve control I will usually replace the burner and let it burn for a few minutes.  During the burn I will use a long lighter to click sparks around the control valve to see if there is any gas leaking to ignite.  If there is a leak at the orifice we can place a small smear of putty on the threads and replace the orifice.  Do not overtighten the orifice because the brass is soft and over-tightening can break off the tip of the orifice.

When there is no leak we replace the burner exactly the reverse of removing it.  Put the grill back together.

There is an ongoing argument about using a regulator on Natural Gas appliances.  If the gas pressure is regulated in th egas line before the gas line connection to the grill then a regulator will not do anything to change the pressure of the gas.  This is true and installing a NG regulator at (for instance) 4″ on a gas line that is already at 4″ seems superfluous.  However, without a gas technician and a manometer on site most of us cannot tell what amount of pressure has been regulated on the gas line.  Leaving an appliance regulator will tell us the pressure so we know exactly what to drill in the orifices.  Also if there is ever a problem with the gas line or a surge this appliance regulator will protect the gas pressure.

TEC G Sport Controls are on the left side of the infrared grill.

TEC G Sport Controls are on the left side of the infrared grill. Always seek the controls and the incoming gas line for fuel conversions.

Converting a barbecue grill from one gas type to another is as simple as changing the orifice(s) and changing the regulator.  On the TEC G-Sport the job is a little easier because there is only one orifice and the job is a little difficult because of the way the burner and valve are accessed.  All barbecues are essentially the same but some are more or less difficult to access the correct parts.

Finally, the determination of gas pressure in inches is because low-pressure appliances use a pressure below one pound per square inch.  We have all see water and gas gauged in pounds per inch expressed by 10 psi or 3 psi.  A low pressure appliance will normally use gas pressure at about 1/4 of one pound per square inch and this is measured by the amount of water-column displacement.  Any technician will have a manual manometer or electronic manometer to gauge the amount of pressure in a gas line.  The manual, mechanical manometer is a clear tube filled with water with a measuring tape printed on the clear tube so we can see how much of the water has been pushed out of the water tube.  When we talk about 11″ water column displacement this means LP will push 11″ out of the manometer at this amount of pressure in the gas line.  Liquid Propane and Natural Gas have very different mass and use different gas lines, fittings and regulators.

 

As always please contact us at Majestic Grill Parts with any questions and any requests for assistance.  Comments can be left below although we do delete all SPAM and report all SPAM to the proper internet governing authorities.

 

Please contact us for any assistance at:

954.247.4552.  954-2-GRILL-2

Service@Grill-Repair.com

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