BBQ Control Valve Spiders: Manifold, Valve, Orifice, Burner Configuration.

by grillrepair on December 6, 2012

Spiders and bugs can impede gas flow in barbecue grill controls.

Although this is not a very common issue the urban-myth value and the strangeness of the occurrence means this gets talked about more often than it happens.  However, it is possible for a small spider or a small bug to stop gas flow or seriously shift gas flow patterns or  limit gas flow to such an extent that we cannot use the barbecue grill.

how to check for bugs in barbecue orifice and valve

directions for cleaning spiders and bugs out of orifice and valve

When this happens the assembly of grill parts that take part in gas movement needs to be examined and cleaned.

Parts of the Grill.

The gas line comes into a barbecue and attaches to a manifold pipe.  There are as many different manifold pipes as there are barbecue models.  The basic function of the manifold is to  allow the gas to flow into a solid, safe pipe so the control valves have a reservoir to pull gas.  The control valves seal to the manifold in every barbecue grill.

Although it is true a particular valve is only capable of allowing so much gas through at any time the valve does not have a limit other than it’s own size.  Every gas valve will have a threaded tip for an orifice.  The orifice serves the same function as the jet in a carburetor by limiting the amount of gas that can pass into the burner at one time. 

Depending on the type of gas, BTU rating of the burner and the amount of pressure the gas is under the orifice has a proscribed hole in the center that will only allow a definitive amount of gas through at any time.  With liquid propane which has very dense mass the standard 12,000 BTU burner uses a tiny hole about the size of a pin-prick.

valve and orifice and burner coming together

cast iron burner fits onto orifice which fits into the valve which attaches to the manifold.

Gas comes through the gas hose to the manifold, into the valve where it passes through the orifice into the barbecue burner.  The part of the burner that fits onto the valve orifice is called the venturi tube. The burner venturi — images show all this –will have an opening to allow air to be pulled into the burner in order to mix air with the gas flowing through the orifice and become flammable.

All sorts of critters get interested in crawling around in a barbecue.  This is especially true of barbecues that are not clean because the drippings, marinades, dry rubs, grease and pieces of food are all very appetizing to most critters small enough to get into the barbecue.  Small insects, spiders and bugs can crawl into the burner air vent in the venturi tube and stay within the barbecue protected from larger animals that might eat them.  From within the burner a small enough bug can crawl into the hole in the orifice.

control valve and orifice from american outdoor grill by firemagic

AOG by Firemagic control valve and orifice showing area inside valve behind the orifice

Next time we use our barbecue grill the gas flows through and probably kills the bug but now the web, carcass, and anything else associated with this bugs life inside the grill is jammed into the orifice and valve.  We do not see this but we do see flames shooting out of the control panel where there should not be flames or we see very low gas flow when our gas line is fully pressurized and should be burning better.

Usually when a client calls us to request assistance they’ll tell me they heard all about the strange case of bugs living inside the orifice so they cleaned that out before calling for assistance.  Unfortunately this often means the customer removed the grill burner to get at the orifice and they stuck a pin or something into the orifices.  Usually this just compacts the impediment and does not clear the opening for gas flow.

What most clients will not realize intuitively is that the bug is not living in the small opening in the orifice.  They are living inside the control valve.

In the image above that a is picture and is not a drawing that is an American Outdoor Grill control valve.  The AOG is a basic high-end BBQ model made by Firemagic.  Note we have unscrewed the hood-style gas orifice off the control valve and note the tiny hole in the tip of the LP orifice.  Yes, tiny spiders and bugs can crawl through that tiny hole.

infrared grill instructions for valve, manifold, orifice and burner

Direction schematic shows control knob, control panel, manifold, valve, orifice, burner and ignition assembled inside barbecue grill.

With the orifice removed we can see there is a nice-sized cavity in the control valve just inside where the orifice would normally be.  This is where the animals will make their home.

In order to clear the gas flow it is necessary to remove the orifice and clean the inside of the control valve.  We can place a vacuum cleaner hose over the end of the valve and allow the air current created to slowly pull out any debris.  We can also use canned air like the compressed air we use to clean computer boards and keyboards but this has to be used at a sharp angle because it is possible for compressed air to push debris tighter into the creases of the ball valve inside the cavity covered by the orifice.

While the orifice is out of the valve the tip can we rinsed with water and it can be cleared with air.  The spiders or bug is not usually in the hole of the orifice but the hole should be cleaned out to ensure there is no remnant stuck in the opening.  We generally do not want to use a pin or other thin hard object because we do not want to stretch or shave the opening in the orifice.  The BTU of the barbecue burner is set by limiting the amount of gas that can pass through this orifice and the difference of several hundred BTUs is so slight as to be invisible to the eye.  This alteration could make a big difference to the heat the grill provides.

control valve to orifice to grill pipe burner schematic

spec shows control valve to orifice to burner general assembly

That is it!  That is how to check and clean the spiders and/or bugs that can get into the control valve orifice of a barbecue grill.

Usually when someone calls about uneven gas spraying or low pressure the spider is not the problem.  Check valve issues with the safety features of the LP gas tank are far more common.  Removing the burner for basic cleaning and then putting the burner back into the grill slightly not-parallel with the valve is a very common reason for poor gas flow also.

For more information or for specific questions Please contact Majestic Grill Parts at:

954.247.4552. (954-2-GRILL-2)








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