We get a lot of calls for this particular problem. The barbecue grill rotisserie burner is the only infrared burner on a lot of barbecues and it is often the only burner that is not a part of the convection burners inside the fire box. The rotisserie burner valve is not the same valve used on the regular barbecue burners inside the firebox.
Typically the barbecue valve is a simple ball valve with an orifice attached to determine BTU capacity. The rotisserie burner will have what is called a safety valve because if the vertical position and ability for flames to be blown out.
There are a few different versions of the safety valve. The most common safety valve is the valve used on gas fireplaces that burner liquid propane gas. LP must have a pilot and the pilot is used to allow gas to keep flowing. Most people know the pilot keeps the gas flow safe but we do not always understand how that works. On a barbecue the same valve is used but the “pilot” flame is the entire rotisserie burner.
All barbecue grills that have a rotisserie will have similar instructions to tells us to push and hold the knob of the valve. Because the gas flow has to move up and around to the rotisserie burner the instructions will ask is to hold this knob “in” for 10 to 30 seconds. After that the burner will ignite if the gas has made its way around to come through the burner.
Once the burner is burning the instructions will advise up to continue holding the knob “in” for an additional 30 seconds before we allow the knob to release and use the knob to dial the heat high or low.
When a customer contacts us at Grill-Repair.com to complain about a problem with their barbeque rotisserie the problem is almost always that the burner is going out when they release the knob. By holding the knob in the “in” position the gas is flowing but when the knob is released the gas no longer flows. I have seen all kings of contraption people have created to keep the rotisserie knob depressed while they are barbecuing. Recently a client suggested that Alfresco distribute a stainless steel 2×4 because he had been using a block of wood so long he needed to replace the 2×4 he left leaning against the grill to hold the knob “in” while using the rotisserie.
The safety valve — or pilot valve — is used as a safety precaution and using clamps, wood, bricks to hold the knob in so gas will flow is dangerous. Aside from the obvious problem of a block of wood around open flames, aside from the problem of impediments lying around the barbecue to trip us up the original reason for the pilot valve is to turn the gas off if the flames are extinguished for any reason.
When we decide to use the rotisserie the first thing we do is turn on the gas to the barbecue. When we turn on the gas the gas flow stops at the control valves because the control valves are in the Off position. On a normal BBQ valve we simply turn the knob to open the control valve and allow gas through. The safety valve also has a ball valve but the safety valve also has a solenoid that continues to keep gas from flowing even when the ball valve is all the way open. When we hold in the knob we are pushing the solenoid pin to allow gas to flow through the ball valve. Most barbeque grill safety valves incorporate the safety valve and the solenoid into one process. DCS uses a ball valve like the other control valves in the barbecue but instead of the valve connecting the flow of gas to the rotisserie burner the DCS valve connects to a button that allows the cook to push the button and hold the solenoid open for gas to flow.
The solenoid inside the rotisserie valve is always going to be in the closed position so gas cannot flow unless something causes the solenoid to open. When lighting the burner that something is us pushing the knob “in” so gas flows but after 30 seconds from ignition what happens?
Next to the infrared rotisserie burner is the electrode that arcs when lighting the burner. Next to the rotisserie igniter electrode is another piece of metal that sticks out in the flames. This is a thermocouple. A thermocouple is a way of generating a small millivolt charge without using a battery or any conventional means of power. When specific kinds of metals conduct heat against one another a millivolt charge is created. The millivolt charge travels through a wire inside a copper sleeve from the tip in the flames all the way down to the solenoid — whether the solenoid is in the ball valve control or in a button that connects to the control valve the thermocouple ends with a piece of steel like a bolt attached to the copper tubing.
Just like in high school physics electrical charge plus copper plus steel equals an electro-magnet. The threaded bolt that screws into the end of the safety valve magnetizes and pulls the safety valve open. The flames at the rotisserie burner create a charge and the charge creates a magnet and the magnet pulls the valve open so gas can flow. Now we can take our hand off the button, off the valve without the flames going out.
When this does not work there are a few things that may need attention. Initially it is important to check the tip of the thermocouple because carbon deposits generated by burning gas could coat the tip and make it less able to create its millivolt charge. Also check the copper line for kinks and breaks that stop the millivolt from creating a magnet at the steel tip. Finally check the threading that screws into the safety valve. Sometimes it is possible for the heating and cooling to cause expansion and contraction that can slowly unscrew the steel so the magnetic tip is less effective.
If something is damaged or broken and proper maintenance as mentioned above does not help it may be possible to exchange the thermocouple. It is rare the thermocouple is damaged as the thermocouple has no moving parts. Without moving parts there is nothing to get damaged or wear out. However, kinks, bends, dirt and carbon can make the thermocouple less effective. Also the solenoid can get stuck inside the control valve so that a weaker thermocouple cannot pull it free. For these reasons sometimes replacing the thermocouple will repair the rotisserie burner.
If the thermocouple is not the problem the safety valve needs to be exchanged. Like the control valves the safety valve has lubrication in the valve body. Sometimes over-heating while grilling and grease firs cause the valves to over heat and the lubrication becomes fricive. In this case the valve has to be replaced. The safety valve can also slowly become less lubricated or get a little dirt in the body so the solenoid becomes stuck. If a stronger thermocouple or new item can pull the solenoid free the rotisserie will function. However, most of the time the rotisserie burner will not stay lit it is because the safety valve itself needs to be exchanged.
As you will see from the images above each barbecue is different and each valve connects differently. As mentioned the DCS safety valve is a button that connects to the control valve connecting the the gas manifold. The Viking barbeque grill bolts through the manifold and the Solaire safety valve includes the control valve that screws into threading in the manifold.
Always use high quality replacement parts when repairing your barbecue grill and use certified technical assistance.