How Does A Gas Oven Work

Gas ranges and ovens manufactured today are actually very safe. That's because unlike in the past where most gas ranges and wall ovens used a freestanding pilot light, today's gas ovens rely on an oven safety valve that will not permit gas to flow to the burner unless the igniter is glowing red producing enough heat to ignite the gas when it reaches the igniter. And of course, the oven ignitor will not glow red unless there is electricity available. In the past when you had a power failure you could turn on your oven to heat the kitchen. But with today's modern ranges and ovens that is not possible. Let's look at how a gas oven works.

 

The main components of a gas oven system are the safety valve, the burner assembly, the igniter, and some form of control. The control can either be a thermostat that we all are accustomed to, or an electronic control.

The Burner Assembly

The burner is simply an aluminum tube that has been machined and drilled with precise outlets spread along the length of the tube to allow the flame to burn from one end of the burner, sometimes in the front and down the other side. Most of the time the burner assembly has a bracket attached where the ignitor is mounted. This maintains the proper distance between the ignitor and the burner assembly to ensure proper ignition of the gas. The burner assembly sits under a flame spreader that is a heavy piece of metal (not aluminum) designed to distribute the heat evenly throughout the oven cavity.

The Gas Oven Ignitor

Ignitors used on gas ovens today need to be able to handle very high temperatures. They are made of silicon carbide making them capable of dealing with the intense heat. They are called ignitors but in reality they are electrically in the circuit anytime the burner is burning not just at ignition. Electrically the igniter is in series with the oven safety valve.

The Oven Safety Valve

Oven safety valves used on today's modern gas ranges are designed to prevent gas from flowing to the burner assembly in the event that the igniter is not hot enough to ignite the gas, or if no electricity is present. Inside the oven safety valve is a strip called a bimetal that when not heated forces the gas valve closed. As mentioned before the igniter is electrically in series with the oven safety valve. Electricity flows from the control whether that be a thermostat or an electronic control whenever the oven is requesting a higher temperature. The electricity enters one side of the safety valve passing through the bimetal. When it comes out the other side it passes directly through the oven ignitor. As the oven ignitor heats up its resistance goes down causing the current flow in the circuit to increase. The increase in current flow within the circuit heats the bimetal inside the oven safety valve causing it to flex just enough to allow gas to flow into the burner assembly. Once the gas passes through the burner assembly and comes in contact with the now glowing red hot ignitor it ignites. As long as electricity is flowing through the igniter and the igniter is drawing sufficient current, the bimetal in the oven safety valve will stay flexed open allowing gas to flow.

The amount of current draw within this circuit is determined by the resistance of the igniter. All oven igniters are matched to the oven safety valves by the manufacturer of the oven. It is extremely important that you do not mix and match igniters with different oven safety valves. Always use the model number of the oven or range and select the oven igniter and safety valve recommended by the manufacturer.

And finally, it is possible for an oven ignitor to glow red and still be defective. That's because the resistance of the ignitor is what determines whether or not gas will flow from the oven safety valve. If the resistance of the oven ignitor is only down slightly, it can still glow red but not draw enough current to allow the oven safety valve to open giving the illusion that it is not defective.