Standing Pilot vs. Intermittent Pilot Ignition

Gas fireplace in a white mantel flanked by a millivolt power module on the left and an electronic ignition control box on the right

Key Takeaways

Automatic Safety Shutdown: Both Millivolt and Intermittent Pilot systems mechanically cut gas flow if the pilot or sensor flame is lost, preventing dangerous leaks.
Fuel & Power Efficiency: Millivolt systems run without external power and use minimal fuel, while IPI systems eliminate a standing pilot and include battery backup for outages.
Maintenance & Reliability: Millivolt ignition is simple and widely understood by technicians, whereas IPI offers modern electronic control but may require specialized service.

Gas appliances that are safety-tested rely on switches, sensors, and valves to ignite fires and ensure safe operation if any component fails.

Understanding Gas Ignition Systems in Fireplaces and Outdoor Appliances

Two primary ignition systems used in fireplaces and outdoor gas appliances are Standing Pilot Millivolt Ignition Systems and Intermittent Pilot Ignition Systems. Each system has variations depending on the manufacturer, but the core principles remain consistent.

Standing Pilot Millivolt Ignition Systems

One of the earliest ignition systems used in gas fireplaces, stoves, inserts, and fire pits is the millivolt ignition system. To operate this system, a pilot light must first be ignited either by using a push-button igniter or by manually lighting it with a lighter or match.

How Millivolt Systems Work

The pilot flame heats one or two sensors, creating a small electrical charge. This charge travels via wires to the valve, energizing a magnet that allows gas to flow through the system. Turning on a switch opens the gas to the burner. If the pilot flame goes out, heat is removed, the electric charge dissipates, the magnet de-energizes, and the gas flow stops. This mechanism prevents unwanted gas flow if the flame is extinguished unexpectedly.

Millivolt System Quick Notes

Proven Reliability: Used in fireplaces, furnaces, and hot water heaters for over 50 years, widely familiar to technicians.
Easy Operation: Compatible with on/off switches or remote controls, providing convenient operation.
Enhanced Safety: Automatically shuts down gas flow in the rare event of failure, giving users peace of mind.

Millivolt Gas Valve Image Courtesy Of Kingsman Fireplaces

Intermittent Pilot Ignition (IPI) Systems

Intermittent Pilot Ignition systems, also known as Pilotless, Intellifire, IPI, IP, or Electronic Ignition systems, use electricity—either 120VAC or battery power—to function.

How Intermittent Pilot Systems Work

Upon activation via switch or remote control, an ignition sequence begins. First, the sparker ignites, sending electricity to the pilot gas valve. When spark, fuel, and oxygen combine, the pilot ignites. The pilot flame then heats a sensor, signaling the control module to deactivate the igniter and open the main burner valve, igniting the burner.

Intermittent Pilot System Quick Notes

Fuel Efficiency: Without a standing pilot, gas is used only when the appliance is active.
Battery Backup: Many systems include a battery backup, enabling operation during power outages.
Complexity: Requires an experienced technician for troubleshooting and repairs.
Safety Assurance: The system shuts off gas flow if the pilot sensor doesn't detect a flame, preventing gas leakage.

Intermittent Pilot Valve Image Courtesy Of Kingsman Fireplaces

Conclusion

Whether you choose a Millivolt or Intermittent Pilot ignition system, both offer robust safety features and reliable performance for your gas appliances. Millivolt systems excel in simplicity and long-term familiarity, while Intermittent Pilot systems maximize fuel efficiency and convenience. Evaluate your installation environment, power availability, and maintenance preferences to select the system that best fits your home or business. Always consult a qualified technician for installation and service to ensure optimal safety and operation.

All safety tested gas appliances use a series of switches, sensors, valves etc. to both ignite the fire as well as provide a safety system in case a part fails. There are two common types of ignition systems used in the fireplace and outdoor industries. Standing Pilot Millivolt Ignition systems and Intermittent Pilot Ignition Systems. There are variations of both of these systems from different manufacturers but the information below will lay out how each works and keeps you safe. One of the original types of ignition systems to be used on gas fireplaces, stoves, inserts, and fire pits is the millivolt ignition system. This system requires that a pilot light be lit either with a push button igniter or with a lighter or match. The pilot light heats up one or two sensors. When these sensors are heated, they create a small electrical charge. This electrical charge is sent through a wire or wires back to the valve to energize a magnet. This magnet opens up the pathway for the gas to continue to flow through the valve system. When a switch is turned on, it will open up the gas to the burner. If you remove the pilot light, you remove the heat which removes the electricity, this de-energizes the magnet and shuts the unit off. This prevents the flow of unwanted gas in the case that either the pilot light or burner flame is extinguished. Because of the electrical circuit that is created an on and off switch or a remote control can be used to operate the appliance once the pilot light is lit. Millivolt Quick Notes:

The system has been in circulation with fireplaces, furnace, hot water heaters, for 50+ years. Most installers and technicians are familiar with it. Should anything fail, it is very easy to diagnose.
All appliances using a millivolt gas ignition system can use an on/off switch or a remote control. This allows you to use the appliance with a flip of a switch or from your recliner.
The safety it provides, gives you piece of mind knowing that in the rare occurrence there is a failure that the unit will mechanically shut down.

Millivolt Gas Valve Image Courtesy Of Kingsman Fireplaces

The terms Intermittent Pilot, Pilotless, Intellifire, IPI, IP, and Electronic Ignition are typically all referring to an electronically ignited burner system. This system requires electricity to operate whether in the form of 120VAC power or batteries. Intermittent Pilot Ignition Systems feature a control module/board to carry out the ignition system. Once the switch or remote is used, the ignition sequence begins. First, the sparker will begin to spark and electricity is sent to the pilot side of the valve to energize the electromagnetic device to open up the pilot gas. When you have spark, fuel, and oxygen, the pilot will light. As soon as the pilot is lit, the pilot flame engulfs a sensor which sends a signal back to the units control module to shut off the igniter and send electricity to the burner side of the valve to open it up and allow the pilot light to ignite the main burner flame. Intermittent Pilot Quick Notes:

Without a standing pilot light you are not using fuel when not using the appliance.
Most intermittent pilot systems have a battery back up feature that can operate the system for several months or more. This allows the unit to be used in a power outage.
Because the system is a little more complex, an experienced tech will be need on site should the unit not work properly.
If the pilot sensor does not sense the pilot light, the system will not work and no unwanted gas will pass through the system

Intermittent Pilot Gas Valve Image courtesy of Kingsman Fireplaces.