Gas fireplaces have become a popular choice for home heating and ambiance, offering both practicality and style. One crucial component of these fireplaces is the ignition system, which is responsible for lighting the burner and maintaining efficient operation. Understanding the differences between ignition systems can help you make an informed decision based on your needs.

Two common types of ignition systems are Millivolt and Intermittent Pilot Ignition (IPI). Each system has its unique characteristics, advantages, and drawbacks. This article will provide a comprehensive comparison between Millivolt and IPI systems, focusing on aspects such as power requirements, pilot light operation, control mechanisms, energy usage, efficiency, reliability, maintenance, and costs.

By exploring these differences, you'll gain a clearer understanding of which ignition system best suits your preferences and lifestyle, whether you prioritize energy efficiency, reliability during power outages, or modern control features.

Comparison Chart

Aspect	Millivolt System	IPI (Intermittent Pilot Ignition) System
Power Requirements	Operates solely off the pilot light, and requires no external power.	Requires external power, typically from a standard electrical outlet.
Pilot Light Operation	Must be lit manually (e.g., with a match or piezo sparker). It can be controlled via wall switches or remotes afterward.	Automatically lights the pilot light when there's a call for heat.
Control Mechanism	Relies on a thermocouple, a technology from 1821.	Uses a modern control board to manage gas flow and ignition.
Energy Usage	Constant pilot light, consuming gas continuously.	Intermittent pilot light only uses gas when needed, saving energy.
Efficiency	Less efficient, higher gas consumption due to continuous pilot.	More energy-efficient, and reduces gas usage by only lighting the pilot when needed.
Reliability	Reliable during power outages, doesn't need external electricity.	May require battery backup to function during power outages.
Maintenance	Simple system with fewer electronic parts, longer life expectancy with minimal maintenance.	More complex with electronic components, may require more maintenance over time.
Cost	Lower initial cost but higher long-term gas costs due to continuous pilot light.	Higher initial cost but long-term savings from reduced gas consumption.
CPI Mode (Continuous Pilot Ignition)	Not applicable.	Includes CPI mode, which allows the pilot to stay on for improved draft and reduced condensation.
Pros	Works during power outages without external power; proven, reliable technology.	More energy-efficient, reduces gas consumption, and offers modern controls and flexibility with CPI mode.
Cons	Continuous pilot light increases gas usage, requires manual lighting, and lacks modern control options.	Requires external power unless battery backup is available, higher initial cost, more complex control system.

What is a Millivolt Ignition System?

Pictured: Kingsman 42" OFP42 Millivolt Outdoor Gas Fireplace

In a millivolt system, gas flows into a series of valves in your gas fireplace, but these valves stay closed unless turned on, so gas won't flow when the fireplace is off. The system uses a thermocouple, a safety device that keeps the pilot light burning as long as it's lit. You can turn the main burner on with a wall switch or remote control, which opens a larger valve only when it's set to "on."

One key feature of millivolt systems is the standing pilot light, which stays on even when the fireplace is off. This ensures the main burner can ignite anytime, without needing electricity. However, keeping the pilot light on all the time can add to your gas bill, costing about $0.60 per day or around $75 per season, depending on gas prices.

Pros

Cons

No External Power Required: Millivolt ignition systems use a standing pilot light, meaning they do not need an external power source to operate. This makes them highly reliable, especially during power outages.  Versatile Control Options: These systems are compatible with a range of control devices, from simple on/off wall switches to advanced programmable thermostatic remotes, providing flexibility in how you manage your fireplace.  Remote-Ready: Millivolt systems are ready to pair with remote controls, enhancing convenience and ease of use.  Pilot Light Flexibility: The standing pilot light can be turned off during extended periods of non-use, helping to save fuel and reduce wear on the system. It can easily be reignited when needed.  Common and Familiar Technology: Being the most common ignition type on the market, millivolt systems are well-understood, widely available, and often more affordable than more specialized ignition systems.

Continuous Fuel Consumption: The standing pilot light continuously consumes a small amount of gas, which can lead to higher fuel costs over time, especially if left on for long periods when not in use.  Manual Ignition Required After Being Turned Off: If the pilot light is turned off, it needs to be manually reignited, which can be less convenient than systems with automatic ignition.  Local Code Restrictions: Some local building codes do not permit the use of standing pilot lights due to safety and efficiency concerns, limiting where these systems can be legally installed.  Safety Concerns: Although rare, a standing pilot light can pose a slight risk of gas leaks if the pilot light goes out unexpectedly or if there are issues with the gas supply, requiring regular maintenance and monitoring.  Not as Energy-Efficient: Compared to systems that use electronic ignition, millivolt ignition systems are generally less energy-efficient because the pilot light burns continuously, even when the fireplace is not in use.

Components of the Millivolt system

• Thermopile: Converts heat from the pilot light into a small electrical current (millivolts) to power the gas valve.

• Pilot Light: A small flame that continuously burns, igniting the main burner when the system is activated.

• Gas Valve: Controls the flow of gas to the pilot light and main burner, operated by the millivolt current from the thermopile.

• Thermocouple: Senses whether the pilot light is on, ensuring the gas valve only opens when the pilot is burning.

• Manual Control/Wall Switch: Allows for manual operation to open the gas valve and light the burner.

• Remote Control (Optional): Some millivolt systems can be connected to a remote for easier operation.

What is an IPI (Intermittent Pilot Ignition) System?

Pictured: Majestic Jasper 30 Traditional Direct Vent Propane Gas Fireplace Insert with IPI Ignition System

IPI, or Intermittent Pilot Ignition, is a modern version of the traditional standing pilot light system. It was developed to save gas by only turning on the pilot light when the fireplace is being used. This system uses an electronic control board to manage gas flow and ignite the burners as needed. It also allows for features like remotes, thermostats, and different burner settings, all controlled by the fireplace's internal system.

In an IPI system, all gas valves, including the pilot light valve, stay closed when the fireplace is off. When you turn the fireplace on, like pressing the 'on' button on a remote, the control board starts the process. The pilot light valve opens, a small amount of gas flows, and an electronic igniter lights the pilot. Once the pilot is lit, the main burner valve opens, and the pilot light ignites the main burners.

Pros	Cons
Energy Efficiency: Only uses gas when the fireplace is in use, reducing consumption and costs.  Enhanced Control: Allows for greater control over flame height and intensity, enabling customization of ambiance and heat output.  Improved Safety: Automatically shuts off the gas supply if the pilot light goes out, preventing gas leaks.	Higher Initial Cost: More expensive to purchase and install compared to CPI systems.  Slightly Slower Ignition: Since the pilot light needs to ignite before the main burner, there might be a slight delay in flame production when turning on the fireplace.

Components of the IPI system

• Electronic Control Module: The system’s brain that controls the ignition sequence and burner operation.
• Pilot Assembly with Spark Igniter: Ignites the pilot flame when needed (does not stay lit continuously).
• Flame Sensor: Detects the pilot flame to ensure safe operation and signals the control module that the pilot is lit.
• Gas Valve: Similar to the millivolt system, it controls the flow of gas to the pilot and main burner, but it’s electronically controlled.
• Thermostat or Remote Control: Used to activate the system, either manually or through a programmed temperature setting.
• Battery Backup: Allows the IPI system to operate during power outages.

Key Differences Between Millivolt and IPI

Energy Usage

Millivolt systems operate with a constant pilot light that burns continuously, consuming gas even when the fireplace is not in use. This results in a steady, albeit inefficient, gas consumption. In contrast, IPI (Intermittent Pilot Ignition) systems use a pilot light that only ignites when needed, significantly reducing gas consumption and making them more energy-efficient.

Efficiency

Millivolt systems are generally less energy-efficient due to their constant pilot light. This continuous burning can lead to higher fuel costs over time. On the other hand, IPI systems are designed to be more energy-efficient. By igniting the pilot light only when necessary, IPI systems offer better fuel economy and lower overall energy costs.

Reliability

When it comes to performance during power outages, Millivolt systems have an advantage. They do not rely on electricity to operate, so they continue to function even when the power is out. In contrast, IPI systems depend on electrical power for ignition. This means that without a backup power source, IPI systems will not operate during a power outage.

Maintenance

Millivolt systems may require more frequent maintenance due to the constant operation of the pilot light, which can lead to soot buildup and other issues. Regular cleaning and adjustments are necessary to ensure optimal performance. IPI systems, however, generally have lower maintenance needs since they don’t have a constantly burning pilot light. Maintenance mainly involves checking electronic components periodically.

Cost

The initial cost of Millivolt systems is usually lower because of their simpler design and lack of electronic components. However, over time, the ongoing gas costs due to the constant pilot light can add up. IPI systems might have a higher initial cost due to the complexity of the electronic ignition system, but they often result in lower long-term costs due to their efficient gas usage.

Which System is Right for You?

Situations Where a Millivolt System is Beneficial

• Power Reliability: If you live in an area with frequent power outages or unreliable electricity, a Millivolt system is advantageous. It operates independently of electricity, so it will continue to function even when the power is out.

• Lower Initial Costs: If your primary concern is upfront cost, Millivolt systems are generally less expensive to purchase and install due to their simpler design.

• Simplicity and Reliability: For those who prefer a straightforward system with fewer electronic components and less complexity, Millivolt systems offer a reliable option with fewer potential points of failure.

Situations Where an IPI System is More Practical

• Energy Efficiency: If you are looking for an energy-efficient solution that minimizes gas consumption, an IPI system is a better choice. Its intermittent pilot light design leads to lower fuel usage and can result in significant cost savings over time.

• Lower Long-Term Costs: While IPI systems may have a higher initial cost, their efficiency can lead to lower gas bills and greater long-term savings.

• Modern Features: If you value modern convenience features like remote control or programmable settings, IPI systems often come with these advanced functionalities, enhancing user experience.

Considerations for Regions with Frequent Power Outages

For regions where power outages are common, a Millivolt system is usually the preferred choice. Its ability to function without electricity ensures that you can still use your fireplace when needed. If you prefer an IPI system but face power reliability issues, consider investing in a backup power source, such as a generator or uninterruptible power supply (UPS), to maintain functionality during outages.

Efficiency and Long-Term Savings Considerations

When evaluating efficiency and long-term savings, IPI systems generally outperform Millivolt systems due to their lower gas consumption. The intermittent pilot light of an IPI system ensures that gas is used only when necessary, which can lead to lower monthly bills and more efficient fuel use. Millivolt systems, while simpler, have a constant pilot light that burns continuously, leading to higher gas consumption and potentially higher costs over time.

In summary, if your priority is reliability during power outages and a lower initial investment, a Millivolt system may be the right choice. However, if you seek greater energy efficiency, advanced features, and long-term cost savings, an IPI system is likely more suitable. Consider your specific needs and regional conditions to make the best decision for your situation.

Environmental Impact

Pictured: Monessen 48" Artisan Vent Free See-Through Linear Fireplace with IPI Plus Ignition

Millivolt Systems

IPI Systems

Continuous Gas Usage: Millivolt systems utilize a constantly burning pilot light, which results in continuous gas consumption even when the fireplace is not actively being used. This constant usage contributes to a higher carbon footprint as more gas is burned over time, leading to increased greenhouse gas emissions. Higher Emissions: Due to the ongoing gas consumption, the emissions associated with Millivolt systems are typically higher compared to IPI systems. This can have a more significant impact on the environment, especially in regions where natural gas is the primary energy source. Sustainability Challenges: The constant operation of the pilot light in Millivolt systems means higher energy consumption, which can be less sustainable in the long run. This is particularly relevant if the gas used is non-renewable. Opportunities for Improvement: To mitigate the environmental impact, consider pairing a Millivolt system with renewable energy sources or improving overall home energy efficiency.

Intermittent Gas Usage: IPI systems feature an intermittent pilot light that ignites only when needed, which means gas is consumed only during ignition. This results in lower overall gas usage and a reduced carbon footprint compared to Millivolt systems. Lower Emissions: With reduced gas consumption, IPI systems produce fewer emissions, making them a more environmentally friendly option in terms of greenhouse gas output. Enhanced Sustainability: Due to their efficient use of gas and lower emissions, IPI systems are generally considered more sustainable. They contribute less to greenhouse gas emissions and are better aligned with efforts to reduce overall carbon footprints. Potential for Green Energy Integration: IPI systems can be part of a broader strategy to incorporate green energy solutions. For instance, using renewable energy sources to power the electrical components of an IPI system can further enhance its environmental benefits.

Safety Considerations

Pictured: Kingsman 44" IDV44 Direct Vent Gas Fireplace Insert

Millivolt Systems

IPI Systems

Manual Control: Millivolt systems typically have manual controls that require users to physically operate the pilot light and gas flow. This can be less prone to electronic malfunctions but may require more attention to ensure safe operation. Thermocouple Safety Device: These systems often include a thermocouple, which is a safety device that shuts off the gas supply if the pilot light goes out, preventing gas leaks. Flame Presence Sensor: Some models feature a flame presence sensor that ensures the pilot light is burning correctly. If it detects an issue, it can shut off the gas supply.

Electronic Ignition: IPI systems use electronic ignition to light the pilot flame only when needed, reducing the risk of gas accumulation. This can enhance safety by minimizing the time gas is exposed. Automatic Shutoff: Many IPI systems come with an automatic shutoff feature that stops the gas supply if there is a problem with ignition or if the pilot light is extinguished. Remote and Programmable Controls: These features can enhance safety by allowing users to operate the fireplace from a distance and set specific operating times, reducing the need for manual intervention.

Recommendations for Safe Operation

• Carbon Monoxide Detectors: It is crucial to install carbon monoxide detectors in your home, particularly near sleeping areas and close to the fireplace. These detectors are vital for alerting you to dangerous levels of carbon monoxide, a risk associated with any gas appliance. Regular maintenance of these detectors is essential—test and replace the batteries periodically and ensure they are functioning correctly to maintain effective monitoring.

• Proper Ventilation: Ensuring that your fireplace has adequate ventilation according to the manufacturer’s guidelines is key to preventing the buildup of harmful gases and ensuring efficient operation. Regular inspection of the ventilation system is also important; have it checked periodically to ensure it is free of obstructions and functioning properly.

• Regular Maintenance: Scheduling regular inspections and maintenance for your fireplace system is crucial. A qualified technician can check for leaks, ensure all safety devices are operational, and address any potential issues. Additionally, keeping the area around the fireplace clean and free of flammable materials is important. Follow the manufacturer’s recommendations for regular cleaning of fireplace components to ensure safe and efficient operation.

• User Awareness: To ensure safe operation, familiarize yourself with the operation and safety features of your specific fireplace system by thoroughly reading the user manual. Adhering to all safety and operational guidelines provided by the manufacturer will help maintain the safe use of your fireplace system.

FAQs

What happens if the power goes out with an IPI system?

With an Intermittent Pilot Ignition (IPI) system, the fireplace relies on electrical power to ignite the pilot light and operate the control system. If the power goes out, the fireplace will not function until power is restored. However, many IPI systems come with battery backup options that can keep the system operational during a power outage. It’s important to check your specific model's features or consult with a professional to understand your options for backup power.

How much gas does a Millivolt system use annually?

A Millivolt system, which uses a standing pilot light, tends to use more gas compared to an IPI system because the pilot light burns continuously. On average, a Millivolt system might use around 300-500 therms of gas annually, depending on factors such as the size of the fireplace, how often it’s used, and local gas rates. This can translate to a higher annual gas cost compared to IPI systems, which have a more efficient ignition process.

Can you upgrade from a Millivolt to an IPI system?

Yes, it is possible to upgrade from a Millivolt system to an IPI system, but the process may involve significant changes. You would need to replace the entire control system and possibly the burner assembly, depending on the compatibility with your existing fireplace. It’s advisable to consult with a professional to evaluate the feasibility and cost of such an upgrade, as well as to ensure that the new system is compatible with your fireplace’s structure.

What maintenance is required for a Millivolt system?

A Millivolt system requires regular maintenance to ensure proper operation and safety. This includes checking the pilot light, cleaning the burner and pilot assembly, inspecting the thermocouple, and ensuring the gas lines are secure and free of leaks. Annual servicing by a professional is recommended to keep the system in good working condition.

Can I install an IPI system myself, or should I hire a professional?

While it is technically possible to install an IPI system yourself if you have experience with gas systems and electrical wiring, it is highly recommended to hire a professional. Proper installation is crucial for safety and functionality, as improper installation can lead to gas leaks, electrical issues, or system malfunctions.

How do I know if my gas fireplace is using an IPI or Millivolt system?

You can determine the type of system your gas fireplace uses by checking the user manual or contacting the manufacturer. Another way is to inspect the control panel and ignition system. An IPI system typically has an electronic ignition with a control board, while a Millivolt system features a standing pilot light and a simpler control setup.

Conclusion

Choosing between Millivolt and IPI (Intermittent Pilot Ignition) gas fireplace systems ultimately depends on your specific needs and priorities.

Millivolt systems offer a time-tested, reliable option with the advantage of functioning without external power, making them ideal for areas prone to power outages. Their simplicity and affordability make them a solid choice for those who prefer a straightforward approach, though the continuous pilot light does result in higher long-term gas costs.

On the other hand, IPI systems bring modern efficiency and convenience to the table. Their intermittent pilot light design significantly reduces gas consumption and operating costs over time. With advanced features like remote controls, thermostats, and improved safety mechanisms, IPI systems cater to those who value energy efficiency and modern control options, despite the higher initial investment and dependency on external power.

When deciding which system is best for you, consider factors such as energy efficiency, cost, reliability during power outages, and maintenance requirements. By aligning these considerations with your lifestyle and heating needs, you can make an informed choice that enhances both the functionality and enjoyment of your gas fireplace.

Whether you choose the classic reliability of Millivolt or the modern efficiency of IPI, understanding the differences between these systems will help you optimize your home’s comfort and heating performance.

Where To Buy Gas Fireplaces?

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