How Electronic Ignition (IPI) Fireplaces Work

In a previous post, we talked about how gas fireplaces work in simple terms, which covers what is called a millivolt gas fireplace system.

To summarize that post, a millivolt system works like this:

A key feature of a standard millivolt system is that the pilot light is always running, even when the fireplace is off. This is called a standing pilot light, and it ensures that whenever you are ready to turn the fireplace on and enjoy some flames, your pilot light can light the main burner. The entire millivolt system requires no external power source, and it all relies on the pilot light running. But if the pilot light is always running, doesn’t that waste gas? Enter the new electronic ignition systems for your gas fireplace.

A standing pilot light that runs 24/7 will cost you an estimated $.60 per day, depending on the gas prices in your area. That’s just under $20 a month, or $75 per season. With the new IPI systems, that cost is almost entirely eliminated.

For a while, it looked like natural gas prices might skyrocket, and so manufacturers put their heads together to come up with a way to ensure that the only time your pilot light is on is when the fireplace is running. To do this, they needed to solve a couple of problems. First, they would need a way to ignite the pilot light and the main burner, without someone having to get up and push a button. In order to do that (in a modern way) they would need to integrate a circuit board or control module to be smart enough to open and close the gas valves on-demand and create a spark. Lastly, to use that circuit board they would need a pretty decent amount of power. Once these problems were solved, the manufactures could add all sorts of extras, such as remotes, thermostats, burner settings and more – all controlled through the ‘computer’ inside your fireplace.

To make it really simple, a modern electronic ignition fireplace that is set to IPI mode goes through the following steps:

So what are the real differences between modern (IPI) and millivolt gas fireplaces?

The real difference is a simple sentence is: A modern gas fireplace has the ability to ignite without the pilot light running, which keeps your gas bill lower throughout the heating season.

Another false claim going around the internet is that modern gas fireplaces do no work in a power outage, but millivolt systems do. This does not have to be true. A battery backup can be purchased for most modern systems that will ensure you can still use your electronic ignition fireplaces in the event of a power outage. The battery simply acts as a power source while the power is out.

Many fireplace manufacturers have included a feature in newer fireplaces that allow them to be set to CPI or continuous pilot ignition mode. The reasons for this are simple and indicative of a problem: Electronic ignitions sometimes fail to work on a start-up sequence. This rarely happens, and it is no fault of the fireplace manufacturers. The reason for this is because of the gas itself. As the gas sits in the line for a long period of time, air can push ahead of it, causing the first couple of attempts to call for heat to not work. This generally happens after a period of long activity. Also, some customers are not concerned with the $75 per season it may cost to run a pilot light continuously. In addition to these reasons, a standing pilot light can keep a draft in your chimney/vent, reduce condensation, and keep snow off any cap you may have where the vent terminates. From one of the Mendota owners manuals:

“Mendota recommends that CPI mode is used during the winter months when the average daily high temperature falls below 50° F. This will keep the fireplace chimney heated for proper updraft during burner ignition, and it will also eliminate excessive condensation of exhaust vapors on the door glass. Leaving the fireplace in CPI mode will keep the fireplace body warm and eliminate cold drafts and heat loss to the cold air that is trapped inside the firebox.”

An IPI gas fireplace does not require the pilot light to run all the time. It uses a control board and an external power source to electronically ignite the burners and operate the gas valves. You don’t have to worry about “what if my pilot light goes out” scenarios. The introduction of a control board into a modern gas fireplace will certainly provide additional options in the future, such as voice-controlled fireplaces.

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