Fireplaces and hearth appliances have been evolving rapidly in recent years. That being the case, it is time to get an update on where the industry stands on which pilot light systems are in use and the difference between the various types. Knowing the difference in these systems will give you the knowledge to purchase a fireplace or hearth appliance that meets your exact specifications and the features you need.
Standing Pilot Technology
These types of pilot lights have been the standard in most heating appliances for decades. Many homeowners are familiar with lighting the pilot light in their gas water heater or a gas furnace in their home. A standing pilot is a simple device that maintains a constant, small flame that is both responsible for lighting the main burner in the appliance and for providing the voltage needed for the gas valve to operate. Once lit, the burner can perform its intended duty, be it heating water or air.
A standing pilot assembly is quite simple and is used on many appliances that are fueled by natural gas or propane. A small pilot supply line is connected to the main gas valve in the appliance. When switched to the "pilot" position, gas flows from the gas valve to the pilot assembly, allowing the pilot flame to be lit. Some appliances feature a push button spark ignitor for lighting the pilot light, while others require the pilot to be lit by a match or lighter.
There are a couple of common standing pilot configurations:
Both configurations work on the same principles and adds a small thermal generator next to the pilot flame.
Thermocouples - A thermocouple is a very small thermal generator, which consists of two dissimilar metals fused together at what is known as a cold junction. Focused pilot flames heat the thermocouple and produce the needed voltage for the pilot plunger in the valve to stay open. If the pilot flame goes out for any reason, the pilot plunger will snap closed and gas will cease to flow.
Thermopile - An often accompanying term when speaking of thermocouples, a thermopile is nothing more than a series of thermocouples that are tightly bundled within a larger probe. Gas appliances that require a larger amount of millivoltage to power the gas valve or other peripherals may use these higher output devices. Thermocouples and thermopiles are usually used in conjunction with one another and arranged radially around a central pilot hood. Gas is fed into the central pilot and then diverted toward the adjacent thermocouples and thermopiles. While the power created is higher (up to 750mV for thermopiles), the purpose is generally the same, with the voltage being used to power electromagnets within the valve.
Standing pilot systems are usually low maintenance. There is very little in the way of upkeep needed for these systems, but always reference the appliance's instruction manual on when to have the pilot system serviced, checked, or replaced.
These systems are also very reliable. While wind related issues or dips in gas supply pressure can cause outages, re-lighting a pilot light is very easy on most systems. The best part about standing pilot systems is that they create their own power. They do not need an outlet or another outside power source to work.
While these systems can be reliable, there are some problems that can occur. Common issues can be:
- Pilot outage caused by drafts or air disturbance.
- Insufficient voltage being generated by the thermocouple.
- An internal defect within the gas valve.
- Dust or carbon buildup.
These systems were originally conceived when efficiency wasn't high on the list of priorities for gas appliances being released to market. They constantly use gas to keep the pilot alight, which is less cost effective than an IPI system. These systems are very simple and models with all inclusive controls to allow for flame height or blower control via remote are not as common.
IPI Hearth Controls
IPI stands for intermittent pilot ignition. This system works similar to the previously mentioned standing pilot system but doesn't require a constant flame for the gas valve to operate. The IPI is a smart system that uses an electrode to create the spark the pilot light needs in order for the burners to ignite. When the burner is operating, the pilot remains lit. When the burner shuts down, the pilot will follow suit.
The idea behind the system is actually relatively simple but requires a few more parts than a standing pilot system. An IPI system is electrically wired. When the gas turns on, the system knows to create the spark and ignite the flame using a regulator module that is wired into the fireplace. These systems are usually controlled by a simple wall switch, a remote control, or can be controlled from a smart device if the technology is installed in your fireplace.
These systems are extremely easy to start. A simple flick of a switch or push of a button will ignite it. The convenience of not having to keep up with a standing pilot flame is the biggest upside to this type of system. The IPI system can also be remote controlled using another small module instead of wiring it to a wall switch. The best part is that these can be hooked up to a battery backup system, so the user can make sure their family stays warm during winter power outages.
While the systems do work better than standing pilot systems, they do require more parts to work, which means that more can go wrong with the system. They do require maintenance every 4-5 years, depending on the usage, and will usually need repairs in that amount of time as well. If the fireplace has sat for a few months without being lit, it can be difficult to get the system going again because the gas line may need to be purged, and the pilot system cleaned. These systems are more expensive to buy, install, and repair. They also require a 120 volt power supply or a battery backup system with enough power to light the system.
The Future of Standing Pilots
Advances in technology have given industries the means to make their systems better, including standing pilots. As we push towards every tightening efficiency standards, the Department of Energy (DOE) released strict regulations in 2015 that took direct aim at standing pilot appliances. These regulations tackled safety concerns, efficiency ratings, and overall functional capability that met certain standards. The DOE rules and regulations are far too vast to explain in full detail here and despite the fact that standing pilot hearth appliances were allowed to remain in production for now, efficiency standards will eventually render them obsolete.
Even though the DOE did not succeed in barring the production of standing pilot systems, the proposal to do so was adopted by many municipalities across the country, especially in the western US. Because standing pilot lights are being subjected to more scrutiny than ever before, it is paramount that any consumer interested in purchasing such an appliance check with their local code office before buying to ensure they are accepted.
Electronics were also subjected to the same process and were forced to set a higher standard of efficiency, to which spark ignitor devices and other sub-systems of an appliance now have an energy rating. No one can argue the efficiency standards though, because they do save the homeowner a substantial amount of money, doesn't needlessly waste resources, and ultimately makes the hearth or other appliance safer. As time goes on, and technology increases the industry's ability to create new and innovative products, appliances and electronics of all kinds will receive increased efficiency standards.
IPI systems are becoming much more efficient than they already were. They are faster, more reliable, and have more features included. IPI systems allow the user to have smart technology installed so that they can fully control their fireplace with their smart phone, tablet, or computer over the internet.
When the dust settles, ensuring you have a fireplace that is safe and reliable is all that matters.
The options are there for the user to customize their experience with their hearth. Or, there are appliances that use a standing pilot system that are simpler and reliable.
While newer fireplaces with IPI systems have more advanced technology, some could consider them to be too complicated. For those looking for a simple and reliable system, standing pilot systems continue to be manufactured for now.