Standing Pilot - Short #228 · HVAC School - For Techs, By Techs summary

Key takeaways

Standing pilot systems are still used in various applications, and understanding them is crucial for HVAC professionals.
Thermocouples and thermopiles are vital components of standing pilot systems, generating the necessary voltage for gas valves to operate safely.
Maintaining clean and secure electrical connections is essential to prevent operational issues in standing pilot systems.
Safety mechanisms in standing pilot systems are critical to avoid dangerous gas buildups.
New training resources are available for those looking to enhance their knowledge about heat pumps and other HVAC technologies.

Summary

Introduction to Standing Pilot Systems

In this episode, Brian introduces the concept of standing pilot gas systems, noting that they are less commonly worked on today but still prevalent in certain applications like fire pits, fuel logs, and water heaters. He shares a personal anecdote that sparked his interest in discussing standing pilot systems after experiencing issues with his own fire pit.

The Mechanics of Standing Pilots

Brian explains how standing pilot systems work, involving thermocouples and thermopiles that generate a small millivolt signal to control the gas valve. He emphasizes the difference between thermocouples, thermopiles, and flame rods, clarifying the implications for maintenance, such as cleaning protocols. He elaborates on the safety mechanisms in these systems that prevent gas buildup, highlighting the importance of maintaining clean connections to ensure proper functioning.

Challenges and Solutions for Standing Pilots

Discussing the challenges that come with standing pilot systems, Brian points out their sensitivity to poor electrical connections due to low voltage operations. He shares troubleshooting tips, including ensuring tight and clean connections and adjusting pilot sizes, using his own experience with his fire pit as a teaching example. The episode underlines the importance of understanding each component's role to maintain safe and efficient operation.

Show notes

In this short podcast episode, Bryan talks about the standing pilot gas systems and the ignition strategy in gas-fired appliances.

Standing pilots are very simple devices that are common in fuel logs, water heaters, and some pool heaters. These devices have a thermocouple or thermopile; in a thermocouple, two dissimilar metals are connected at one end, and there is an electron flow between the metals when one is heated up. A thermopile is a collection of thermocouples in series or parallel to generate more millivolt signals. (Both of these can be damaged if cleaned; don't mistake these for the flame rod! Flame rods can be cleaned with a delicate material.)

To use a standing pilot, turn the dial to the pilot mode and press it in, which allows gas to come through the pilot. Then, you can light the gas (with a lighter or spark mechanism) and keep the dial depressed until there is enough heat generated on top of the thermocouple or thermopile, which allows it to lock in and keep the pilot lit (and pass the entire safety circuit). Then, you turn the gas valve on and let the main burner take over.

If one safety is open, the entire circuit breaks to prevent unspent fuel from accumulating and causing a dangerous condition. One of the main challenges with standing pilots is that they are prone and very sensitive to corrosion due to the low voltage and current. Clean and tight connections can mitigate these risks.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.

Subscribe to our YouTube channel.

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android

Standing Pilot - Short #228