Gas Valve Types and Operation on GAS FURNACES!

Summary

This HVAC training video explores various types of gas valves used in gas furnaces, detailing their evolution for improved safety and efficiency. It covers manual lighting procedures, the workings of combination gas valves, and modern intermittent pilot ignition systems, including smart valves with circuit boards. The video also discusses single-stage, two-stage, and modulating gas valves, emphasizing their functionality in controlling gas flow for heating. Viewers are encouraged to explore additional resources on the AC Service Tech Channel for further learning and troubleshooting.

Takeaways

• 😀 Gas valves in furnaces have evolved for safety and efficiency.
• 😀 A 750 mV gas valve relies on a thermopile to maintain a standing pilot flame.
• 😀 Combination gas valves use a thermocouple for low voltage power to keep the pilot lit.
• 😀 Intermittent pilot ignition gas valves require 24V power to operate and verify flame presence.
• 😀 Smart valves incorporate a circuit board for enhanced control and verification of flame.
• 😀 Direct ignition gas valves allow for gas flow based on 24V power application.
• 😀 Two-stage gas valves manage gas flow for low and high fire stages.
• 😀 Three-stage gas valves add an extra solenoid for more precise gas control.
• 😀 Modulating gas valves communicate with the furnace for improved efficiency.
• 😀 Additional resources for HVAC learning can be found at acer.com.

Q & A

What is the function of a thermopile in a gas valve system?

A thermopile generates low voltage power when heated by a pilot flame, which helps keep the pilot solenoid open in the gas valve.

How does a standing pilot gas valve operate?

In a standing pilot gas valve, the pilot flame is manually lit and maintained by a thermocouple or thermopile that generates power to keep the gas flowing.

What distinguishes an intermittent pilot ignition gas valve from a standing pilot valve?

An intermittent pilot ignition gas valve only lights the pilot when there is a call for heat, using a control to ignite the flame and verify its presence, unlike a standing pilot which is always lit.

What is a smart valve and how does it function?

A smart valve includes a circuit board that manages the ignition process by powering a hot surface igniter, verifying flame presence, and controlling the main gas flow.

What are the typical voltage requirements for modern gas valves?

Most modern gas valves operate on 24 volts for control, with some smart valves requiring additional 120 volts for specific functions.

What is the purpose of a two-stage gas valve?

A two-stage gas valve allows for low and high fire operation, optimizing gas flow for efficiency by adjusting to heating demands.

How do three-stage gas valves differ from two-stage valves?

Three-stage gas valves add an extra solenoid to provide a third stage of gas flow, allowing for more precise control of heating output.

What is the role of the inducer motor in relation to modulating gas valves?

The inducer motor works in conjunction with the modulating gas valve and the furnace circuit board to regulate combustion and improve efficiency.

Why have manufacturers moved towards modulating gas valves?

Manufacturers have shifted to modulating gas valves to increase efficiency by allowing more precise control of gas flow based on heating needs.

Where can additional resources on HVAC and gas valves be found?

Additional resources, including quizzes and articles, can be found on the AC Service Tech Channel website at acer.com.