A gas valve is an electronically controlled device that regulates the flow of natural gas or propane to the furnace burner, controlling flame size and heating output. Modern gas valves integrate safety features including ignition sensing, temperature regulation, and automatic shutoff in abnormal conditions. They operate at pressures of 3.5 to 10 inches of water column, modulating gas flow from 0 to 100 percent.
Types and Functions
Gas valves include solenoid valves that open and close on demand, and modulating valves that adjust gas flow for variable output. High-efficiency and two-stage furnaces use modulating or two-position valves to match heating output to building demand. Gas valves contain pressure regulators, pilot safety shut-off devices, and electronic ignition controls that work together to ensure safe operation.
Maintenance and Replacement
Gas valves typically last 15 to 20 years, though some failure occurs at 10 to 12 years. Common issues include carbon deposits blocking internal passages, solenoid coil failure, and electronic control failures. Replacement costs range from 400 to 800 dollars including labor, representing approximately 30 to 40 percent of furnace replacement cost.