The Brain: Your Gas Control Valve

What It Does

The gas control valve regulates how much gas reaches the burner and when. It monitors the water temperature and responds accordingly:

• Water cools down → valve opens, gas flows, burner fires
• Water reaches temperature → valve closes, burner stops

This cycle happens all day, every day. The valve keeps your water at the temperature you set without overheating it (which would trigger your T&P valve).

The Parts Inside

Several components work together inside the gas control assembly:

The Solenoid — An electrically controlled gate that opens when conditions are safe and slams shut instantly if something’s wrong.

The Main Gas Valve — Controls the volume of gas reaching the burner. Opens gradually when heat is needed, closes when the water’s hot enough.

The Temperature Probe — Extends into the tank and monitors water temperature. This is how the valve knows when to fire up the burner.

The Thermocouple

This one deserves its own section because it’s both a safety device and a power source.

The thermocouple detects whether the pilot flame is burning. If the pilot is lit, it sends a small electrical signal to the solenoid, keeping the gas valve open. If the flame goes out, the signal stops and the valve closes—no unburned gas escaping into your home.

Here’s the clever part: your water heater isn’t plugged in. The thermocouple generates its own electricity using heat from the pilot flame (it’s called the thermoelectric effect). No batteries, no external power. Just physics.

When a water heater won’t stay lit, a failed thermocouple is often the culprit. It’s a relatively cheap part and an easy fix.

The Igniter

How the pilot gets lit depends on your model:

• Standing pilot light — A small flame that burns continuously. You light it manually when needed.
• Electronic ignition — Throws a spark to light the pilot automatically.

Either way, lighting the pilot is straightforward once you know the steps.

When Things Go Wrong

The gas control valve is designed to fail safely. If something’s off, it shuts down rather than creating a dangerous situation.

Common symptoms:

• No hot water
• Pilot light won’t stay lit
• Clicking sounds but no ignition
• Error codes on newer models

These aren’t malfunctions—they’re the system protecting you. But they do mean something needs attention.

Warning Signs

Watch for:

• Inconsistent water temperature
• Pilot that keeps going out
• Strange smells near the heater
• The burner not firing when it should

Gas components aren’t DIY territory. If something seems off, give us a call and let us take a look.