What Is a Thermocouple? | Better Plumbing Solutions Melbourne

A thermocouple is a safety device commonly found in older gas hot water systems, gas heaters and gas appliances.

Its job is to detect whether the pilot flame is burning. If the flame goes out, the thermocouple automatically shuts off the gas supply to prevent unburnt gas from escaping, helping keep your home safe.

How Does a Thermocouple Work?

A thermocouple consists of two different metal wires joined together at one end.

When heated by the pilot flame, the thermocouple generates a small electrical current that keeps the gas valve open.

When the Pilot Flame Is On:

✔ Thermocouple is heated
✔ Electrical signal is produced
✔ Gas valve remains open
✔ Hot water system continues operating

When the Pilot Flame Goes Out:

✔ Thermocouple cools down
✔ Electrical signal stops
✔ Gas valve closes automatically
✔ Gas supply is shut off safely

Signs of a Faulty Thermocouple

A failing thermocouple is one of the most common causes of pilot light issues on older gas hot water systems.

Common symptoms include:

• Pilot light won’t stay lit
• Pilot light repeatedly goes out
• No hot water
• Gas burner won’t ignite
• Hot water system keeps shutting down

If the pilot light ignites but goes out as soon as you release the gas control button, a faulty thermocouple is often the cause.

Can a Thermocouple Be Replaced?

Yes. Thermocouples are relatively inexpensive components and can usually be replaced without replacing the entire hot water system.

However, if your hot water service is older and experiencing multiple faults, it may be worth considering a replacement system.

Do Continuous Flow Hot Water Systems Have Thermocouples?

Most modern continuous flow hot water systems do not use a thermocouple.

Instead, they use electronic ignition systems and flame sensors to monitor burner operation.

Thermocouples are most commonly found in older:

• Gas storage hot water systems
• Gas wall furnaces
• Gas space heaters
• Gas appliances with pilot lights

When Should You Call a Plumber?

If your gas hot water system has:

• No hot water
• A pilot light that won’t stay lit
• Intermittent operation
• Ignition issues

it’s best to have it inspected by a licensed plumber or gas fitter.

Better Plumbing Solutions

At Better Plumbing Solutions, we provide:

✔ Gas Hot Water Repairs
✔ Thermocouple Replacement
✔ Gas Hot Water Servicing
✔ Hot Water System Replacement
✔ Continuous Flow Hot Water Upgrades
✔ Licensed Gas Fitting Services

0468 582 686

Servicing Melbourne and surrounding suburbs.