Red Flags for a Malfunctioning Thermocouple in a Water Heater > 자유게시판

When a hot water faucet drips or the heater just won’t kick on, the culprit is often a defective thermocouple. This small, metal device sits on the flame of the pilot of a gas water heater and keeps the gas valve open only when the pilot is lit. If it fails, your heater can lose heat or even pose a safety hazard. Being aware of the warning signs can help you detect problems before they become costly fixes.

1. Pilot Light Frequently Extinguishes
The most obvious sign is that the pilot flame repeatedly goes out. A healthy thermocouple creates a small electric current when exposed to heat. That current keeps the gas valve open. If the thermocouple is stuck in a "cold" state, the valve will close, and the pilot will extinguish. You may find yourself continuously relighting the flame.

2. Heater Shuts Off While Water Remains Hot
Following the pilot ignition, the heater should stay on, heating water for 20‑30 minutes. If the thermocouple fails, the gas valve will turn off early, even though the water stays hot. You'll see the temperature fall suddenly, and the heater will need relighting every time.

3. Unusual Smells or Lack of Heat
A faulty thermocouple may activate the safety shut‑off, stopping gas flow. This might produce a slight chemical odor 名古屋市東区 給湯器 交換 from the gas or, worse, no heat. If you smell gas or find the water heater’s thermostat reading is far below the set temperature, check the thermocouple.

4. Pilot Light Flickers or Appears Dim
When a thermocouple is marginal, the pilot flame may look weak or flicker. This is because the gas valve is intermittently closing and opening. The pilot may seem steady, but the control is actually unstable.

5. Variable Water Temperature
If the water temperature swings wildly—sometimes hot, sometimes lukewarm—your thermocouple might be drifting out of calibration. A minor misalignment can make the gas valve open at incorrect times.

6. Physical Damage or Corrosion
Look for visible signs of wear on the thermocouple. Corrosion, cracks, or a broken stem means it can no longer generate sufficient voltage. Long-term, the metal may degrade, particularly in damp or humid environments.

7. Pilot Light Delayed Response
If you manually ignite the pilot flame and the thermocouple lags, it could be stuck. A delayed response usually means the sensor isn’t detecting heat correctly.

8. Error Codes and Warning Lights
Contemporary gas water heaters will often show error codes if the thermocouple fails. A flashing LED or a code on the control panel can point to a "pilot light" or "sensor" issue.

9. Unusual Noise from the Heater
If you hear a rattling or clicking sound when the heater starts, it may indicate the gas valve flickers—another sign of a failing thermocouple.

10. Repeated Pilot Relighting by a Plumber
If a plumber has to relight the pilot repeatedly over a short period, it’s a clear indicator that the thermocouple isn’t functioning properly.

Fixing a Bad Thermocouple
Turn off the gas supply and wait for the heater to cool
Remove the old thermocouple using a wrench or pliers
Look for corrosion or damage; if present, replace it
Wipe down the connection points and pilot flame area
Put in the new thermocouple, aligning its stem with the pilot flame
Turn the gas back on, relight the pilot, and ensure the heater stays on

If you’re uncomfortable working with gas appliances, call a licensed plumber
Replacing it promptly can stop gas waste, restore hot water, and keep your home safe