Water heater pilot light won't stay lit? Fixes that work

Having your water heater pilot light repeatedly go out can be a frustrating situation for any homeowner. A functioning pilot is essential for heating water properly and ensuring you have hot water when needed. When the small flame won't stay lit, troubleshooting the root causes and applying fixes is key.

Common reasons a water heater pilot light won't stay lit

There are a few typical culprits behind a pilot light that won't remain ignited on a water heating unit:

• Ventilation problems causing drafts and poor oxygen flow
• Issues with the thermocouple sensor
• Faults in the gas line, valve or control equipment
• Failures or damage in the pilot burner assembly

Drafts and inadequate airflow

For the pilot ignition to sustain a flame, proper ventilation for combustion air is vital. If strong drafts around the water heater are disrupting the pilot, it can repeatedly go out.

An obstructed flue opening or intake that hampers airflow can also prevent the pilot flame from getting enough oxygen. Insufficient ventilation essentially suffocates the fire. Debris, bird nests, or other blockages are often the culprit.

Thermocouple problems

The thermocouple sensor detects the pilot flame. When functioning properly, this signals the gas valve to remain open for heating operation. If the thermocouple malfunctions or loses its reading of the small flame, the gas flow will shut off extinguishing the pilot light.

A bad thermocouple that cannot accurately hold the valve open is a common factor in water heater pilot issues. Over time these thermocouples fail and need replacement to restore proper pilot function.

Gas line or valve defects

To power combustion at the pilot burner, a consistent gas flow is crucial. Leaks, obstructions or damage anywhere along the gas line can disrupt steady fuel delivery causing the pilot flame to go out.

The gas control valve itself could also be malfunctioning and not providing the right gas pressure for pilot ignition. Valve defects often relate to bad thermocouples or general aging issues over time.

Pilot assembly faults

The pilot assembly includes key components that must operate in unison to generate and maintain a flame. This includes the ignition electrode, burner hood, flame sensor, fuel tubing and orifice opening.

Built up debris around the small opening can obstruct smooth gas flow. A damaged electrode wire won't spark properly for ignition. Such pilot assembly problems lead to an unstable flame and cause the pilot light to keep going out.

How to troubleshoot a water heater pilot that keeps going out

When a water heater pilot repeatedly shuts off, methodically checking each potential problem area is crucial for getting to the root cause. Follow these key troubleshooting steps:

Inspect the thermocouple and pilot components

Closely examining the pilot assembly can reveal many issues. Check for any dirt build-up or signs of corrosion around the small opening. Verify the electrode tip is properly oriented with the pilot hood to spark ignition.

Gently twist and move the thermocouple during operation. If the pilot goes out, the thermocouple should be replaced as it likely cannot hold the valve registration due to defects.

Check for ventilation blockages or drafts

Use a flashlight to check the flue and intake openings for any debris, dirt or nesting materials that hamper airflow. Also look for any external chimney damages that could allow drafts across the pilot. Blast compressed air or run a flue brush to clear any clogs if present.

Inspect nearby windows, vents and doors that when opened could be pulling combustion air away and extinguishing the small flame.

Test gas control equipment and supply lines

Use a multimeter to check for consistent voltage to the gas valve. Test for smooth valve opening, closing and consistent pilot gas pressure per appliance specifications.

Inspect supply lines for fitting leaks using gas detector solution, listening for hissing sounds. Fix minor pipe fitting leaks with thread tape. Have professionals address other gas piping issues or full valve replacement needs.

Rule out ignition circuit and switch problems

The ignition modules, wiring, and on/off switch coordinate electrical signals to the pilot and gas valve appropriately. Corroded contacts, shorts or other circuit faults can prevent stable pilot function and flame maintenance.

Professionals can best assess ignition control failures with a voltmeter and test known working replacement parts as needed.

Fixing a faulty thermocouple on a water heater

Since thermocouple failure is a very common reason for water heater pilot issues, replacement fixes this problem point. Take these key steps for DIY thermocouple replacement and pilot testing:

Locate and replace the bad thermocouple

The thermocouple extends from the pilot assembly area back to the gas control valve. After shutting off the appliance, disconnect the thermocouple wiring at the valve. Also detach the tubing fitting at the pilot before unscrewing the thermocouple itself for removal.

Install the new thermocouple, ensuring the tip with sensor bulb at the end seats fully into the pilot hood opening. Tighten fittings securely. Reconnect the lead wires properly at the valve per label codes for the polarity.

Attempt to relight the pilot with replacement part

Turn the water heater back on and initiate lighting steps per the manufacturer details. The new thermocouple should permit the pilot flame to sustain when keeping the reset button depressed for the indicated timeframe.

If the replacement thermocouple still does not hold the valve open appropriately for continuous pilot function, contact a professional for advanced troubleshooting.

Adjust thermocouple position if needed

If properly installed, the new thermocouple itself likely is not faulty. But the positioning of the sensor tip in relation to the pilot flame still requires attention for the right calibration.

Gently bend or twist the apparatus so the bulb end with temperature measurement capabilities sits more engulfed in the flame path. Test for steady pilot continuity when maintaining the reset position engaged.

Clearing obstructions in water heater ventilation

As outlined before, clear and steady appliance ventilation prevents issues with combustion airflow that lead to repeated pilot shut off. DIY clearing steps help resolve this factor when present:

Inspect intake and flue piping

Use a bright flashlight and small mirror at necessary angles to look for any debris or nesting material along intake or flue channels. Look closely for any corrosion holes or separated piping joints allowing cold air leaks across the pilot flame.

Attempt removal of easy debris and obstructions

Use wire hooks or flexible tubing "chimney sweeps" to pull out accumulated leaves, paper nesting items from ventilation channels. Clear webs or cocoons with a stiff wire brush if present.

Blast air puffs down the channels to dislodge and extract debris from openings. Capture removed pieces with tarps to contain the mess.

Assess if professional help needed

If you cannot fully see down channels or easily extract heavy compacted waste, professional flue technicians have industry cameras and vacuum equipment to clear difficult obstructions.

They can also address piping corrosion, separated joints or chimney damage externally that hampers draft ventilation across appliance pilots and burners.

Repairing water heater pilot assembly issues

DIY fixes to certain pilot assembly parts are possible, but gas work dangers require caution. Below are tips targeting common component faults: