What does it cost to fix a water heater pilot light?

The numbers

Fixr's repair guide lists the pilot light in both of its tables:

Fixr's description of the repair: the pilot light is a flame that lights up the burner of the heater, and the pilot might go out for various reasons. The thermocouple may need readjusting, or the light might simply need to be re-lit by a professional.

Note the shape of that: repair can cost more than replacement here, which is unusual. It reflects what the visit involves rather than what the part costs, since a repair may include diagnosis and adjustment work that a straight swap does not.

First, the free option

This Old House puts the unlit pilot at the top of the no-hot-water list and calls it a relatively easy fix. Every gas water heater carries a relighting procedure on a label on its side, and on many units it is a matter of turning the gas control to pilot, holding the button and igniting.

Our advice, marked as ours: read that label before calling anyone. If the pilot lights and stays lit, you have spent nothing, and the $75 to $175 stays in your pocket. Fixr prices the professional version; it does not tell you to try first.

Two situations where you should not try: if you smell gas, and if the pilot has gone out repeatedly. The first is an emergency, the second is a symptom.

When it will not stay lit

A pilot that lights and then dies the moment you release the button is a different fault, and a dearer one. That is the thermocouple at $150 to $325, the safety device that has to sense the flame before gas keeps flowing.

If the pilot stays lit but the burner never fires, you are looking at the gas valve at $150 to $300.

This Old House's list of causes behind a total loss of hot water names the same three parts: a failed thermostat, heating element or gas control valve.

The safety rules around the pilot

This Old House's safety guide is blunt about what a pilot flame is near. Its plumbing expert Richard Trethewey, on a garage installation: had you spilled any of those liquids, the fumes could be drawn right into here, and the gas pilot could cause a fire, thousands of fires every year.

The guide's own rules:

• Elevation. If the water heater is in a garage, ensure it is raised so the pilot light is at least 18 inches above the floor, which helps prevent ignition of gasoline vapours that collect near the floor.
• Clearance. Maintain the clearance around the water heater specified by the manufacturer.
• Remove combustibles. Clear the area of paper, dust and other flammable materials.
• Professional installation. Always hire a licensed professional to install or relocate the unit.

A pilot that keeps going out in a garage is worth checking against the first of those before paying for parts. Relocating a unit has its own price, on the relocation page.

What a repeat failure is telling you

Fixr prices backdraft at $100 to $500 as a separate repair. A pilot that blows out on windy days, or whenever the furnace or an extractor runs, is usually a venting or draught problem rather than a pilot problem, and replacing the pilot assembly will not fix it. See water heater venting cost.