Why Won't My Gas Water Heater Light?

Short answerA. O. Smith points to a gas supply problem, a faulty gas control valve, or a burner clogged by dirt or rust. Blocked air screens can also affect the burner. If you smell gas, leave right away and call from outside. Otherwise, ask a licensed plumber or your gas utility, because these are gas repairs.

What this costs

Our national estimates, not quotes.
Option	Job	Low	High
Replace	Water Heater Replacement	$680	$1,900

Smell first, before anything else

If you notice a rotten-egg, sulfur or garlic smell, or hear hissing, the Public Service Commission of Wisconsin says to leave immediately. Call your gas utility or 911 from a safe distance outdoors. Don't use lights, appliances or cell phones near it, and don't try to light anything.

What might be wrong

Gas supply: is gas reaching the house? If other gas appliances stopped too, call your utility.
Gas control valve: A. O. Smith names this as a possible failure.
Burner: dirt or rust can clog it.
Air screens or filters: A. O. Smith says blocked ones can affect burner performance.
On tankless models: gas supply, venting or the ignition pack.

What you can safely check

Our own checklist, without touching gas parts: are other gas appliances working, is the air screen covered in lint or dust, did your utility send a notice? Beyond that, follow the printed label on your heater and its manual. If you aren't comfortable, call a pro. We don't give steps for lighting or repairing gas equipment.

When to call

A. O. Smith says to call a professional for gas valve, ignition or burner problems beyond basic checks, or any suspected gas leak. A malfunctioning gas appliance can also produce carbon monoxide, according to CPSC. Have it checked before you keep using it, and keep CO alarms working.

No Hot Water in House? What to Check First

Common questions

Why does the pilot keep going out?

A. O. Smith's guide lists supply and control problems, along with burner or air flow issues. We don't give a repair for this. A technician can check them, and you should stop trying if it won't stay lit.

What is a termotanque?

That's a wording note from us, not a source: we see it used in some countries for a tank water heater. In the US, we expect Spanish speakers to say calentador de agua or boiler. The same safety rules apply.