If you have a gas tank water heater and suddenly no hot water, the first thing to check is the pilot light. Sometimes it just went out and relights fine. But if it keeps going out, something is shutting it off. Here's what usually causes it.
Safety First
If you smell gas, which has an added rotten-egg odor, don't try to light anything. Don't flip light switches. Leave the house and call your gas utility or 911 from outside.
Relighting the Pilot
Most gas water heaters have lighting instructions printed on a label on the tank. Follow them exactly. In general, you turn the control to "Pilot," hold the knob down while pressing the igniter button, keep holding for about a minute after the pilot lights, then release and turn the control to "On." Many newer water heaters have electronic ignition and no standing pilot at all.
If the pilot won't light or goes out as soon as you release the knob, don't keep trying over and over. One of the causes below is likely.
Common Causes
A failed thermocouple or thermopile. This small sensor sits in the pilot flame and tells the gas valve the pilot is lit. When it wears out, the valve shuts off the gas as soon as you let go of the knob. It's one of the most common reasons a pilot won't stay lit, and it's a routine repair.
A dirty pilot or burner. Dust, lint and debris can make the pilot flame weak or yellow so it doesn't heat the sensor properly. Garages and laundry rooms are dusty places.
A tripped flammable vapor sensor. Water heaters made in roughly the last 20 years have a sensor that shuts the heater down if it detects flammable vapors, like from gasoline, paint or solvents stored nearby. Once tripped, some models need parts replaced before they'll run again. Keep flammable products away from the water heater.
A venting or air supply problem. If the exhaust can't vent properly or the heater isn't getting enough combustion air, the pilot can go out, and it can be a safety issue. Check that nothing is blocking the vent or crowding the heater.
A gas supply issue. If your gas stove or other appliances also aren't working, the problem may be the gas supply, not the water heater. Contact your gas utility.
A failing gas control valve. If the sensor and pilot are fine, the control valve itself may have failed.
After a Flood
If floodwater reached the burner or gas controls, don't relight the water heater. Have it checked, and in many cases plan to replace it. See plumbing after a hurricane or flood.
Repair or Replace?
A thermocouple, cleaning, or a vapor sensor reset is a repair. If the gas control valve has failed on an older heater, or the tank is near 10 years old and showing rust or leaks, replacement usually makes more sense. See gas vs. electric and tank vs. tankless.
No Hot Water?
Believe Plumbing repairs and replaces gas and electric water heaters across Tampa Bay. See our water heater services or contact us.
Need a Plumber in Tampa Bay?
Believe Plumbing is available 24/7 for emergencies and offers free estimates on all services.