Call a plumber: noise at the water heater

Why this happens

Rheem says that when a temperature and pressure relief valve discharges, it may mean an unsafe temperature or pressure condition, and to contact a licensed plumber immediately. Rheem adds that without that valve the tank may rupture or explode. A. O. Smith says popping from a tank could mean sediment, that the best cure is to flush the tank, and that knocking is likely water slamming into the heater's internal shutoff valves too quickly. It lists hissing and whistling sounds among causes that depend on the heater type.

What to do right now

1. If you smell gas at any time, leave the house and call 911 and your gas utility from outside.
2. The Pennsylvania PUC says not to turn lights on or off or make calls from inside.
3. Atmos Energy says not to rely on your sense of smell alone, and to use sight and hearing too. If hissing comes from near a gas line or the burner area, treat it as a possible gas leak: leave the house and call 911 and your gas utility from outside.
4. If water is coming out of the relief valve pipe, keep people and pets away from the end of that pipe. Rheem warns that hot water drained from a heater can scald.
5. Never cap, plug or block the relief valve or its pipe.
6. If water is flowing steadily from the relief valve pipe or the tank is leaking, and you are confident doing it, turn off the power at the breaker or the gas at the shutoff valve, then close the cold water valve leading to the heater, as A. O. Smith advises, by hand and never forcing it. Only touch the breaker if you are on dry floor and nothing electrical is wet, because Ready.gov says not to touch electrical equipment if it is wet or if you are standing in water. If you cannot do this safely, stay back and call the plumber.
7. Do not open the heater's panels. Leave tank flushing to the plumber; Rheem notes that draining a heater can put you at risk of being scalded.
8. Call a licensed plumber or an authorized water heater service provider. If water has come out of the relief valve pipe, call right away, because Rheem says to contact a licensed plumber immediately.

When to stop. Any gas smell, steady water from the relief valve pipe, or a leak under the tank means stop and call. Gas smell means leave first.

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