Why won't my hot water tank heat up?

Updated February 21, 2017

A hot water tank refers to a heater and storage tank used to supply hot water to a residence or commercial building. Malfunctioning hot water tanks may fail to heat up properly, and require troubleshooting to determine the underlying cause.

Bad Gas Pilot

The pilot light on a hot water tank refers to the small gas flame that provides a source of ignition. The operator can check whether the flame is lit and relight it as necessary. A faulty gas pilot control valve may cause the pilot not to light, and may require replacement to restore proper water heating function.

Bad Thermocouple

Hot water tanks use thermocouples, or electrical devices consisting of two wires joined with a junction, to sense whether the pilot light is hot enough to ignite fuel to the burner. If a thermocouple malfunctions, it may fail to open the gas pilot control valve. Checking the thermocouple for short circuits or other damage in the wires or junction, and performing any necessary repairs or replacements typically corrects the problem.

Bad Thermosat

A thermostat refers to an electrical device that senses temperature and sends signals to the hot water tank to heat the water to a desired temperature. The operator may need to adjust a thermostat set to a low temperature, or replace it if that fails to restore proper hot water tank temperatures.

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