How to Fix the Thermostat on a Hot Water Heater
When you begin to notice that the hot water is not as hot as it should be it may be time to check the hot water heater thermostats. Most water heaters have an upper and lower thermostat. You will need to test the thermostat to find out if either of them is faulty. To fix a hot water heater thermostat will require that you replace the thermostat. Thermostats are available at most hardware stores or plumbing supply houses. Does this Spark an idea?
Things You'll Need
- Phillips-head screwdriver
- Small flat-head screwdriver
- Multimeter
- Hot water heater thermostats
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Instructions
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Turn the circuit breaker off to the water heater. The water heater circuit breaker will be in the home electrical panel box.
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Remove the screws securing the access panel to the thermostat with a Phillips-head screwdriver. You may want to remove both the upper and lower panels at the same time. Pull any insulation that may be covering the thermostat away from the thermostat.
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Turn the upper thermostat to the highest temperature with a small flat-head screwdriver. There is a small screw that controls the temperature settings on the thermostat, which has three terminals above it. The white wire from the thermostat is on the left, the black wire is on the right and there is a terminal screw with no wire directly above the white wire.
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Set the multimeter scale to RX1 and touch one probe to the white wire terminal and the other probe to the terminal above the white wire. You should receive a reading of zero on your meter. Any other reading indicates a faulty thermostat.
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Lower the temperature scale on the upper thermostat by turning the temperature screw to the lowest temperature setting. You may hear a click when you do this. Turn the temperature setting on the lower thermostat to the highest position.
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Place each probe of the multimeter on each of the two terminals on the lower thermostat. The lower thermostat only has two terminals. You should get a reading of zero on the multimeter. If there is any other reading, replace the lower thermostat.
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Loosen the thermostat wire terminals with a Phillips-head screwdriver. Pull the thermostat wires off of the terminal screws. The thermostat secures to the water tank with a steel spring. Slide a flat-head screwdriver between the spring and the thermostat to pry the thermostat up and remove the thermostat from the hot water heater.
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Take the thermostat with you to the hardware store or plumbing supply house. Purchase a thermostat that is the same size and wire configuration. Install the new thermostat between the steel spring and the wall of the hot water tank.
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Place the thermostat wires around the terminal screws and secure the wires by tightening the screws down. Adjust the temperature screw on the thermostat to 120 degrees. Close the access panel doors and secure the doors with the retaining screws. Turn the power back on to the hot water heater.
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Tips & Warnings
Always disconnect power to the hot water heater before attempting repairs.
