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What Does the Thermocouple Do on My Water Heater?

Without a water heater in your home, the miracle of indoor plumbing (“the best thing since indoor plumbing” is still one of the measuring sticks of progress) will not mean much. You need hot water for many daily activities, so a working water heater is essential.

But you also need a safe working water heater, and that’s where the thermocouple comes in. If you, like many homeowners, use a gas-powered water heater, the thermocouple helps prevent the heater from turning into a danger. But sometimes the thermocouple itself may need repairs and replacement, and for that you’ll need professionals in water heater repair in Doylestown, PA, like those at Carney Plumbing Heating & Cooling. We offer same day service, satisfaction guaranteed, so make us your first call for restoring your malfunctioning water heater.

The job of the thermocouple

The thermocouple is a simple safety component made from two strips of different types of metal, joined at one end. The thermocouple is attached near the pilot light along the burner assembly, with the two ends of the metal placed in the flame of the pilot light, and the other end attached to a shut-off valve for the natural gas line that feeds gas to the burner. Should the pilot light fail, the thermocouple will automatically close off the gas line and prevent the combustion chamber from flooding with unburned gas, creating a major hazard of explosion from even the smallest spark.

The way a thermocouple does this task is through a principle known as the “Seebeck Effect.” The Seebeck Effect describes how two different types of metal in proximity to each other will create an electric current when exposed to heat. The higher the heat, the stronger the current. This makes a thermocouple a crude temperature sensor. As long as electric current runs through the thermocouple because of the heat of the pilot light, the current keeps the valve open. If the pilot fails, so does the current, and the valve automatically closes.

Not all water heaters use a thermocouple. Some of the more recent models use a mercury sensor to shut off the gas valve. An electric water heaters don’t use gas at all, and therefore doesn’t need any kind of emergency gas shut off.

Thermocouples can fail and require replacement. To make sure that your water heater remains safe all year long, have a yearly maintenance visit from a professional to detect any troubles such as failing thermocouples.

The experts at Carney Plumbing Heating & Cooling can help you with maintenance and any water heater repair in Doylestown, PA that you need. Call us today. 

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